Noise characteristics of CT perfusion imaging: how does noise propagate from source images to final perfusion maps?

NASA Astrophysics Data System (ADS)

Li, Ke; Chen, Guang-Hong

2016-03-01

Cerebral CT perfusion (CTP) imaging is playing an important role in the diagnosis and treatment of acute ischemic strokes. Meanwhile, the reliability of CTP-based ischemic lesion detection has been challenged due to the noisy appearance and low signal-to-noise ratio of CTP maps. To reduce noise and improve image quality, a rigorous study on the noise transfer properties of CTP systems is highly desirable to provide the needed scientific guidance. This paper concerns how noise in the CTP source images propagates to the final CTP maps. Both theoretical deviations and subsequent validation experiments demonstrated that, the noise level of background frames plays a dominant role in the noise of the cerebral blood volume (CBV) maps. This is in direct contradiction with the general belief that noise of non-background image frames is of greater importance in CTP imaging. The study found that when radiation doses delivered to the background frames and to all non-background frames are equal, lowest noise variance is achieved in the final CBV maps. This novel equality condition provides a practical means to optimize radiation dose delivery in CTP data acquisition: radiation exposures should be modulated between background frames and non-background frames so that the above equality condition is satisïnAed. For several typical CTP acquisition protocols, numerical simulations and in vivo canine experiment demonstrated that noise of CBV can be effectively reduced using the proposed exposure modulation method.

Background noise cancellation for improved acoustic detection of manatee vocalizations

NASA Astrophysics Data System (ADS)

Yan, Zheng; Niezrecki, Christopher; Beusse, Diedrich O.

2005-06-01

The West Indian manatee (Trichechus manatus latirostris) has become endangered partly because of an increase in the number of collisions with boats. A device to alert boaters of the presence of manatees, so that a collision can be avoided, is desired. A practical implementation of the technology is dependent on the hydrophone spacing and range of detection. These parameters are primarily dependent on the manatee vocalization strength, the decay of the signal's strength with distance, and the background noise levels. An efficient method to extend the detection range by using background noise cancellation is proposed in this paper. An adaptive line enhancer (ALE) that can detect and track narrow band signals buried in broadband noise is implemented to cancel the background noise. The results indicate that the ALE algorithm can efficiently extract the manatee calls from the background noise. The improved signal-to-noise ratio of the signal can be used to extend the range of detection of manatee vocalizations and reduce the false alarm and missing detection rate in their natural habitat. .

Background noise cancellation for improved acoustic detection of manatee vocalizations

NASA Astrophysics Data System (ADS)

Yan, Zheng; Niezrecki, Christopher; Beusse, Diedrich O.

2005-04-01

The West Indian manatee (Trichechus manatus latirostris) has become endangered partly because of an increase in the number of collisions with boats. A device to alert boaters of the presence of manatees, so that a collision can be avoided, is desired. Practical implementation of the technology is dependent on the hydrophone spacing and range of detection. These parameters are primarily dependent on the manatee vocalization strength, the decay of the signal strength with distance, and the background noise levels. An efficient method to extend the detection range by using background noise cancellation is proposed in this paper. An adaptive line enhancer (ALE) that can detect and track narrowband signals buried in broadband noise is implemented to cancel the background noise. The results indicate that the ALE algorithm can efficiently extract the manatee calls from the background noise. The improved signal-to-noise ratio of the signal can be used to extend the range of detection of manatee vocalizations and reduce the false alarm and missing detection rate in their natural habitat.

Magnified Neural Envelope Coding Predicts Deficits in Speech Perception in Noise.

PubMed

Millman, Rebecca E; Mattys, Sven L; Gouws, André D; Prendergast, Garreth

2017-08-09

Verbal communication in noisy backgrounds is challenging. Understanding speech in background noise that fluctuates in intensity over time is particularly difficult for hearing-impaired listeners with a sensorineural hearing loss (SNHL). The reduction in fast-acting cochlear compression associated with SNHL exaggerates the perceived fluctuations in intensity in amplitude-modulated sounds. SNHL-induced changes in the coding of amplitude-modulated sounds may have a detrimental effect on the ability of SNHL listeners to understand speech in the presence of modulated background noise. To date, direct evidence for a link between magnified envelope coding and deficits in speech identification in modulated noise has been absent. Here, magnetoencephalography was used to quantify the effects of SNHL on phase locking to the temporal envelope of modulated noise (envelope coding) in human auditory cortex. Our results show that SNHL enhances the amplitude of envelope coding in posteromedial auditory cortex, whereas it enhances the fidelity of envelope coding in posteromedial and posterolateral auditory cortex. This dissociation was more evident in the right hemisphere, demonstrating functional lateralization in enhanced envelope coding in SNHL listeners. However, enhanced envelope coding was not perceptually beneficial. Our results also show that both hearing thresholds and, to a lesser extent, magnified cortical envelope coding in left posteromedial auditory cortex predict speech identification in modulated background noise. We propose a framework in which magnified envelope coding in posteromedial auditory cortex disrupts the segregation of speech from background noise, leading to deficits in speech perception in modulated background noise. SIGNIFICANCE STATEMENT People with hearing loss struggle to follow conversations in noisy environments. Background noise that fluctuates in intensity over time poses a particular challenge. Using magnetoencephalography, we demonstrate anatomically distinct cortical representations of modulated noise in normal-hearing and hearing-impaired listeners. This work provides the first link among hearing thresholds, the amplitude of cortical representations of modulated sounds, and the ability to understand speech in modulated background noise. In light of previous work, we propose that magnified cortical representations of modulated sounds disrupt the separation of speech from modulated background noise in auditory cortex. Copyright © 2017 Millman et al.

Noise correlations in cosmic microwave background experiments

NASA Technical Reports Server (NTRS)

Dodelson, Scott; Kosowsky, Arthur; Myers, Steven T.

1995-01-01

Many analysis of microwave background experiments neglect the correlation of noise in different frequency of polarization channels. We show that these correlations, should they be present, can lead to serve misinterpretation of an experiment. In particular, correlated noise arising from either electronics or atmosphere may mimic a cosmic signal. We quantify how the likelihood function for a given experiment varies with noise correlation, using both simple analytic models and actual data. For a typical microwave background anisotropy experiment, noise correlations at the level of 1% of the overall noise can seriously reduce the significance of a given detection.

Background noise model development for seismic stations of KMA

NASA Astrophysics Data System (ADS)

Jeon, Youngsoo

2010-05-01

The background noise recorded at seismometer is exist at any seismic signal due to the natural phenomena of the medium which the signal passed through. Reducing the seismic noise is very important to improve the data quality in seismic studies. But, the most important aspect of reducing seismic noise is to find the appropriate place before installing the seismometer. For this reason, NIMR(National Institution of Meteorological Researches) starts to develop a model of standard background noise for the broadband seismic stations of the KMA(Korea Meteorological Administration) using a continuous data set obtained from 13 broadband stations during the period of 2007 and 2008. We also developed the model using short period seismic data from 10 stations at the year of 2009. The method of Mcmara and Buland(2004) is applied to analyse background noise of Korean Peninsula. The fact that borehole seismometer records show low noise level at frequency range greater than 1 Hz compared with that of records at the surface indicate that the cultural noise of inland Korean Peninsula should be considered to process the seismic data set. Reducing Double Frequency peak also should be regarded because the Korean Peninsula surrounded by the seas from eastern, western and southern part. The development of KMA background model shows that the Peterson model(1993) is not applicable to fit the background noise signal generated from Korean Peninsula.

Memory performance on the Auditory Inference Span Test is independent of background noise type for young adults with normal hearing at high speech intelligibility

PubMed Central

Rönnberg, Niklas; Rudner, Mary; Lunner, Thomas; Stenfelt, Stefan

2014-01-01

Listening in noise is often perceived to be effortful. This is partly because cognitive resources are engaged in separating the target signal from background noise, leaving fewer resources for storage and processing of the content of the message in working memory. The Auditory Inference Span Test (AIST) is designed to assess listening effort by measuring the ability to maintain and process heard information. The aim of this study was to use AIST to investigate the effect of background noise types and signal-to-noise ratio (SNR) on listening effort, as a function of working memory capacity (WMC) and updating ability (UA). The AIST was administered in three types of background noise: steady-state speech-shaped noise, amplitude modulated speech-shaped noise, and unintelligible speech. Three SNRs targeting 90% speech intelligibility or better were used in each of the three noise types, giving nine different conditions. The reading span test assessed WMC, while UA was assessed with the letter memory test. Twenty young adults with normal hearing participated in the study. Results showed that AIST performance was not influenced by noise type at the same intelligibility level, but became worse with worse SNR when background noise was speech-like. Performance on AIST also decreased with increasing memory load level. Correlations between AIST performance and the cognitive measurements suggested that WMC is of more importance for listening when SNRs are worse, while UA is of more importance for listening in easier SNRs. The results indicated that in young adults with normal hearing, the effort involved in listening in noise at high intelligibility levels is independent of the noise type. However, when noise is speech-like and intelligibility decreases, listening effort increases, probably due to extra demands on cognitive resources added by the informational masking created by the speech fragments and vocal sounds in the background noise. PMID:25566159

Memory performance on the Auditory Inference Span Test is independent of background noise type for young adults with normal hearing at high speech intelligibility.

PubMed

Rönnberg, Niklas; Rudner, Mary; Lunner, Thomas; Stenfelt, Stefan

2014-01-01

Listening in noise is often perceived to be effortful. This is partly because cognitive resources are engaged in separating the target signal from background noise, leaving fewer resources for storage and processing of the content of the message in working memory. The Auditory Inference Span Test (AIST) is designed to assess listening effort by measuring the ability to maintain and process heard information. The aim of this study was to use AIST to investigate the effect of background noise types and signal-to-noise ratio (SNR) on listening effort, as a function of working memory capacity (WMC) and updating ability (UA). The AIST was administered in three types of background noise: steady-state speech-shaped noise, amplitude modulated speech-shaped noise, and unintelligible speech. Three SNRs targeting 90% speech intelligibility or better were used in each of the three noise types, giving nine different conditions. The reading span test assessed WMC, while UA was assessed with the letter memory test. Twenty young adults with normal hearing participated in the study. Results showed that AIST performance was not influenced by noise type at the same intelligibility level, but became worse with worse SNR when background noise was speech-like. Performance on AIST also decreased with increasing memory load level. Correlations between AIST performance and the cognitive measurements suggested that WMC is of more importance for listening when SNRs are worse, while UA is of more importance for listening in easier SNRs. The results indicated that in young adults with normal hearing, the effort involved in listening in noise at high intelligibility levels is independent of the noise type. However, when noise is speech-like and intelligibility decreases, listening effort increases, probably due to extra demands on cognitive resources added by the informational masking created by the speech fragments and vocal sounds in the background noise.

Effect of background noise on neuronal coding of interaural level difference cues in rat inferior colliculus

PubMed Central

Mokri, Yasamin; Worland, Kate; Ford, Mark; Rajan, Ramesh

2015-01-01

Humans can accurately localize sounds even in unfavourable signal-to-noise conditions. To investigate the neural mechanisms underlying this, we studied the effect of background wide-band noise on neural sensitivity to variations in interaural level difference (ILD), the predominant cue for sound localization in azimuth for high-frequency sounds, at the characteristic frequency of cells in rat inferior colliculus (IC). Binaural noise at high levels generally resulted in suppression of responses (55.8%), but at lower levels resulted in enhancement (34.8%) as well as suppression (30.3%). When recording conditions permitted, we then examined if any binaural noise effects were related to selective noise effects at each of the two ears, which we interpreted in light of well-known differences in input type (excitation and inhibition) from each ear shaping particular forms of ILD sensitivity in the IC. At high signal-to-noise ratios (SNR), in most ILD functions (41%), the effect of background noise appeared to be due to effects on inputs from both ears, while for a large percentage (35.8%) appeared to be accounted for by effects on excitatory input. However, as SNR decreased, change in excitation became the dominant contributor to the change due to binaural background noise (63.6%). These novel findings shed light on the IC neural mechanisms for sound localization in the presence of continuous background noise. They also suggest that some effects of background noise on encoding of sound location reported to be emergent in upstream auditory areas can also be observed at the level of the midbrain. PMID:25865218

ONTOGENY OF THE ACOUSTIC STARTLE RESPONSE AND SENSITIZATION TO BACKGROUND NOISE IN THE RAT (JOURNAL VERSION)

EPA Science Inventory

The purpose of the study was to characterize the ontogeny of the acoustic startle response (ASR), and response sensitization to background noise, in preweanling rats. With constant low-level (45 dB) background noise, response latency decreased steadily with age, whereas, both res...

Sources of interference in item and associative recognition memory.

PubMed

Osth, Adam F; Dennis, Simon

2015-04-01

A powerful theoretical framework for exploring recognition memory is the global matching framework, in which a cue's memory strength reflects the similarity of the retrieval cues being matched against the contents of memory simultaneously. Contributions at retrieval can be categorized as matches and mismatches to the item and context cues, including the self match (match on item and context), item noise (match on context, mismatch on item), context noise (match on item, mismatch on context), and background noise (mismatch on item and context). We present a model that directly parameterizes the matches and mismatches to the item and context cues, which enables estimation of the magnitude of each interference contribution (item noise, context noise, and background noise). The model was fit within a hierarchical Bayesian framework to 10 recognition memory datasets that use manipulations of strength, list length, list strength, word frequency, study-test delay, and stimulus class in item and associative recognition. Estimates of the model parameters revealed at most a small contribution of item noise that varies by stimulus class, with virtually no item noise for single words and scenes. Despite the unpopularity of background noise in recognition memory models, background noise estimates dominated at retrieval across nearly all stimulus classes with the exception of high frequency words, which exhibited equivalent levels of context noise and background noise. These parameter estimates suggest that the majority of interference in recognition memory stems from experiences acquired before the learning episode. (c) 2015 APA, all rights reserved).

Current Background Noise Sources and Levels in the NASA Ames 40- by 80-Foot Wind Tunnel: A Status Report

NASA Technical Reports Server (NTRS)

Allen, Christopher S.; Jaeger, Stephen; Soderman, Paul; Koga, Dennis (Technical Monitor)

1999-01-01

Background noise measurements were made of the acoustic environment in the National Full-Scale Aerodynamics Complex 40- by 80-Foot Wind Tunnel (40x80) at NASA Ames Research Center. The measurements were acquired subsequent to the 40x80 Aeroacoustic Modernization Project, which was undertaken to improve the anechoic characteristics of the 40x80's closed test section as well as reduce the levels of background noise in the facility. The resulting 40x80 anechoic environment was described by Soderman et. al., and the current paper describes the resulting 40x80 background noise, discusses the sources of the noise, and draws comparisons to previous 40x80 background noise levels measurements. At low wind speeds or low frequencies, the 40x80 background noise is dominated by the fan drive system. To obtain the lowest fan drive noise for a given tunnel condition, it is possible in the 40x80 to reduce the fans' rotational speed and adjust the fans' blade pitch, as described by Schmidtz et. al. This idea is not new, but has now been operationally implemented with modifications for increased power at low rotational speeds. At low to mid-frequencies and at higher wind speeds, the dominant noise mechanism was thought to be caused by the surface interface of the previous test section floor acoustic lining. In order to reduce this noise mechanism, the new test section floor lining was designed to resist the pumping of flow in and out of the space between the grating slats required to support heavy equipment. In addition, the lining/flow interface over the entire test section was designed to be smoother and quieter than the previous design. At high wind speeds or high frequencies, the dominant source of background noise in the 40x80 is believed to be caused by the response of the in-flow microphone probes (required by the nature of the closed test section) to the fluctuations in the freestream flow. The resulting background noise levels are also different for probes of various diameters and types. The inflow microphone support strut is also a source of background noise but this source's impact may be minimized by careful design of the strut. In the present paper, the mechanisms mentioned above are discussed in detail. Their frequency and velocity ranges of dominance are defined and the differences between past and current facility background noise levels are presented. This paper gives valuable information for those wishing to make acoustic measurements in the 40x80. With this report and an estimate of the noise levels produced by the noise source of interest, it should be possible to determine the signal-to-noise ratios and measurement locations to successfully perform aeroacoustic testing in the NASA Ames Research Center's 40- by 80-Foot Wind Tunnel.

Difficulty understanding speech in noise by the hearing impaired: underlying causes and technological solutions.

PubMed

Healy, Eric W; Yoho, Sarah E

2016-08-01

A primary complaint of hearing-impaired individuals involves poor speech understanding when background noise is present. Hearing aids and cochlear implants often allow good speech understanding in quiet backgrounds. But hearing-impaired individuals are highly noise intolerant, and existing devices are not very effective at combating background noise. As a result, speech understanding in noise is often quite poor. In accord with the significance of the problem, considerable effort has been expended toward understanding and remedying this issue. Fortunately, our understanding of the underlying issues is reasonably good. In sharp contrast, effective solutions have remained elusive. One solution that seems promising involves a single-microphone machine-learning algorithm to extract speech from background noise. Data from our group indicate that the algorithm is capable of producing vast increases in speech understanding by hearing-impaired individuals. This paper will first provide an overview of the speech-in-noise problem and outline why hearing-impaired individuals are so noise intolerant. An overview of our approach to solving this problem will follow.

Noise Reduction with Microphone Arrays for Speaker Identification

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cohen, Z

Reducing acoustic noise in audio recordings is an ongoing problem that plagues many applications. This noise is hard to reduce because of interfering sources and non-stationary behavior of the overall background noise. Many single channel noise reduction algorithms exist but are limited in that the more the noise is reduced; the more the signal of interest is distorted due to the fact that the signal and noise overlap in frequency. Specifically acoustic background noise causes problems in the area of speaker identification. Recording a speaker in the presence of acoustic noise ultimately limits the performance and confidence of speaker identificationmore » algorithms. In situations where it is impossible to control the environment where the speech sample is taken, noise reduction filtering algorithms need to be developed to clean the recorded speech of background noise. Because single channel noise reduction algorithms would distort the speech signal, the overall challenge of this project was to see if spatial information provided by microphone arrays could be exploited to aid in speaker identification. The goals are: (1) Test the feasibility of using microphone arrays to reduce background noise in speech recordings; (2) Characterize and compare different multichannel noise reduction algorithms; (3) Provide recommendations for using these multichannel algorithms; and (4) Ultimately answer the question - Can the use of microphone arrays aid in speaker identification?« less

Background noise analysis in urban airport surroundings of Brazilian cities, Congonhas Airport, São Paulo

PubMed Central

Scatolini, Fabio; Alves, Cláudio Jorge Pinto

2016-01-01

ABSTRACT OBJECTIVE To perform a quantitative analysis of the background noise at Congonhas Airport surroundings based on large sampling and measurements with no interruption. METHODS Measuring sites were chosen from 62 and 72 DNL (day-night-level) noise contours, in urban sites compatible with residential use. Fifteen sites were monitored for at least 168 hours without interruption or seven consecutive days. Data compilation was based on cross-reference between noise measurements and air traffic control records, and results were validated by airport meteorological reports. Preliminary diagnoses were established using the standard NBR-13368. Background noise values were calculated based on the Sound Exposure Level (SEL). Statistic parameters were calculated in one-hour intervals. RESULTS Only four of the fifteen sites assessed presented aircraft operations as a clear cause for the noise annoyance. Even so, it is possible to detect background noise levels above regulation limits during periods of low airport activity or when it closes at night. CONCLUSIONS All the sites monitored showed background noise levels above regulation limits between 7:00 and 21:00. In the intervals between 6:00-6:59 and 21:00-22:59 the noise data, when analyzed with the current airport operational characteristics, still allow the development of additional mitigating measures. PMID:28099658

Advantages of binaural amplification to acceptable noise level of directional hearing aid users.

PubMed

Kim, Ja-Hee; Lee, Jae Hee; Lee, Ho-Ki

2014-06-01

The goal of the present study was to examine whether Acceptable Noise Levels (ANLs) would be lower (greater acceptance of noise) in binaural listening than in monaural listening condition and also whether meaningfulness of background speech noise would affect ANLs for directional microphone hearing aid users. In addition, any relationships between the individual binaural benefits on ANLs and the individuals' demographic information were investigated. Fourteen hearing aid users (mean age, 64 years) participated for experimental testing. For the ANL calculation, listeners' most comfortable listening levels and background noise level were measured. Using Korean ANL material, ANLs of all participants were evaluated under monaural and binaural amplification with a counterbalanced order. The ANLs were also compared across five types of competing speech noises, consisting of 1- through 8-talker background speech maskers. Seven young normal-hearing listeners (mean age, 27 years) participated for the same measurements as a pilot testing. The results demonstrated that directional hearing aid users accepted more noise (lower ANLs) with binaural amplification than with monaural amplification, regardless of the type of competing speech. When the background speech noise became more meaningful, hearing-impaired listeners accepted less amount of noise (higher ANLs), revealing that ANL is dependent on the intelligibility of the competing speech. The individuals' binaural advantages in ANLs were significantly greater for the listeners with longer experience of hearing aids, yet not related to their age or hearing thresholds. Binaural directional microphone processing allowed hearing aid users to accept a greater amount of background noise, which may in turn improve listeners' hearing aid success. Informational masking substantially influenced background noise acceptance. Given a significant association between ANLs and duration of hearing aid usage, ANL measurement can be useful for clinical counseling of binaural hearing aid candidates or unsuccessful users.

The impact of musicianship on the cortical mechanisms related to separating speech from background noise.

PubMed

Zendel, Benjamin Rich; Tremblay, Charles-David; Belleville, Sylvie; Peretz, Isabelle

2015-05-01

Musicians have enhanced auditory processing abilities. In some studies, these abilities are paralleled by an improved understanding of speech in noisy environments, partially due to more robust encoding of speech signals in noise at the level of the brainstem. Little is known about the impact of musicianship on attention-dependent cortical activity related to lexical access during a speech-in-noise task. To address this issue, we presented musicians and nonmusicians with single words mixed with three levels of background noise, across two conditions, while monitoring electrical brain activity. In the active condition, listeners repeated the words aloud, and in the passive condition, they ignored the words and watched a silent film. When background noise was most intense, musicians repeated more words correctly compared with nonmusicians. Auditory evoked responses were attenuated and delayed with the addition of background noise. In musicians, P1 amplitude was marginally enhanced during active listening and was related to task performance in the most difficult listening condition. By comparing ERPs from the active and passive conditions, we isolated an N400 related to lexical access. The amplitude of the N400 was not influenced by the level of background noise in musicians, whereas N400 amplitude increased with the level of background noise in nonmusicians. In nonmusicians, the increase in N400 amplitude was related to a reduction in task performance. In musicians only, there was a rightward shift of the sources contributing to the N400 as the level of background noise increased. This pattern of results supports the hypothesis that encoding of speech in noise is more robust in musicians and suggests that this facilitates lexical access. Moreover, the shift in sources suggests that musicians, to a greater extent than nonmusicians, may increasingly rely on acoustic cues to understand speech in noise.

[Detection of Weak Speech Signals from Strong Noise Background Based on Adaptive Stochastic Resonance].

PubMed

Lu, Huanhuan; Wang, Fuzhong; Zhang, Huichun

2016-04-01

Traditional speech detection methods regard the noise as a jamming signal to filter,but under the strong noise background,these methods lost part of the original speech signal while eliminating noise.Stochastic resonance can use noise energy to amplify the weak signal and suppress the noise.According to stochastic resonance theory,a new method based on adaptive stochastic resonance to extract weak speech signals is proposed.This method,combined with twice sampling,realizes the detection of weak speech signals from strong noise.The parameters of the systema,b are adjusted adaptively by evaluating the signal-to-noise ratio of the output signal,and then the weak speech signal is optimally detected.Experimental simulation analysis showed that under the background of strong noise,the output signal-to-noise ratio increased from the initial value-7dB to about 0.86 dB,with the gain of signalto-noise ratio is 7.86 dB.This method obviously raises the signal-to-noise ratio of the output speech signals,which gives a new idea to detect the weak speech signals in strong noise environment.

Background Noise Acceptance and Personality Factors Involved in Library Environment Choices by College Students

ERIC Educational Resources Information Center

Gordon-Hickey, Susan; Lemley, Trey

2012-01-01

For decades, academic libraries made efforts to provide study environments differing in acoustic environment. The present study aimed to provide an evidence basis for this practice by comparing background noise acceptance and personality factors of two groups of college-aged students self identified as preferring quiet or background noise when…

The Effect of Background Noise on the Word Activation Process in Nonnative Spoken-Word Recognition

ERIC Educational Resources Information Center

Scharenborg, Odette; Coumans, Juul M. J.; van Hout, Roeland

2018-01-01

This article investigates 2 questions: (1) does the presence of background noise lead to a differential increase in the number of simultaneously activated candidate words in native and nonnative listening? And (2) do individual differences in listeners' cognitive and linguistic abilities explain the differential effect of background noise on…

Cluster signal-to-noise analysis for evaluation of the information content in an image.

PubMed

Weerawanich, Warangkana; Shimizu, Mayumi; Takeshita, Yohei; Okamura, Kazutoshi; Yoshida, Shoko; Yoshiura, Kazunori

2018-01-01

(1) To develop an observer-free method of analysing image quality related to the observer performance in the detection task and (2) to analyse observer behaviour patterns in the detection of small mass changes in cone-beam CT images. 13 observers detected holes in a Teflon phantom in cone-beam CT images. Using the same images, we developed a new method, cluster signal-to-noise analysis, to detect the holes by applying various cut-off values using ImageJ and reconstructing cluster signal-to-noise curves. We then evaluated the correlation between cluster signal-to-noise analysis and the observer performance test. We measured the background noise in each image to evaluate the relationship with false positive rates (FPRs) of the observers. Correlations between mean FPRs and intra- and interobserver variations were also evaluated. Moreover, we calculated true positive rates (TPRs) and accuracies from background noise and evaluated their correlations with TPRs from observers. Cluster signal-to-noise curves were derived in cluster signal-to-noise analysis. They yield the detection of signals (true holes) related to noise (false holes). This method correlated highly with the observer performance test (R 2 = 0.9296). In noisy images, increasing background noise resulted in higher FPRs and larger intra- and interobserver variations. TPRs and accuracies calculated from background noise had high correlation with actual TPRs from observers; R 2 was 0.9244 and 0.9338, respectively. Cluster signal-to-noise analysis can simulate the detection performance of observers and thus replace the observer performance test in the evaluation of image quality. Erroneous decision-making increased with increasing background noise.

Removing Background Noise with Phased Array Signal Processing

NASA Technical Reports Server (NTRS)

Podboy, Gary; Stephens, David

2015-01-01

Preliminary results are presented from a test conducted to determine how well microphone phased array processing software could pull an acoustic signal out of background noise. The array consisted of 24 microphones in an aerodynamic fairing designed to be mounted in-flow. The processing was conducted using Functional Beam forming software developed by Optinav combined with cross spectral matrix subtraction. The test was conducted in the free-jet of the Nozzle Acoustic Test Rig at NASA GRC. The background noise was produced by the interaction of the free-jet flow with the solid surfaces in the flow. The acoustic signals were produced by acoustic drivers. The results show that the phased array processing was able to pull the acoustic signal out of the background noise provided the signal was no more than 20 dB below the background noise level measured using a conventional single microphone equipped with an aerodynamic forebody.

Effects of road traffic background noise on judgments of individual airplane noises. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Powell, C. A.

1979-01-01

Two laboratory experiments were conducted to investigate the effects of road-traffic background noise on judgments of individual airplane flyover noises. In the first experiment, 27 subjects judged a set of 16 airplane flyover noises in the presence of traffic-noise sessions of 30-min duration consisting of the combinations of 3 traffic-noise types and 3 noise levels. In the second experiment, 24 subjects judged the same airplane flyover noises in the presence of traffic-noise sessions of 10-min duration consisting of the combinations of 2 traffic-noise types and 4 noise levels. In both experiments the airplane noises were judged less annoying in the presence of high traffic-noise levels than in the presence of low traffic-noise levels.

The equivalent internal orientation and position noise for contour integration.

PubMed

Baldwin, Alex S; Fu, Minnie; Farivar, Reza; Hess, Robert F

2017-10-12

Contour integration is the joining-up of local responses to parts of a contour into a continuous percept. In typical studies observers detect contours formed of discrete wavelets, presented against a background of random wavelets. This measures performance for detecting contours in the limiting external noise that background provides. Our novel task measures contour integration without requiring any background noise. This allowed us to perform noise-masking experiments using orientation and position noise. From these we measure the equivalent internal noise for contour integration. We found an orientation noise of 6° and position noise of 3 arcmin. Orientation noise was 2.6x higher in contour integration compared to an orientation discrimination control task. Comparing against a position discrimination task found position noise in contours to be 2.4x lower. This suggests contour integration involves intermediate processing that enhances the quality of element position representation at the expense of element orientation. Efficiency relative to the ideal observer was lower for the contour tasks (36% in orientation noise, 21% in position noise) compared to the controls (54% and 57%).

A Background Noise Reduction Technique Using Adaptive Noise Cancellation for Microphone Arrays

NASA Technical Reports Server (NTRS)

Spalt, Taylor B.; Fuller, Christopher R.; Brooks, Thomas F.; Humphreys, William M., Jr.; Brooks, Thomas F.

2011-01-01

Background noise in wind tunnel environments poses a challenge to acoustic measurements due to possible low or negative Signal to Noise Ratios (SNRs) present in the testing environment. This paper overviews the application of time domain Adaptive Noise Cancellation (ANC) to microphone array signals with an intended application of background noise reduction in wind tunnels. An experiment was conducted to simulate background noise from a wind tunnel circuit measured by an out-of-flow microphone array in the tunnel test section. A reference microphone was used to acquire a background noise signal which interfered with the desired primary noise source signal at the array. The technique s efficacy was investigated using frequency spectra from the array microphones, array beamforming of the point source region, and subsequent deconvolution using the Deconvolution Approach for the Mapping of Acoustic Sources (DAMAS) algorithm. Comparisons were made with the conventional techniques for improving SNR of spectral and Cross-Spectral Matrix subtraction. The method was seen to recover the primary signal level in SNRs as low as -29 dB and outperform the conventional methods. A second processing approach using the center array microphone as the noise reference was investigated for more general applicability of the ANC technique. It outperformed the conventional methods at the -29 dB SNR but yielded less accurate results when coherence over the array dropped. This approach could possibly improve conventional testing methodology but must be investigated further under more realistic testing conditions.

Music is as distracting as noise: the differential distraction of background music and noise on the cognitive test performance of introverts and extraverts.

PubMed

Furnham, Adrian; Strbac, Lisa

2002-02-20

Previous research has found that introverts' performance on complex cognitive tasks is more negatively affected by distracters, e.g. music and background television, than extraverts' performance. This study extended previous research by examining whether background noise would be as distracting as music. In the presence of silence, background garage music and office noise, 38 introverts and 38 extraverts carried out a reading comprehension task, a prose recall task and a mental arithmetic task. It was predicted that there would be an interaction between personality and background sound on all three tasks: introverts would do less well on all of the tasks than extraverts in the presence of music and noise but in silence performance would be the same. A significant interaction was found on the reading comprehension task only, although a trend for this effect was clearly present on the other two tasks. It was also predicted that there would be a main effect for background sound: performance would be worse in the presence of music and noise than silence. Results confirmed this prediction. These findings support the Eysenckian hypothesis of the difference in optimum cortical arousal in introverts and extraverts.

Background noise can enhance cortical auditory evoked potentials under certain conditions

PubMed Central

Papesh, Melissa A.; Billings, Curtis J.; Baltzell, Lucas S.

2017-01-01

Objective To use cortical auditory evoked potentials (CAEPs) to understand neural encoding in background noise and the conditions under which noise enhances CAEP responses. Methods CAEPs from 16 normal-hearing listeners were recorded using the speech syllable/ba/presented in quiet and speech-shaped noise at signal-to-noise ratios of 10 and 30 dB. The syllable was presented binaurally and monaurally at two presentation rates. Results The amplitudes of N1 and N2 peaks were often significantly enhanced in the presence of low-level background noise relative to quiet conditions, while P1 and P2 amplitudes were consistently reduced in noise. P1 and P2 amplitudes were significantly larger during binaural compared to monaural presentations, while N1 and N2 peaks were similar between binaural and monaural conditions. Conclusions Methodological choices impact CAEP peaks in very different ways. Negative peaks can be enhanced by background noise in certain conditions, while positive peaks are generally enhanced by binaural presentations. Significance Methodological choices significantly impact CAEPs acquired in quiet and in noise. If CAEPs are to be used as a tool to explore signal encoding in noise, scientists must be cognizant of how differences in acquisition and processing protocols selectively shape CAEP responses. PMID:25453611

Incorporating signal-dependent noise for hyperspectral target detection

NASA Astrophysics Data System (ADS)

Morman, Christopher J.; Meola, Joseph

2015-05-01

The majority of hyperspectral target detection algorithms are developed from statistical data models employing stationary background statistics or white Gaussian noise models. Stationary background models are inaccurate as a result of two separate physical processes. First, varying background classes often exist in the imagery that possess different clutter statistics. Many algorithms can account for this variability through the use of subspaces or clustering techniques. The second physical process, which is often ignored, is a signal-dependent sensor noise term. For photon counting sensors that are often used in hyperspectral imaging systems, sensor noise increases as the measured signal level increases as a result of Poisson random processes. This work investigates the impact of this sensor noise on target detection performance. A linear noise model is developed describing sensor noise variance as a linear function of signal level. The linear noise model is then incorporated for detection of targets using data collected at Wright Patterson Air Force Base.

Background noise in piezoresistive, electret condenser, and ceramic microphones.

PubMed

Zuckerwar, Allan J; Kuhn, Theodore R; Serbyn, Roman M

2003-06-01

Background noise studies have been extended from air condenser microphones to piezoresistive, electret condenser, and ceramic microphones. Theoretical models of the respective noise sources within each microphone are developed and are used to derive analytical expressions for the noise power spectral density for each type. Several additional noise sources for the piezoresistive and electret microphones, beyond what had previously been considered, were applied to the models and were found to contribute significantly to the total noise power spectral density. Experimental background noise measurements were taken using an upgraded acoustic isolation vessel and data acquisition system, and the results were compared to the theoretically obtained expressions. The models were found to yield power spectral densities consistent with the experimental results. The measurements reveal that the 1/f noise coefficient is strongly correlated with the diaphragm damping resistance, irrespective of the detection technology, i.e., air condenser, piezoresistive, etc. This conclusion has profound implications upon the expected 1/f noise component of micromachined (MEMS) microphones.

Assessment of the Influence of Background Noise on Escape-Maintained Problem Behavior and Pain Behavior in a Child with Williams Syndrome.

ERIC Educational Resources Information Center

O'Reilly, Mark F.; Lacey, Claire; Lancioni, Giulio E.

2000-01-01

A study examined the influence of background noise on levels of problem behavior and pain behavior under functional analysis conditions for a 5-year-old with Williams syndrome and hyperacusis. When the child was fitted with earplugs, there were substantial decreases in both problem and pain behavior under the background noise condition. (Contains…

Modeling Speech Level as a Function of Background Noise Level and Talker-to-Listener Distance for Talkers Wearing Hearing Protection Devices

ERIC Educational Resources Information Center

Bouserhal, Rachel E.; Bockstael, Annelies; MacDonald, Ewen; Falk, Tiago H.; Voix, Jérémie

2017-01-01

Purpose: Studying the variations in speech levels with changing background noise level and talker-to-listener distance for talkers wearing hearing protection devices (HPDs) can aid in understanding communication in background noise. Method: Speech was recorded using an intra-aural HPD from 12 different talkers at 5 different distances in 3…

Cascaded analysis of signal and noise propagation through a heterogeneous breast model.

PubMed

Mainprize, James G; Yaffe, Martin J

2010-10-01

The detectability of lesions in radiographic images can be impaired by patterns caused by the surrounding anatomic structures. The presence of such patterns is often referred to as anatomic noise. Others have previously extended signal and noise propagation theory to include variable background structure as an additional noise term and used in simulations for analysis by human and ideal observers. Here, the analytic forms of the signal and noise transfer are derived to obtain an exact expression for any input random distribution and the "power law" filter used to generate the texture of the tissue distribution. A cascaded analysis of propagation through a heterogeneous model is derived for x-ray projection through simulated heterogeneous backgrounds. This is achieved by considering transmission through the breast as a correlated amplification point process. The analytic forms of the cascaded analysis were compared to monoenergetic Monte Carlo simulations of x-ray propagation through power law structured backgrounds. As expected, it was found that although the quantum noise power component scales linearly with the x-ray signal, the anatomic noise will scale with the square of the x-ray signal. There was a good agreement between results obtained using analytic expressions for the noise power and those from Monte Carlo simulations for different background textures, random input functions, and x-ray fluence. Analytic equations for the signal and noise properties of heterogeneous backgrounds were derived. These may be used in direct analysis or as a tool to validate simulations in evaluating detectability.

Small Hot Jet Acoustic Rig Validation

NASA Technical Reports Server (NTRS)

Brown, Cliff; Bridges, James

2006-01-01

The Small Hot Jet Acoustic Rig (SHJAR), located in the Aeroacoustic Propulsion Laboratory (AAPL) at the NASA Glenn Research Center in Cleveland, Ohio, was commissioned in 2001 to test jet noise reduction concepts at low technology readiness levels (TRL 1-3) and develop advanced measurement techniques. The first series of tests on the SHJAR were designed to prove its capabilities and establish the quality of the jet noise data produced. Towards this goal, a methodology was employed dividing all noise sources into three categories: background noise, jet noise, and rig noise. Background noise was directly measured. Jet noise and rig noise were separated by using the distance and velocity scaling properties of jet noise. Effectively, any noise source that did not follow these rules of jet noise was labeled as rig noise. This method led to the identification of a high frequency noise source related to the Reynolds number. Experiments using boundary layer treatment and hot wire probes documented this noise source and its removal, allowing clean testing of low Reynolds number jets. Other tests performed characterized the amplitude and frequency of the valve noise, confirmed the location of the acoustic far field, and documented the background noise levels under several conditions. Finally, a full set of baseline data was acquired. This paper contains the methodology and test results used to verify the quality of the SHJAR rig.

Noise and signal properties in PSF-based fully 3D PET image reconstruction: an experimental evaluation

NASA Astrophysics Data System (ADS)

Tong, S.; Alessio, A. M.; Kinahan, P. E.

2010-03-01

The addition of accurate system modeling in PET image reconstruction results in images with distinct noise texture and characteristics. In particular, the incorporation of point spread functions (PSF) into the system model has been shown to visually reduce image noise, but the noise properties have not been thoroughly studied. This work offers a systematic evaluation of noise and signal properties in different combinations of reconstruction methods and parameters. We evaluate two fully 3D PET reconstruction algorithms: (1) OSEM with exact scanner line of response modeled (OSEM+LOR), (2) OSEM with line of response and a measured point spread function incorporated (OSEM+LOR+PSF), in combination with the effects of four post-reconstruction filtering parameters and 1-10 iterations, representing a range of clinically acceptable settings. We used a modified NEMA image quality (IQ) phantom, which was filled with 68Ge and consisted of six hot spheres of different sizes with a target/background ratio of 4:1. The phantom was scanned 50 times in 3D mode on a clinical system to provide independent noise realizations. Data were reconstructed with OSEM+LOR and OSEM+LOR+PSF using different reconstruction parameters, and our implementations of the algorithms match the vendor's product algorithms. With access to multiple realizations, background noise characteristics were quantified with four metrics. Image roughness and the standard deviation image measured the pixel-to-pixel variation; background variability and ensemble noise quantified the region-to-region variation. Image roughness is the image noise perceived when viewing an individual image. At matched iterations, the addition of PSF leads to images with less noise defined as image roughness (reduced by 35% for unfiltered data) and as the standard deviation image, while it has no effect on background variability or ensemble noise. In terms of signal to noise performance, PSF-based reconstruction has a 7% improvement in contrast recovery at matched ensemble noise levels and 20% improvement of quantitation SNR in unfiltered data. In addition, the relations between different metrics are studied. A linear correlation is observed between background variability and ensemble noise for all different combinations of reconstruction methods and parameters, suggesting that background variability is a reasonable surrogate for ensemble noise when multiple realizations of scans are not available.

Countermeasure against blinding attacks on low-noise detectors with a background-noise-cancellation scheme

NASA Astrophysics Data System (ADS)

Lee, Min Soo; Park, Byung Kwon; Woo, Min Ki; Park, Chang Hoon; Kim, Yong-Su; Han, Sang-Wook; Moon, Sung

2016-12-01

We developed a countermeasure against blinding attacks on low-noise detectors with a background-noise-cancellation scheme in quantum key distribution (QKD) systems. Background-noise cancellation includes self-differencing and balanced avalanche photon diode (APD) schemes and is considered a promising solution for low-noise APDs, which are critical components in high-performance QKD systems. However, its vulnerability to blinding attacks has been recently reported. In this work, we propose a countermeasure that prevents this potential security loophole from being used in detector blinding attacks. An experimental QKD setup is implemented and various tests are conducted to verify the feasibility and performance of the proposed method. The obtained measurement results show that the proposed scheme successfully detects occurring blinding-attack-based hacking attempts.

Variance analysis of x-ray CT sinograms in the presence of electronic noise background.

PubMed

Ma, Jianhua; Liang, Zhengrong; Fan, Yi; Liu, Yan; Huang, Jing; Chen, Wufan; Lu, Hongbing

2012-07-01

Low-dose x-ray computed tomography (CT) is clinically desired. Accurate noise modeling is a fundamental issue for low-dose CT image reconstruction via statistics-based sinogram restoration or statistical iterative image reconstruction. In this paper, the authors analyzed the statistical moments of low-dose CT data in the presence of electronic noise background. The authors first studied the statistical moment properties of detected signals in CT transmission domain, where the noise of detected signals is considered as quanta fluctuation upon electronic noise background. Then the authors derived, via the Taylor expansion, a new formula for the mean-variance relationship of the detected signals in CT sinogram domain, wherein the image formation becomes a linear operation between the sinogram data and the unknown image, rather than a nonlinear operation in the CT transmission domain. To get insight into the derived new formula by experiments, an anthropomorphic torso phantom was scanned repeatedly by a commercial CT scanner at five different mAs levels from 100 down to 17. The results demonstrated that the electronic noise background is significant when low-mAs (or low-dose) scan is performed. The influence of the electronic noise background should be considered in low-dose CT imaging.

Variance analysis of x-ray CT sinograms in the presence of electronic noise background

PubMed Central

Ma, Jianhua; Liang, Zhengrong; Fan, Yi; Liu, Yan; Huang, Jing; Chen, Wufan; Lu, Hongbing

2012-01-01

Purpose: Low-dose x-ray computed tomography (CT) is clinically desired. Accurate noise modeling is a fundamental issue for low-dose CT image reconstruction via statistics-based sinogram restoration or statistical iterative image reconstruction. In this paper, the authors analyzed the statistical moments of low-dose CT data in the presence of electronic noise background. Methods: The authors first studied the statistical moment properties of detected signals in CT transmission domain, where the noise of detected signals is considered as quanta fluctuation upon electronic noise background. Then the authors derived, via the Taylor expansion, a new formula for the mean–variance relationship of the detected signals in CT sinogram domain, wherein the image formation becomes a linear operation between the sinogram data and the unknown image, rather than a nonlinear operation in the CT transmission domain. To get insight into the derived new formula by experiments, an anthropomorphic torso phantom was scanned repeatedly by a commercial CT scanner at five different mAs levels from 100 down to 17. Results: The results demonstrated that the electronic noise background is significant when low-mAs (or low-dose) scan is performed. Conclusions: The influence of the electronic noise background should be considered in low-dose CT imaging. PMID:22830738

Thresholding of auditory cortical representation by background noise

PubMed Central

Liang, Feixue; Bai, Lin; Tao, Huizhong W.; Zhang, Li I.; Xiao, Zhongju

2014-01-01

It is generally thought that background noise can mask auditory information. However, how the noise specifically transforms neuronal auditory processing in a level-dependent manner remains to be carefully determined. Here, with in vivo loose-patch cell-attached recordings in layer 4 of the rat primary auditory cortex (A1), we systematically examined how continuous wideband noise of different levels affected receptive field properties of individual neurons. We found that the background noise, when above a certain critical/effective level, resulted in an elevation of intensity threshold for tone-evoked responses. This increase of threshold was linearly dependent on the noise intensity above the critical level. As such, the tonal receptive field (TRF) of individual neurons was translated upward as an entirety toward high intensities along the intensity domain. This resulted in preserved preferred characteristic frequency (CF) and the overall shape of TRF, but reduced frequency responding range and an enhanced frequency selectivity for the same stimulus intensity. Such translational effects on intensity threshold were observed in both excitatory and fast-spiking inhibitory neurons, as well as in both monotonic and nonmonotonic (intensity-tuned) A1 neurons. Our results suggest that in a noise background, fundamental auditory representations are modulated through a background level-dependent linear shifting along intensity domain, which is equivalent to reducing stimulus intensity. PMID:25426029

Evaluation of the effectiveness of Gaussian filtering in distinguishing punctate synaptic signals from background noise during image analysis.

PubMed

Iwabuchi, Sadahiro; Kakazu, Yasuhiro; Koh, Jin-Young; Harata, N Charles

2014-02-15

Images in biomedical imaging research are often affected by non-specific background noise. This poses a serious problem when the noise overlaps with specific signals to be quantified, e.g. for their number and intensity. A simple and effective means of removing background noise is to prepare a filtered image that closely reflects background noise and to subtract it from the original unfiltered image. This approach is in common use, but its effectiveness in identifying and quantifying synaptic puncta has not been characterized in detail. We report on our assessment of the effectiveness of isolating punctate signals from diffusely distributed background noise using one variant of this approach, "Difference of Gaussian(s) (DoG)" which is based on a Gaussian filter. We evaluated immunocytochemically stained, cultured mouse hippocampal neurons as an example, and provided the rationale for choosing specific parameter values for individual steps in detecting glutamatergic nerve terminals. The intensity and width of the detected puncta were proportional to those obtained by manual fitting of two-dimensional Gaussian functions to the local information in the original image. DoG was compared with the rolling-ball method, using biological data and numerical simulations. Both methods removed background noise, but differed slightly with respect to their efficiency in discriminating neighboring peaks, as well as their susceptibility to high-frequency noise and variability in object size. DoG will be useful in detecting punctate signals, once its characteristics are examined quantitatively by experimenters. Copyright © 2013 Elsevier B.V. All rights reserved.

Intergenerational preferences for radio loudness during automobile driving.

PubMed

Hanser, Frederick Howard Bateman; Adjei Boakye, Eric; Mikulec, Anthony Alan

2017-07-01

The comparative contribution to human noise exposure from the vehicular radio is unknown, as are the radio volume preferences of different generations when driving an automobile. A single vehicle was used to measure radio listening level in decibels of three generations (age 16-17 years, age 32-50 years, and age 51-73 years) in various conditions, ranging from engine off with windows closed to 60 miles per hour (mph) with windows open. No differences in radio loudness based on the sex of the driver were found. Statistically significant differences were identified in preferred signal to noise ratio among multiple vehicular paradigms, with the youngest generation preferring the largest signal to noise ratio in conditions with low background noise. The youngest generation favored the largest signal to noise ratio (radio level above background noise), a preference which waned with increasing background noise. Copyright © 2017 Elsevier B.V. All rights reserved.

Noise covariance incorporated MEG-MUSIC algorithm: a method for multiple-dipole estimation tolerant of the influence of background brain activity.

PubMed

Sekihara, K; Poeppel, D; Marantz, A; Koizumi, H; Miyashita, Y

1997-09-01

This paper proposes a method of localizing multiple current dipoles from spatio-temporal biomagnetic data. The method is based on the multiple signal classification (MUSIC) algorithm and is tolerant of the influence of background brain activity. In this method, the noise covariance matrix is estimated using a portion of the data that contains noise, but does not contain any signal information. Then, a modified noise subspace projector is formed using the generalized eigenvectors of the noise and measured-data covariance matrices. The MUSIC localizer is calculated using this noise subspace projector and the noise covariance matrix. The results from a computer simulation have verified the effectiveness of the method. The method was then applied to source estimation for auditory-evoked fields elicited by syllable speech sounds. The results strongly suggest the method's effectiveness in removing the influence of background activity.

The effects of background noise on cognitive performance during a 70 hour simulation of conditions aboard the International Space Station.

PubMed

Smith, D G; Baranski, J V; Thompson, M M; Abel, S M

2003-01-01

A total of twenty-five subjects were cloistered for a period of 70 hours, five at a time, in a hyperbaric chamber modified to simulate the conditions aboard the International Space Station (ISS). A recording of 72 dBA background noise from the ISS service module was used to simulate noise conditions on the ISS. Two groups experienced the background noise throughout the experiment, two other groups experienced the noise only during the day, and one control group was cloistered in a quiet environment. All subjects completed a battery of cognitive tests nine times throughout the experiment. The data showed little or no effect of noise on reasoning, perceptual decision-making, memory, vigilance, mood, or subjective indices of fatigue. Our results suggest that the level of noise on the space station should not affect cognitive performance, at least over a period of several days.

Dolphins Adjust Species-Specific Frequency Parameters to Compensate for Increasing Background Noise

PubMed Central

Papale, Elena; Gamba, Marco; Perez-Gil, Monica; Martin, Vidal Martel; Giacoma, Cristina

2015-01-01

An increase in ocean noise levels could interfere with acoustic communication of marine mammals. In this study we explored the effects of anthropogenic and natural noise on the acoustic properties of a dolphin communication signal, the whistle. A towed array with four elements was used to record environmental background noise and whistles of short-beaked common-, Atlantic spotted- and striped-dolphins in the Canaries archipelago. Four frequency parameters were measured from each whistle, while Sound Pressure Levels (SPL) of the background noise were measured at the central frequencies of seven one-third octave bands, from 5 to 20 kHz. Results show that dolphins increase the whistles’ frequency parameters with lower variability in the presence of anthropogenic noise, and increase the end frequency of their whistles when confronted with increasing natural noise. This study provides the first evidence that the synergy among SPLs has a role in shaping the whistles' structure of these three species, with respect to both natural and anthropogenic noise. PMID:25853825

When noise is beneficial for sensory encoding: Noise adaptation can improve face processing.

PubMed

Menzel, Claudia; Hayn-Leichsenring, Gregor U; Redies, Christoph; Németh, Kornél; Kovács, Gyula

2017-10-01

The presence of noise usually impairs the processing of a stimulus. Here, we studied the effects of noise on face processing and show, for the first time, that adaptation to noise patterns has beneficial effects on face perception. We used noiseless faces that were either surrounded by random noise or presented on a uniform background as stimuli. In addition, the faces were either preceded by noise adaptors or not. Moreover, we varied the statistics of the noise so that its spectral slope either matched that of the faces or it was steeper or shallower. Results of parallel ERP recordings showed that the background noise reduces the amplitude of the face-evoked N170, indicating less intensive face processing. Adaptation to a noise pattern, however, led to reduced P1 and enhanced N170 amplitudes as well as to a better behavioral performance in two of the three noise conditions. This effect was also augmented by the presence of background noise around the target stimuli. Additionally, the spectral slope of the noise pattern affected the size of the P1, N170 and P2 amplitudes. We reason that the observed effects are due to the selective adaptation of noise-sensitive neurons present in the face-processing cortical areas, which may enhance the signal-to-noise-ratio. Copyright © 2017 Elsevier Inc. All rights reserved.

Quantum noise properties of CT images with anatomical textured backgrounds across reconstruction algorithms: FBP and SAFIRE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Solomon, Justin, E-mail: justin.solomon@duke.edu; Samei, Ehsan

2014-09-15

Purpose: Quantum noise properties of CT images are generally assessed using simple geometric phantoms with uniform backgrounds. Such phantoms may be inadequate when assessing nonlinear reconstruction or postprocessing algorithms. The purpose of this study was to design anatomically informed textured phantoms and use the phantoms to assess quantum noise properties across two clinically available reconstruction algorithms, filtered back projection (FBP) and sinogram affirmed iterative reconstruction (SAFIRE). Methods: Two phantoms were designed to represent lung and soft-tissue textures. The lung phantom included intricate vessel-like structures along with embedded nodules (spherical, lobulated, and spiculated). The soft tissue phantom was designed based onmore » a three-dimensional clustered lumpy background with included low-contrast lesions (spherical and anthropomorphic). The phantoms were built using rapid prototyping (3D printing) technology and, along with a uniform phantom of similar size, were imaged on a Siemens SOMATOM Definition Flash CT scanner and reconstructed with FBP and SAFIRE. Fifty repeated acquisitions were acquired for each background type and noise was assessed by estimating pixel-value statistics, such as standard deviation (i.e., noise magnitude), autocorrelation, and noise power spectrum. Noise stationarity was also assessed by examining the spatial distribution of noise magnitude. The noise properties were compared across background types and between the two reconstruction algorithms. Results: In FBP and SAFIRE images, noise was globally nonstationary for all phantoms. In FBP images of all phantoms, and in SAFIRE images of the uniform phantom, noise appeared to be locally stationary (within a reasonably small region of interest). Noise was locally nonstationary in SAFIRE images of the textured phantoms with edge pixels showing higher noise magnitude compared to pixels in more homogenous regions. For pixels in uniform regions, noise magnitude was reduced by an average of 60% in SAFIRE images compared to FBP. However, for edge pixels, noise magnitude ranged from 20% higher to 40% lower in SAFIRE images compared to FBP. SAFIRE images of the lung phantom exhibited distinct regions with varying noise texture (i.e., noise autocorrelation/power spectra). Conclusions: Quantum noise properties observed in uniform phantoms may not be representative of those in actual patients for nonlinear reconstruction algorithms. Anatomical texture should be considered when evaluating the performance of CT systems that use such nonlinear algorithms.« less

Radio Astronomy Explorer (RAE) 1 observations of terrestrial radio noise

NASA Technical Reports Server (NTRS)

Herman, J. R.; Caruso, J. A.

1971-01-01

Radio Astonomy Explorer (RAE) 1 data are analyzed to establish characteristics of HF terrestrial radio noise at an altitude of about 6000 km. Time and frequency variations in amplitude of the observed noise well above cosmic noise background are explained on the basis of temporal and spatial variations in ionospheric critical frequency coupled with those in noise source distributions. It is shown that terrestrial noise regularly breaks through the ionosphere and reaches RAE with magnitudes 15 or more db higher than cosmic noise background. Maximum terrestrial noise is observed when RAE is over the dark side of the Earth in the neighborhood of equatorial continental land masses where thunderstorms occur most frequently. The observed noise level is 30-40 db lower with RAE over oceans.

CS2 analysis in presence of non-Gaussian background noise - Effect on traditional estimators and resilience of log-envelope indicators

NASA Astrophysics Data System (ADS)

Borghesani, P.; Antoni, J.

2017-06-01

Second-order cyclostationary (CS2) analysis has become popular in the field of machine diagnostics and a series of digital signal processing techniques have been developed to extract CS2 components from the background noise. Among those techniques, squared envelope spectrum (SES) and cyclic modulation spectrum (CMS) have gained popularity thanks to their high computational efficiency and simple implementation. The effectiveness of CMS and SES has been previously quantified based on the hypothesis of Gaussian background noise and has led to statistical tests for the presence of CS2 peaks in squared envelope spectra and cyclic modulation spectra. However a recently established link of CMS with SES and of SES with kurtosis has exposed a potential weakness of those indicators in the case of highly leptokurtic background noise. This case is often present in practice when the machine is subjected to highly impulsive phenomena, either due to harsh operating conditions or to electric noise generated by power electronics and captured by the sensor. This study investigates and quantifies for the first time the effect of leptokurtic noise on the capabilities of SES and CMS, by analysing three progressively harsh situations: high kurtosis, infinite kurtosis and alpha-stable background noise (for which even first and second-order moments are not defined). Then the resilience of a recently proposed family of CS2 indicators, based on the log-envelope, is verified analytically, numerically and experimentally in the case of highly leptokurtic noise.

Improvement of LOD in Fluorescence Detection with Spectrally Nonuniform Background by Optimization of Emission Filtering.

PubMed

Galievsky, Victor A; Stasheuski, Alexander S; Krylov, Sergey N

2017-10-17

The limit-of-detection (LOD) in analytical instruments with fluorescence detection can be improved by reducing noise of optical background. Efficiently reducing optical background noise in systems with spectrally nonuniform background requires complex optimization of an emission filter-the main element of spectral filtration. Here, we introduce a filter-optimization method, which utilizes an expression for the signal-to-noise ratio (SNR) as a function of (i) all noise components (dark, shot, and flicker), (ii) emission spectrum of the analyte, (iii) emission spectrum of the optical background, and (iv) transmittance spectrum of the emission filter. In essence, the noise components and the emission spectra are determined experimentally and substituted into the expression. This leaves a single variable-the transmittance spectrum of the filter-which is optimized numerically by maximizing SNR. Maximizing SNR provides an accurate way of filter optimization, while a previously used approach based on maximizing a signal-to-background ratio (SBR) is the approximation that can lead to much poorer LOD specifically in detection of fluorescently labeled biomolecules. The proposed filter-optimization method will be an indispensable tool for developing new and improving existing fluorescence-detection systems aiming at ultimately low LOD.

Evaluations of indoor noise criteria systems based on human response

NASA Astrophysics Data System (ADS)

Bowden, Erica E.; Wang, Lily M.

2005-09-01

The goal of this research is to examine human response to background noise, and relate results to indoor noise criteria. In previous work by the authors, subjects completed perception surveys, typing tasks, and proofreading tasks under typical heating, ventilating, and air-conditioning (HVAC) noise conditions. Results were correlated with commonly used indoor noise criteria systems including noise criteria (NC), room criteria (RC) and others. The findings suggested that the types of tasks used and the length of exposure can impact the results. To examine these two issues, the authors conducted a new study in which each test subject completed 38 total hours of testing over multiple days. Subjects were exposed to several background noise exposures over 20, 40, 80, and 240 minute trials. During the trials, subjects completed a variety of performance tasks and answered questions about their perception of the noise, the thermal environment, and various other factors. Findings from this study were used to determine optimum testing conditions for on-going research examining the effects of tonal or fluctuating background noise on performance, annoyance, and spectral perception. Results are being used to evaluate the effectiveness of commonly used indoor noise criteria systems. [Work supported by INCE and ASHRAE.

The amount of decrease of the background white noise intensity as a cue for differentiation training.

PubMed

Zieliński, K

1981-01-01

The course of differentiation learning, using the conditioned emotional response (CER) method, was investigated in two groups of 16 rats. The discriminative stimuli consisted of decreases in the 80 dB background white noise to either 70 dB or 60 dB. Differentiation learning was more efficient with the larger decrease of background noise intensity as the CS(+) and the smaller decrease as the CS(-) than vice versa.

Effects of Background Noise on Cortical Encoding of Speech in Autism Spectrum Disorders

ERIC Educational Resources Information Center

Russo, Nicole; Zecker, Steven; Trommer, Barbara; Chen, Julia; Kraus, Nina

2009-01-01

This study provides new evidence of deficient auditory cortical processing of speech in noise in autism spectrum disorders (ASD). Speech-evoked responses (approximately 100-300 ms) in quiet and background noise were evaluated in typically-developing (TD) children and children with ASD. ASD responses showed delayed timing (both conditions) and…

Noise in the Classroom: Understanding the Problem.

ERIC Educational Resources Information Center

Lilly, Jerry G.

2000-01-01

Presents guidelines for designing classroom HVAC systems that will be able to achieve lower background noise levels that conform to the NC-30 background noise rating level. Guidelines for both central and dedicated systems are offered revealing that the use of conventional HVAC system components can be used to achieve sound levels comparable to…

Speaking up: Killer whales (Orcinus orca) increase their call amplitude in response to vessel noise.

PubMed

Holt, Marla M; Noren, Dawn P; Veirs, Val; Emmons, Candice K; Veirs, Scott

2009-01-01

This study investigated the effects of anthropogenic sound exposure on the vocal behavior of free-ranging killer whales. Endangered Southern Resident killer whales inhabit areas including the urban coastal waters of Puget Sound near Seattle, WA, where anthropogenic sounds are ubiquitous, particularly those from motorized vessels. A calibrated recording system was used to measure killer whale call source levels and background noise levels (1-40 kHz). Results show that whales increased their call amplitude by 1 dB for every 1 dB increase in background noise levels. Furthermore, nearby vessel counts were positively correlated with these observed background noise levels.

The invariant statistical rule of aerosol scattering pulse signal modulated by random noise

NASA Astrophysics Data System (ADS)

Yan, Zhen-gang; Bian, Bao-Min; Yang, Juan; Peng, Gang; Li, Zhen-hua

2010-11-01

A model of the random background noise acting on particle signals is established to study the impact of the background noise of the photoelectric sensor in the laser airborne particle counter on the statistical character of the aerosol scattering pulse signals. The results show that the noises broaden the statistical distribution of the particle's measurement. Further numerical research shows that the output of the signal amplitude still has the same distribution when the airborne particle with the lognormal distribution was modulated by random noise which has lognormal distribution. Namely it follows the statistics law of invariance. Based on this model, the background noise of photoelectric sensor and the counting distributions of random signal for aerosol's scattering pulse are obtained and analyzed by using a high-speed data acquisition card PCI-9812. It is found that the experiment results and simulation results are well consistent.

Binaural speech discrimination under noise in hearing-impaired listeners

NASA Technical Reports Server (NTRS)

Kumar, K. V.; Rao, A. B.

1988-01-01

This paper presents the results of an assessment of speech discrimination by hearing-impaired listeners (sensori-neural, conductive, and mixed groups) under binaural free-field listening in the presence of background noise. Subjects with pure-tone thresholds greater than 20 dB in 0.5, 1.0 and 2.0 kHz were presented with a version of the W-22 list of phonetically balanced words under three conditions: (1) 'quiet', with the chamber noise below 28 dB and speech at 60 dB; (2) at a constant S/N ratio of +10 dB, and with a background white noise at 70 dB; and (3) same as condition (2), but with the background noise at 80 dB. The mean speech discrimination scores decreased significantly with noise in all groups. However, the decrease in binaural speech discrimination scores with an increase in hearing impairment was less for material presented under the noise conditions than for the material presented in quiet.

Noise analysis of the seismic system employed in the northern and southern California seismic nets

USGS Publications Warehouse

Eaton, J.P.

1984-01-01

The seismic networks have been designed and operated to support recording on Develocorders (less than 40db dynamic range) and analog magnetic tape (about 50 db dynamic range). The principal analysis of the records has been based on Develocorder films; and background earth noise levels have been adjusted to be about 1 to 2 mm p-p on the film readers. Since the traces are separated by only 10 to 12 mm on the reader screen, they become hopelessly tangled when signal amplitudes on several adjacent traces exceed 10 to 20 mm p-p. Thus, the background noise level is hardly more than 20 db below the level of largest readable signals. The situation is somewhat better on tape playbacks, but the high level of background noise set to accomodate processing from film records effectively limits the range of maximum-signal to background-earth-noise on high gain channels to a little more than 30 db. Introduction of the PDP 11/44 seismic data acquisition system has increased the potential dynamic range of recorded network signals to more than 60 db. To make use of this increased dynamic range we must evaluate the characteristics and performance of the seismic system. In particular, we must determine whether the electronic noise in the system is or can be made sufficiently low so that background earth noise levels can be lowered significantly to take advantage of the increased dynamic range of the digital recording system. To come to grips with the complex problem of system noise, we have carried out a number of measurements and experiments to evaluate critical components of the system as well as to determine the noise characteristics of the system as a whole.

Noise levels in an urban Asian school environment

PubMed Central

Chan, Karen M.K.; Li, Chi Mei; Ma, Estella P.M.; Yiu, Edwin M.L.; McPherson, Bradley

2015-01-01

Background noise is known to adversely affect speech perception and speech recognition. High levels of background noise in school classrooms may affect student learning, especially for those pupils who are learning in a second language. The current study aimed to determine the noise level and teacher speech-to-noise ratio (SNR) in Hong Kong classrooms. Noise level was measured in 146 occupied classrooms in 37 schools, including kindergartens, primary schools, secondary schools and special schools, in Hong Kong. The mean noise levels in occupied kindergarten, primary school, secondary school and special school classrooms all exceeded recommended maximum noise levels, and noise reduction measures were seldom used in classrooms. The measured SNRs were not optimal and could have adverse implications for student learning and teachers’ vocal health. Schools in urban Asian environments are advised to consider noise reduction measures in classrooms to better comply with recommended maximum noise levels for classrooms. PMID:25599758

Noise levels in an urban Asian school environment.

PubMed

Chan, Karen M K; Li, Chi Mei; Ma, Estella P M; Yiu, Edwin M L; McPherson, Bradley

2015-01-01

Background noise is known to adversely affect speech perception and speech recognition. High levels of background noise in school classrooms may affect student learning, especially for those pupils who are learning in a second language. The current study aimed to determine the noise level and teacher speech-to-noise ratio (SNR) in Hong Kong classrooms. Noise level was measured in 146 occupied classrooms in 37 schools, including kindergartens, primary schools, secondary schools and special schools, in Hong Kong. The mean noise levels in occupied kindergarten, primary school, secondary school and special school classrooms all exceeded recommended maximum noise levels, and noise reduction measures were seldom used in classrooms. The measured SNRs were not optimal and could have adverse implications for student learning and teachers' vocal health. Schools in urban Asian environments are advised to consider noise reduction measures in classrooms to better comply with recommended maximum noise levels for classrooms.

Low-Arousal Speech Noise Improves Performance in N-Back Task: An ERP Study

PubMed Central

Zhang, Dandan; Jin, Yi; Luo, Yuejia

2013-01-01

The relationship between noise and human performance is a crucial topic in ergonomic research. However, the brain dynamics of the emotional arousal effects of background noises are still unclear. The current study employed meaningless speech noises in the n-back working memory task to explore the changes of event-related potentials (ERPs) elicited by the noises with low arousal level vs. high arousal level. We found that the memory performance in low arousal condition were improved compared with the silent and the high arousal conditions; participants responded more quickly and had larger P2 and P3 amplitudes in low arousal condition while the performance and ERP components showed no significant difference between high arousal and silent conditions. These findings suggested that the emotional arousal dimension of background noises had a significant influence on human working memory performance, and that this effect was independent of the acoustic characteristics of noises (e.g., intensity) and the meaning of speech materials. The current findings improve our understanding of background noise effects on human performance and lay the ground for the investigation of patients with attention deficits. PMID:24204607

Acoustic treatment of the NASA Langley 4- by 7-meter tunnel: A feasibility study

NASA Technical Reports Server (NTRS)

Yu, J. C.; Abrahamson, A. L.

1986-01-01

A feasibility study for upgrading the NASA Langley 4- by 7-Meter Tunnel so that it may be used for aeroacoustic research related to helicopters is described. The requirements for noise research leading to the design of the next generation of helicopters impose a set of acoustic test criteria that no existing wind tunnel in the United States can presently meet. Included in this feasibility study are the following considerations: (1) an evaluation of general wind-tunnel requirements and desired tunnel background noise levels for helicopter aeroacoustic research; (2) an assessment of the present acoustic environment for testing model rotors; (3) a diagnostic investigation of tunnel background noise sources and paths; (4) acoustic treatment options for tunnel background noise reduction and a trade-off study between these options; (5) an engineering feasibility assessment of the selected option; and (6) an integrated analysis of study components and recommendations of treatment for an approach to meet the tunnel background noise reduction goal. It is concluded that the Langley 4- by 7-Meter Tunnel is a fundamentally suitable facility for helicopter aeroacoustic research. It is also concluded that acoustic treatment of this facility for meeting the required tunnel background noise goal can be accomplished technically at reasonable risk and cost.

An improved algorithm of laser spot center detection in strong noise background

NASA Astrophysics Data System (ADS)

Zhang, Le; Wang, Qianqian; Cui, Xutai; Zhao, Yu; Peng, Zhong

2018-01-01

Laser spot center detection is demanded in many applications. The common algorithms for laser spot center detection such as centroid and Hough transform method have poor anti-interference ability and low detection accuracy in the condition of strong background noise. In this paper, firstly, the median filtering was used to remove the noise while preserving the edge details of the image. Secondly, the binarization of the laser facula image was carried out to extract target image from background. Then the morphological filtering was performed to eliminate the noise points inside and outside the spot. At last, the edge of pretreated facula image was extracted and the laser spot center was obtained by using the circle fitting method. In the foundation of the circle fitting algorithm, the improved algorithm added median filtering, morphological filtering and other processing methods. This method could effectively filter background noise through theoretical analysis and experimental verification, which enhanced the anti-interference ability of laser spot center detection and also improved the detection accuracy.

The Effect of Background Noise on Intelligibility of Dysphonic Speech

ERIC Educational Resources Information Center

Ishikawa, Keiko; Boyce, Suzanne; Kelchner, Lisa; Powell, Maria Golla; Schieve, Heidi; de Alarcon, Alessandro; Khosla, Sid

2017-01-01

Purpose: The aim of this study is to determine the effect of background noise on the intelligibility of dysphonic speech and to examine the relationship between intelligibility in noise and an acoustic measure of dysphonia--cepstral peak prominence (CPP). Method: A study of speech perception was conducted using speech samples from 6 adult speakers…

A novel method to remove GPR background noise based on the similarity of non-neighboring regions

NASA Astrophysics Data System (ADS)

Montiel-Zafra, V.; Canadas-Quesada, F. J.; Vera-Candeas, P.; Ruiz-Reyes, N.; Rey, J.; Martinez, J.

2017-09-01

Ground penetrating radar (GPR) is a non-destructive technique that has been widely used in many areas of research, such as landmine detection or subsurface anomalies, where it is required to locate targets embedded within a background medium. One of the major challenges in the research of GPR data remains the improvement of the image quality of stone materials by means of detection of true anisotropies since most of the errors are caused by an incorrect interpretation by the users. However, it is complicated due to the interference of the horizontal background noise, e.g., the air-ground interface, that reduces the high-resolution quality of radargrams. Thus, weak or deep anisotropies are often masked by this type of noise. In order to remove the background noise obtained by GPR, this work proposes a novel background removal method assuming that the horizontal noise shows repetitive two-dimensional regions along the movement of the GPR antenna. Specifically, the proposed method, based on the non-local similarity of regions over the distance, computes similarities between different regions of the same depth in order to identify most repetitive regions using a criterion to avoid closer regions. Evaluations are performed using a set of synthetic and real GPR data. Experimental results show that the proposed method obtains promising results compared to the classic background removal techniques and the most recently published background removal methods.

Verification of the directivity index and other measures of directivity in predicting directional benefit

NASA Astrophysics Data System (ADS)

Dittberner, Andrew; Bentler, Ruth

2005-09-01

The relationship between various directivity measures and subject performance with directional microphone hearing aids was determined. Test devices included first- and second-order directional microphones. Recordings of sentences and noise (Hearing in Noise Test, HINT) were made through each test device in simple, complex, and anisotropic background noise conditions. Twenty-six subjects, with normal hearing, were administered the HINT test recordings, and directional benefit was computed. These measures were correlated to theoretical, free-field, and KEMAR DI values, as well as front-to-back ratios, in situ SNRs, and a newly proposed Db-SNR, wherein a predictive value of the SNR improvement is calculated as a function of the noise source incidence. The different predictive scores showed high correlation to the measured directional benefit scores in the complex (diffuse-like) background noise condition (r=0.89-0.97, p<0.05) but not across all background noise conditions (r=0.45-0.97, p<0.05). The Db-SNR approach and the in situ SNR measures provided excellent prediction of subject performance in all background noise conditions (0.85-0.97, p<0.05) None of the predictive measures could account for the effects of reverberation on the speech signal (r=0.35-0.40, p<0.05).

GRC-11-02-17-WindTunnel-9x15-001

NASA Image and Video Library

2017-11-02

The Aerosciences Evaluation and Test Capabilities (AETC) Portfolio implemented the Capability Challenge to “Reduce Background Noise Levels for Engine Efficiency Measurements at the NASA Glenn 9x15 Low Speed Wind Tunnel”. The 9x15 Low Speed Wind Tunnel Acoustic Improvements animation documents the acoustic modifications being made to the 9x15 leg of the wind tunnel to reduce background noise levels. A brief history of the 9x15, research testing performed in the wind tunnel, the need to reduce background noise, and the five state of the art acoustic design modifications are documented in the animation. The expected noise reduction is presented audibly and the resulting benefit to NASA is also defined.

Suppression of background noise in a transonic wind-tunnel test section

NASA Technical Reports Server (NTRS)

Schutzenhofer, L. A.; Howard, P. W.

1975-01-01

Some exploratory tests were recently performed in the transonic test section of the NASA Marshall Space Flight Center 14-in. wind tunnel to suppress the background noise. In these tests, the perforated walls of the test section were covered with fine wire screens. The screens eliminated the edge tones generated by the holes in the perforated walls and significantly reduced the tunnel background noise. The tunnel noise levels were reduced to such a degree by this simple modification at Mach numbers 0.75, 0.9, 1.1, 1.2, and 1.46 that the fluctuating pressure levels of a turbulent boundary layer could be measured on a 5-deg half-angle cone.

The Effects of Different Noise Types on Heart Rate Variability in Men

PubMed Central

Sim, Chang Sun; Sung, Joo Hyun; Cheon, Sang Hyeon; Lee, Jang Myung; Lee, Jae Won

2015-01-01

Purpose To determine the impact of noise on heart rate variability (HRV) in men, with a focus on the noise type rather than on noise intensity. Materials and Methods Forty college-going male volunteers were enrolled in this study and were randomly divided into four groups according to the type of noise they were exposed to: background, traffic, speech, or mixed (traffic and speech) noise. All groups except the background group (35 dB) were exposed to 45 dB sound pressure levels. We collected data on age, smoking status, alcohol consumption, and disease status from responses to self-reported questionnaires and medical examinations. We also measured HRV parameters and blood pressure levels before and after exposure to noise. The HRV parameters were evaluated while patients remained seated for 5 minutes, and frequency and time domain analyses were then performed. Results After noise exposure, only the speech noise group showed a reduced low frequency (LF) value, reflecting the activity of both the sympathetic and parasympathetic nervous systems. The low-to-high frequency (LF/HF) ratio, which reflected the activity of the autonomic nervous system (ANS), became more stable, decreasing from 5.21 to 1.37; however, this change was not statistically significant. Conclusion These results indicate that 45 dB(A) of noise, 10 dB(A) higher than background noise, affects the ANS. Additionally, the impact on HRV activity might differ according to the noise quality. Further studies will be required to ascertain the role of noise type. PMID:25510770

The effects of different noise types on heart rate variability in men.

PubMed

Sim, Chang Sun; Sung, Joo Hyun; Cheon, Sang Hyeon; Lee, Jang Myung; Lee, Jae Won; Lee, Jiho

2015-01-01

To determine the impact of noise on heart rate variability (HRV) in men, with a focus on the noise type rather than on noise intensity. Forty college-going male volunteers were enrolled in this study and were randomly divided into four groups according to the type of noise they were exposed to: background, traffic, speech, or mixed (traffic and speech) noise. All groups except the background group (35 dB) were exposed to 45 dB sound pressure levels. We collected data on age, smoking status, alcohol consumption, and disease status from responses to self-reported questionnaires and medical examinations. We also measured HRV parameters and blood pressure levels before and after exposure to noise. The HRV parameters were evaluated while patients remained seated for 5 minutes, and frequency and time domain analyses were then performed. After noise exposure, only the speech noise group showed a reduced low frequency (LF) value, reflecting the activity of both the sympathetic and parasympathetic nervous systems. The low-to-high frequency (LF/HF) ratio, which reflected the activity of the autonomic nervous system (ANS), became more stable, decreasing from 5.21 to 1.37; however, this change was not statistically significant. These results indicate that 45 dB(A) of noise, 10 dB(A) higher than background noise, affects the ANS. Additionally, the impact on HRV activity might differ according to the noise quality. Further studies will be required to ascertain the role of noise type.

Measurement of speech levels in the presence of time varying background noise

NASA Technical Reports Server (NTRS)

Pearsons, K. S.; Horonjeff, R.

1982-01-01

Short-term speech level measurements which could be used to note changes in vocal effort in a time varying noise environment were studied. Knowing the changes in speech level would in turn allow prediction of intelligibility in the presence of aircraft flyover noise. Tests indicated that it is possible to use two second samples of speech to estimate long term root mean square speech levels. Other tests were also performed in which people read out loud during aircraft flyover noise. Results of these tests indicate that people do indeed raise their voice during flyovers at a rate of about 3-1/2 dB for each 10 dB increase in background level. This finding is in agreement with other tests of speech levels in the presence of steady state background noise.

Energy Measurement Studies for CO2 Measurement with a Coherent Doppler Lidar System

NASA Technical Reports Server (NTRS)

Beyon, Jeffrey Y.; Koch, Grady J.; Vanvalkenburg, Randal L.; Yu, Jirong; Singh, Upendra N.; Kavaya, Michael J.

2010-01-01

The accurate measurement of energy in the application of lidar system for CO2 measurement is critical. Different techniques of energy estimation in the online and offline pulses are investigated for post processing of lidar returns. The cornerstone of the techniques is the accurate estimation of the spectrum of lidar signal and background noise. Since the background noise is not the ideal white Gaussian noise, simple average level estimation of noise level is not well fit in the energy estimation of lidar signal and noise. A brief review of the methods is presented in this paper.

Planets as background noise sources in free space optical communications

NASA Technical Reports Server (NTRS)

Katz, J.

1986-01-01

Background noise generated by planets is the dominant noise source in most deep space direct detection optical communications systems. Earlier approximate analyses of this problem are based on simplified blackbody calculations and can yield results that may be inaccurate by up to an order of magnitude. Various other factors that need to be taken into consideration, such as the phase angle and the actual spectral dependence of the planet albedo, in order to obtain a more accurate estimate of the noise magnitude are examined.

Speech-in-Noise Perception Deficit in Adults with Dyslexia: Effects of Background Type and Listening Configuration

ERIC Educational Resources Information Center

Dole, Marjorie; Hoen, Michel; Meunier, Fanny

2012-01-01

Developmental dyslexia is associated with impaired speech-in-noise perception. The goal of the present research was to further characterize this deficit in dyslexic adults. In order to specify the mechanisms and processing strategies used by adults with dyslexia during speech-in-noise perception, we explored the influence of background type,…

40 CFR 201.23 - Test site, weather conditions and background noise criteria for measurement at a 30 meter (100...

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 26 2013-07-01 2013-07-01 false Test site, weather conditions and background noise criteria for measurement at a 30 meter (100 feet) distance of the noise from locomotive and... TRANSPORTATION EQUIPMENT; INTERSTATE RAIL CARRIERS Measurement Criteria § 201.23 Test site, weather conditions...

40 CFR 201.23 - Test site, weather conditions and background noise criteria for measurement at a 30 meter (100...

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 25 2011-07-01 2011-07-01 false Test site, weather conditions and background noise criteria for measurement at a 30 meter (100 feet) distance of the noise from locomotive and... TRANSPORTATION EQUIPMENT; INTERSTATE RAIL CARRIERS Measurement Criteria § 201.23 Test site, weather conditions...

40 CFR 201.23 - Test site, weather conditions and background noise criteria for measurement at a 30 meter (100...

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 26 2012-07-01 2011-07-01 true Test site, weather conditions and background noise criteria for measurement at a 30 meter (100 feet) distance of the noise from locomotive and... TRANSPORTATION EQUIPMENT; INTERSTATE RAIL CARRIERS Measurement Criteria § 201.23 Test site, weather conditions...

40 CFR 201.23 - Test site, weather conditions and background noise criteria for measurement at a 30 meter (100...

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 25 2014-07-01 2014-07-01 false Test site, weather conditions and background noise criteria for measurement at a 30 meter (100 feet) distance of the noise from locomotive and... TRANSPORTATION EQUIPMENT; INTERSTATE RAIL CARRIERS Measurement Criteria § 201.23 Test site, weather conditions...

Modality of fear cues affects acoustic startle potentiation but not heart-rate response in patients with dental phobia

PubMed Central

Wannemüller, André; Sartory, Gudrun; Elsesser, Karin; Lohrmann, Thomas; Jöhren, Hans P.

2015-01-01

The acoustic startle response (SR) has consistently been shown to be enhanced by fear-arousing cross-modal background stimuli in phobics. Intra-modal fear-potentiation of acoustic SR was rarely investigated and generated inconsistent results. The present study compared the acoustic SR to phobia-related sounds with that to phobia-related pictures in 104 dental phobic patients and 22 controls. Acoustic background stimuli were dental treatment noises and birdsong and visual stimuli were dental treatment and neutral control pictures. Background stimuli were presented for 4 s, randomly followed by the administration of the startle stimulus. In addition to SR, heart-rate (HR) was recorded throughout the trials. Irrespective of their content, background pictures elicited greater SR than noises in both groups with a trend for phobic participants to show startle potentiation to phobia-related pictures but not noises. Unlike controls, phobics showed HR acceleration to both dental pictures and noises. HR acceleration of the phobia group was significantly positively correlated with SR in the noise condition only. The acoustic SR to phobia-related noises is likely to be inhibited by prolonged sensorimotor gating. PMID:25774142

The impact of different background noises: effects on cognitive performance and perceived disturbance in employees with aided hearing impairment and normal hearing.

PubMed

Hua, Håkan; Emilsson, Magnus; Kähäri, Kim; Widén, Stephen; Möller, Claes; Lyxell, Björn

2014-10-01

Health care professionals frequently meet employees with hearing impairment (HI) who experience difficulties at work. There are indications that the majority of these difficulties might be related to the presence of background noise. Moreover, research has also shown that high-level noise has a more detrimental effect on cognitive performance and self-rated disturbance in individuals with HI than low-level noise. The purpose of this study was to examine the impact of different types of background noise on cognitive performance and perceived disturbance (PD) in employees with aided HI and normal hearing. A mixed factorial design was conducted to examine the effect of noise in four experimental conditions. A total of 40 participants (21 men and 19 women) were recruited to take part in the study. The study sample consisted of employees with HI (n = 20) and normal hearing (n = 20). The group with HI had a mild-moderate sensorineural HI, and they were all frequent hearing-aid users. The current study was conducted by using four general work-related tasks (mental arithmetic, orthographic decoding, phonological decoding, and serial recall) in four different background conditions: (1) quiet, (2) office noise at 56 dBA, (3) daycare noise at 73.5 dBA, and (4) traffic noise at 72.5 dBA. Reaction time and the proportion of correct answers in the working tasks were used as outcome measures of cognitive performance. The Borg CR-10 scale was used to assess PD. Data collection occurred on two separate sessions, completed within 4 wk of each other. All tasks and experimental conditions were used in a counterbalanced order. Two-way analysis of variance with repeated measures was performed to analyze the results. To examine interaction effects, pairwise t-tests were used. Pearson correlation coefficients between reaction time and proportion of correct answers, and cognitive performance and PD were also calculated to examine the possible correlation between the different variables. No significant between-group or within-group differences in cognitive performance were observed across the four background conditions. Ratings of PD showed that both groups rated PD according to noise level, where higher noise level generated a higher PD. The present findings also demonstrated that the group with HI was more disturbed by higher than lower levels of noise (i.e., traffic and daycare setting compared with office setting). This pattern was observed consistently throughout four working tasks where the group with HI reported a significantly greater PD in the daycare and traffic settings compared with office noise. The present results demonstrate that background noise does not impair cognitive performance in nonauditory tasks in employees with HI and normal hearing, but that PD is affected to a greater extent in employees with HI during higher levels of background noise exposure. In addition, this study also supports previous studies regarding the detrimental effects that high-level noise has on employees with HI. Therefore, we emphasize the need of both self-rated and cognitive measurements in hearing care and occupational health services for both employees with normal hearing and HI. American Academy of Audiology.

Comparison of user volume control settings for portable music players with three earphone configurations in quiet and noisy environments.

PubMed

Henry, Paula; Foots, Ashley

2012-03-01

Listening to music is one of the most common forms of recreational noise exposure. Previous investigators have demonstrated that maximum output levels from headphones can exceed safe levels. Although preferred listening levels (PLL) in quiet environments may be at acceptable levels, the addition of background noise will add to the overall noise exposure of a listener. Use of listening devices that block out some of the background noise would potentially allow listeners to select lower PLLs for their music. Although one solution is in-the-ear earphones, an alternative solution is the use of earmuffs in conjunction with earbuds. There were two objectives to this experiment. The first was to determine if an alternative to in-the-ear earphones for noise attenuation (the addition of earmuffs to earbuds) would allow for lower PLLs through a portable media player (PMP) than earbuds. The second was to determine if a surrounding background noise would yield different PLLs than a directional noise source. This was an experimental study. Twenty-four adults with normal hearing. PLLs were measured for three earphone configurations in three listening conditions. The earphone configurations included earbuds, canal earphones, and earbuds in combination with hearing protection devices (HPDs). The listening conditions included quiet, noise from one loudspeaker, and noise from four surrounding loudspeakers. Participants listened in each noise and earphone combination for as long as they needed to determine their PLL for that condition. Once the participant determined their PLL, investigators made a 5 sec recording of the music through a probe tube microphone. The average PLLs in each noise and earphone combination were used as the dependent variable. Ear canal level PLLs were converted to free-field equivalents to compare to noise exposure standards and previously published data. The average PLL as measured in the ear canal was 74 dBA in the quiet conditions and 84 dBA in the noise conditions. Paired comparisons of the PLL in the presence of background noise for each pair of earphone configurations indicated significant differences for each comparison. An inverse relationship was observed between attenuation and PLL whereby the greater the attenuation, the lower the PLL. A comparison of the single noise source condition versus the surrounding noise condition did not result in a significant effect. The present work suggests that earphones that take advantage of noise attenuation can reduce the level at which listeners set music in the presence of background noise. An alternative to in-the-ear earphones for noise attenuation is the addition of earmuffs to earbuds. American Academy of Audiology.

The Rb 780-nanometer Faraday anomalous dispersion optical filter: Theory and experiment

NASA Technical Reports Server (NTRS)

Yin, B.; Alvarez, L. S.; Shay, T. M.

1994-01-01

The Faraday anomalous dispersion optical filter may provide ultra-high background noise rejection for free-space laser communications systems. The theoretical model for the filter is reported. The experimental measurements and their comparison with theoretical results are discussed. The results show that the filter can provide a 56-dB solar background noise rejection with about a 2-GHz transmission bandwidth and no image degradation. To further increase the background noise rejection, a composite Zeeman and Faraday anomalous dispersion optical filter is designed and experimentally demonstrated.

Technical noise supplement : TeNS : a technical supplement to the Traffic Noise Analysis Protocol.

DOT National Transportation Integrated Search

1998-10-01

The purpose of this Technical Noise Supplement (TeNS) is to provide technical background : information on transportation-related noise in general and highway traffic noise in : particular. It is designed to elaborate on technical concepts and procedu...

The Effects of Background Noise on Dichotic Listening to Consonant-Vowel Syllables

ERIC Educational Resources Information Center

Sequeira, Sarah Dos Santos; Specht, Karsten; Hamalainen, Heikki; Hugdahl, Kenneth

2008-01-01

Lateralization of verbal processing is frequently studied with the dichotic listening technique, yielding a so called right ear advantage (REA) to consonant-vowel (CV) syllables. However, little is known about how background noise affects the REA. To address this issue, we presented CV-syllables either in silence or with traffic background noise…

Effect of Energy Equalization on the Intelligibility of Speech in Fluctuating Background Interference for Listeners With Hearing Impairment

PubMed Central

D’Aquila, Laura A.; Desloge, Joseph G.; Braida, Louis D.

2017-01-01

The masking release (MR; i.e., better speech recognition in fluctuating compared with continuous noise backgrounds) that is evident for listeners with normal hearing (NH) is generally reduced or absent for listeners with sensorineural hearing impairment (HI). In this study, a real-time signal-processing technique was developed to improve MR in listeners with HI and offer insight into the mechanisms influencing the size of MR. This technique compares short-term and long-term estimates of energy, increases the level of short-term segments whose energy is below the average energy, and normalizes the overall energy of the processed signal to be equivalent to that of the original long-term estimate. This signal-processing algorithm was used to create two types of energy-equalized (EEQ) signals: EEQ1, which operated on the wideband speech plus noise signal, and EEQ4, which operated independently on each of four bands with equal logarithmic width. Consonant identification was tested in backgrounds of continuous and various types of fluctuating speech-shaped Gaussian noise including those with both regularly and irregularly spaced temporal fluctuations. Listeners with HI achieved similar scores for EEQ and the original (unprocessed) stimuli in continuous-noise backgrounds, while superior performance was obtained for the EEQ signals in fluctuating background noises that had regular temporal gaps but not for those with irregularly spaced fluctuations. Thus, in noise backgrounds with regularly spaced temporal fluctuations, the energy-normalized signals led to larger values of MR and higher intelligibility than obtained with unprocessed signals. PMID:28602128

Effects of noise and reverberation on speech perception and listening comprehension of children and adults in a classroom-like setting.

PubMed

Klatte, Maria; Lachmann, Thomas; Meis, Markus

2010-01-01

The effects of classroom noise and background speech on speech perception, measured by word-to-picture matching, and listening comprehension, measured by execution of oral instructions, were assessed in first- and third-grade children and adults in a classroom-like setting. For speech perception, in addition to noise, reverberation time (RT) was varied by conducting the experiment in two virtual classrooms with mean RT = 0.47 versus RT = 1.1 s. Children were more impaired than adults by background sounds in both speech perception and listening comprehension. Classroom noise evoked a reliable disruption in children's speech perception even under conditions of short reverberation. RT had no effect on speech perception in silence, but evoked a severe increase in the impairments due to background sounds in all age groups. For listening comprehension, impairments due to background sounds were found in the children, stronger for first- than for third-graders, whereas adults were unaffected. Compared to classroom noise, background speech had a smaller effect on speech perception, but a stronger effect on listening comprehension, remaining significant when speech perception was controlled. This indicates that background speech affects higher-order cognitive processes involved in children's comprehension. Children's ratings of the sound-induced disturbance were low overall and uncorrelated to the actual disruption, indicating that the children did not consciously realize the detrimental effects. The present results confirm earlier findings on the substantial impact of noise and reverberation on children's speech perception, and extend these to classroom-like environmental settings and listening demands closely resembling those faced by children at school.

Effect of temporal and spectral noise features on gap detection behavior by calling green treefrogs.

PubMed

Höbel, Gerlinde

2014-10-01

Communication plays a central role in the behavioral ecology of many animals, yet the background noise generated by large breeding aggregations may impair effective communication. A common behavioral strategy to ameliorate noise interference is gap detection, where signalers display primarily during lulls in the background noise. When attempting gap detection, signalers have to deal with the fact that the spacing and duration of silent gaps is often unpredictable, and that noise varies in its spectral composition and may thus vary in the degree in which it impacts communication. I conducted playback experiments to examine how male treefrogs deal with the problem that refraining from calling while waiting for a gap to appear limits a male's ability to attract females, yet producing calls during noise also interferes with effective sexual communication. I found that the temporal structure of noise (i.e., duration of noise and silent gap segments) had a stronger effect on male calling behavior than the spectral composition. Males placed calls predominantly during silent gaps and avoided call production during short, but not long, noise segments. This suggests that male treefrogs use a calling strategy that maximizes the production of calls without interference, yet allows for calling to persist if lulls in the background noise are infrequent. Copyright © 2014 Elsevier B.V. All rights reserved.

Speech-in-noise perception deficit in adults with dyslexia: effects of background type and listening configuration.

PubMed

Dole, Marjorie; Hoen, Michel; Meunier, Fanny

2012-06-01

Developmental dyslexia is associated with impaired speech-in-noise perception. The goal of the present research was to further characterize this deficit in dyslexic adults. In order to specify the mechanisms and processing strategies used by adults with dyslexia during speech-in-noise perception, we explored the influence of background type, presenting single target-words against backgrounds made of cocktail party sounds, modulated speech-derived noise or stationary noise. We also evaluated the effect of three listening configurations differing in terms of the amount of spatial processing required. In a monaural condition, signal and noise were presented to the same ear while in a dichotic situation, target and concurrent sound were presented to two different ears, finally in a spatialised configuration, target and competing signals were presented as if they originated from slightly differing positions in the auditory scene. Our results confirm the presence of a speech-in-noise perception deficit in dyslexic adults, in particular when the competing signal is also speech, and when both signals are presented to the same ear, an observation potentially relating to phonological accounts of dyslexia. However, adult dyslexics demonstrated better levels of spatial release of masking than normal reading controls when the background was speech, suggesting that they are well able to rely on denoising strategies based on spatial auditory scene analysis strategies. Copyright © 2012 Elsevier Ltd. All rights reserved.

49 CFR Appendix E to Part 227 - Use of Insert Earphones for Audiometric Testing

Code of Federal Regulations, 2011 CFR

2011-10-01

... audiometer. IV. Background Noise Levels Testing shall be conducted in a room where the background ambient noise octave-band sound pressures levels meet appendix D to this part. V. Conversion From Supra Aural...

The association of noise sensitivity with music listening, training, and aptitude.

PubMed

Kliuchko, Marina; Heinonen-Guzejev, Marja; Monacis, Lucia; Gold, Benjamin P; Heikkilä, Kauko V; Spinosa, Vittoria; Tervaniemi, Mari; Brattico, Elvira

2015-01-01

After intensive, long-term musical training, the auditory system of a musician is specifically tuned to perceive musical sounds. We wished to find out whether a musician's auditory system also develops increased sensitivity to any sound of everyday life, experiencing them as noise. For this purpose, an online survey, including questionnaires on noise sensitivity, musical background, and listening tests for assessing musical aptitude, was administered to 197 participants in Finland and Italy. Subjective noise sensitivity (assessed with the Weinstein's Noise Sensitivity Scale) was analyzed for associations with musicianship, musical aptitude, weekly time spent listening to music, and the importance of music in each person's life (or music importance). Subjects were divided into three groups according to their musical expertise: Nonmusicians (N = 103), amateur musicians (N = 44), and professional musicians (N = 50). The results showed that noise sensitivity did not depend on musical expertise or performance on musicality tests or the amount of active (attentive) listening to music. In contrast, it was associated with daily passive listening to music, so that individuals with higher noise sensitivity spent less time in passive (background) listening to music than those with lower sensitivity to noise. Furthermore, noise-sensitive respondents rated music as less important in their life than did individuals with lower sensitivity to noise. The results demonstrate that the special sensitivity of the auditory system derived from musical training does not lead to increased irritability from unwanted sounds. However, the disposition to tolerate contingent musical backgrounds in everyday life depends on the individual's noise sensitivity.

Note: innovative demodulation scheme for coherent detectors in cosmic microwave background experiments.

PubMed

Ishidoshiro, K; Chinone, Y; Hasegawa, M; Hazumi, M; Nagai, M; Tajima, O

2012-05-01

We propose an innovative demodulation scheme for coherent detectors used in cosmic microwave background polarization experiments. Removal of non-white noise, e.g., narrow-band noise, in detectors is one of the key requirements for the experiments. A combination of modulation and demodulation is used to extract polarization signals as well as to suppress such noise. Traditional demodulation, which is based on the two-point numerical differentiation, works as a first-order high pass filter for the noise. The proposed demodulation is based on the three-point numerical differentiation. It works as a second-order high pass filter. By using a real detector, we confirmed significant improvements of suppression power for the narrow-band noise. We also found improvement of the noise floor.

Faraday anomalous dispersion optical filters

NASA Technical Reports Server (NTRS)

Shay, T. M.; Yin, B.; Alvarez, L. S.

1993-01-01

The effect of Faraday anomalous dispersion optical filters on infrared and blue transitions of some alkali atoms is calculated. A composite system is designed to further increase the background noise rejection. The measured results of the solar background rejection and image quality through the filter are presented. The results show that the filter may provide high transmission and high background noise rejection with excellent image quality.

Left Superior Temporal Gyrus Is Coupled to Attended Speech in a Cocktail-Party Auditory Scene.

PubMed

Vander Ghinst, Marc; Bourguignon, Mathieu; Op de Beeck, Marc; Wens, Vincent; Marty, Brice; Hassid, Sergio; Choufani, Georges; Jousmäki, Veikko; Hari, Riitta; Van Bogaert, Patrick; Goldman, Serge; De Tiège, Xavier

2016-02-03

Using a continuous listening task, we evaluated the coupling between the listener's cortical activity and the temporal envelopes of different sounds in a multitalker auditory scene using magnetoencephalography and corticovocal coherence analysis. Neuromagnetic signals were recorded from 20 right-handed healthy adult humans who listened to five different recorded stories (attended speech streams), one without any multitalker background (No noise) and four mixed with a "cocktail party" multitalker background noise at four signal-to-noise ratios (5, 0, -5, and -10 dB) to produce speech-in-noise mixtures, here referred to as Global scene. Coherence analysis revealed that the modulations of the attended speech stream, presented without multitalker background, were coupled at ∼0.5 Hz to the activity of both superior temporal gyri, whereas the modulations at 4-8 Hz were coupled to the activity of the right supratemporal auditory cortex. In cocktail party conditions, with the multitalker background noise, the coupling was at both frequencies stronger for the attended speech stream than for the unattended Multitalker background. The coupling strengths decreased as the Multitalker background increased. During the cocktail party conditions, the ∼0.5 Hz coupling became left-hemisphere dominant, compared with bilateral coupling without the multitalker background, whereas the 4-8 Hz coupling remained right-hemisphere lateralized in both conditions. The brain activity was not coupled to the multitalker background or to its individual talkers. The results highlight the key role of listener's left superior temporal gyri in extracting the slow ∼0.5 Hz modulations, likely reflecting the attended speech stream within a multitalker auditory scene. When people listen to one person in a "cocktail party," their auditory cortex mainly follows the attended speech stream rather than the entire auditory scene. However, how the brain extracts the attended speech stream from the whole auditory scene and how increasing background noise corrupts this process is still debated. In this magnetoencephalography study, subjects had to attend a speech stream with or without multitalker background noise. Results argue for frequency-dependent cortical tracking mechanisms for the attended speech stream. The left superior temporal gyrus tracked the ∼0.5 Hz modulations of the attended speech stream only when the speech was embedded in multitalker background, whereas the right supratemporal auditory cortex tracked 4-8 Hz modulations during both noiseless and cocktail-party conditions. Copyright © 2016 the authors 0270-6474/16/361597-11$15.00/0.

Background Registration-Based Adaptive Noise Filtering of LWIR/MWIR Imaging Sensors for UAV Applications

PubMed Central

Kim, Byeong Hak; Kim, Min Young; Chae, You Seong

2017-01-01

Unmanned aerial vehicles (UAVs) are equipped with optical systems including an infrared (IR) camera such as electro-optical IR (EO/IR), target acquisition and designation sights (TADS), or forward looking IR (FLIR). However, images obtained from IR cameras are subject to noise such as dead pixels, lines, and fixed pattern noise. Nonuniformity correction (NUC) is a widely employed method to reduce noise in IR images, but it has limitations in removing noise that occurs during operation. Methods have been proposed to overcome the limitations of the NUC method, such as two-point correction (TPC) and scene-based NUC (SBNUC). However, these methods still suffer from unfixed pattern noise. In this paper, a background registration-based adaptive noise filtering (BRANF) method is proposed to overcome the limitations of conventional methods. The proposed BRANF method utilizes background registration processing and robust principle component analysis (RPCA). In addition, image quality verification methods are proposed that can measure the noise filtering performance quantitatively without ground truth images. Experiments were performed for performance verification with middle wave infrared (MWIR) and long wave infrared (LWIR) images obtained from practical military optical systems. As a result, it is found that the image quality improvement rate of BRANF is 30% higher than that of conventional NUC. PMID:29280970

Background Registration-Based Adaptive Noise Filtering of LWIR/MWIR Imaging Sensors for UAV Applications.

PubMed

Kim, Byeong Hak; Kim, Min Young; Chae, You Seong

2017-12-27

Unmanned aerial vehicles (UAVs) are equipped with optical systems including an infrared (IR) camera such as electro-optical IR (EO/IR), target acquisition and designation sights (TADS), or forward looking IR (FLIR). However, images obtained from IR cameras are subject to noise such as dead pixels, lines, and fixed pattern noise. Nonuniformity correction (NUC) is a widely employed method to reduce noise in IR images, but it has limitations in removing noise that occurs during operation. Methods have been proposed to overcome the limitations of the NUC method, such as two-point correction (TPC) and scene-based NUC (SBNUC). However, these methods still suffer from unfixed pattern noise. In this paper, a background registration-based adaptive noise filtering (BRANF) method is proposed to overcome the limitations of conventional methods. The proposed BRANF method utilizes background registration processing and robust principle component analysis (RPCA). In addition, image quality verification methods are proposed that can measure the noise filtering performance quantitatively without ground truth images. Experiments were performed for performance verification with middle wave infrared (MWIR) and long wave infrared (LWIR) images obtained from practical military optical systems. As a result, it is found that the image quality improvement rate of BRANF is 30% higher than that of conventional NUC.

Speech privacy and annoyance considerations in the acoustic environment of passenger cars of high-speed trains.

PubMed

Jeon, Jin Yong; Hong, Joo Young; Jang, Hyung Suk; Kim, Jae Hyeon

2015-12-01

It is necessary to consider not only annoyance of interior noises but also speech privacy to achieve acoustic comfort in a passenger car of a high-speed train because speech from other passengers can be annoying. This study aimed to explore an optimal acoustic environment to satisfy speech privacy and reduce annoyance in a passenger car. Two experiments were conducted using speech sources and compartment noise of a high speed train with varying speech-to-noise ratios (SNRA) and background noise levels (BNL). Speech intelligibility was tested in experiment I, and in experiment II, perceived speech privacy, annoyance, and acoustic comfort of combined sounds with speech and background noise were assessed. The results show that speech privacy and annoyance were significantly influenced by the SNRA. In particular, the acoustic comfort was evaluated as acceptable when the SNRA was less than -6 dB for both speech privacy and noise annoyance. In addition, annoyance increased significantly as the BNL exceeded 63 dBA, whereas the effect of the background-noise level on the speech privacy was not significant. These findings suggest that an optimal level of interior noise in a passenger car might exist between 59 and 63 dBA, taking normal speech levels into account.

Visualization of tire vibration and sound radiation and modeling of tire vibration with an emphasis on wave propagation

DOT National Transportation Integrated Search

2003-08-01

It is now known that tire/road interaction noise is the major contributor to exterior automobile noise and establishes the background noise level in many environments. Thus, the reduction of tire/road noise is a major environmental noise issue today....

Effects of noise on speech recognition: Challenges for communication by service members.

PubMed

Le Prell, Colleen G; Clavier, Odile H

2017-06-01

Speech communication often takes place in noisy environments; this is an urgent issue for military personnel who must communicate in high-noise environments. The effects of noise on speech recognition vary significantly according to the sources of noise, the number and types of talkers, and the listener's hearing ability. In this review, speech communication is first described as it relates to current standards of hearing assessment for military and civilian populations. The next section categorizes types of noise (also called maskers) according to their temporal characteristics (steady or fluctuating) and perceptive effects (energetic or informational masking). Next, speech recognition difficulties experienced by listeners with hearing loss and by older listeners are summarized, and questions on the possible causes of speech-in-noise difficulty are discussed, including recent suggestions of "hidden hearing loss". The final section describes tests used by military and civilian researchers, audiologists, and hearing technicians to assess performance of an individual in recognizing speech in background noise, as well as metrics that predict performance based on a listener and background noise profile. This article provides readers with an overview of the challenges associated with speech communication in noisy backgrounds, as well as its assessment and potential impact on functional performance, and provides guidance for important new research directions relevant not only to military personnel, but also to employees who work in high noise environments. Copyright © 2016 Elsevier B.V. All rights reserved.

Application of Smoothing Techniques for Tracking Maneuvering Targets. Multiple Target Tracking in Clutter: New Approaches

DTIC Science & Technology

1992-07-01

target state estimation is affected not only by the measurement noise but also by the uncertainty in the origins of the measurements. To improve the...to identify targets in the presence of anticipated background noise (including earth, lunar, star backgrounds, complicated spacecraft structures...each other. Futhermore, those frames are often degraded versions of the original scene due to blur and noise . Through the task of image registration

Track Score Processing of Multiple Dissimilar Sensors

DTIC Science & Technology

2007-06-01

sensors ( infrared and light detection and ranging system) and one radio frenquency sensor (radar). The signal to noise ratio and design considerations...categorized as Johnson noise , shot noise , generation-recombination noise , temperature noise , microphonic noise , 1/f noise , and finally electronic...of 2.1 µm. The values of detectivity in this figure were derived from an analysis of commercial detectors , under background- limited conditions, at

Accuracy of cochlear implant recipients in speech reception in the presence of background music.

PubMed

Gfeller, Kate; Turner, Christopher; Oleson, Jacob; Kliethermes, Stephanie; Driscoll, Virginia

2012-12-01

This study examined speech recognition abilities of cochlear implant (CI) recipients in the spectrally complex listening condition of 3 contrasting types of background music, and compared performance based upon listener groups: CI recipients using conventional long-electrode devices, Hybrid CI recipients (acoustic plus electric stimulation), and normal-hearing adults. We tested 154 long-electrode CI recipients using varied devices and strategies, 21 Hybrid CI recipients, and 49 normal-hearing adults on closed-set recognition of spondees presented in 3 contrasting forms of background music (piano solo, large symphony orchestra, vocal solo with small combo accompaniment) in an adaptive test. Signal-to-noise ratio thresholds for speech in music were examined in relation to measures of speech recognition in background noise and multitalker babble, pitch perception, and music experience. The signal-to-noise ratio thresholds for speech in music varied as a function of category of background music, group membership (long-electrode, Hybrid, normal-hearing), and age. The thresholds for speech in background music were significantly correlated with measures of pitch perception and thresholds for speech in background noise; auditory status was an important predictor. Evidence suggests that speech reception thresholds in background music change as a function of listener age (with more advanced age being detrimental), structural characteristics of different types of music, and hearing status (residual hearing). These findings have implications for everyday listening conditions such as communicating in social or commercial situations in which there is background music.

The association of noise sensitivity with music listening, training, and aptitude

PubMed Central

Kliuchko, Marina; Heinonen-Guzejev, Marja; Monacis, Lucia; Gold, Benjamin P.; Heikkilä, Kauko V.; Spinosa, Vittoria; Tervaniemi, Mari; Brattico, Elvira

2015-01-01

After intensive, long-term musical training, the auditory system of a musician is specifically tuned to perceive musical sounds. We wished to find out whether a musician's auditory system also develops increased sensitivity to any sound of everyday life, experiencing them as noise. For this purpose, an online survey, including questionnaires on noise sensitivity, musical background, and listening tests for assessing musical aptitude, was administered to 197 participants in Finland and Italy. Subjective noise sensitivity (assessed with the Weinstein's Noise Sensitivity Scale) was analyzed for associations with musicianship, musical aptitude, weekly time spent listening to music, and the importance of music in each person's life (or music importance). Subjects were divided into three groups according to their musical expertise: Nonmusicians (N = 103), amateur musicians (N = 44), and professional musicians (N = 50). The results showed that noise sensitivity did not depend on musical expertise or performance on musicality tests or the amount of active (attentive) listening to music. In contrast, it was associated with daily passive listening to music, so that individuals with higher noise sensitivity spent less time in passive (background) listening to music than those with lower sensitivity to noise. Furthermore, noise-sensitive respondents rated music as less important in their life than did individuals with lower sensitivity to noise. The results demonstrate that the special sensitivity of the auditory system derived from musical training does not lead to increased irritability from unwanted sounds. However, the disposition to tolerate contingent musical backgrounds in everyday life depends on the individual's noise sensitivity. PMID:26356378

Influence of Background Noise Produced in University Facilities on the Brain Waves Associated With Attention of Students and Employees.

PubMed

Trista N-Hernández, E; Pav On-García, I; Campos-Cantón, I; Ontaño N-García, L J; Kolosovas-Machuca, E S

2017-09-01

As a consequence of noise exposure, lack of attention badly affects directly the academic and work performance. The study of the brain and the waves that it produces is the most objective way to evaluate this process. Attentional improvement is associated with increases of the amplitude in both beta and theta bands. The objective of this work is to study the influence of background noise produced inside university facilities on changes in the cerebral waves related to attention processes (beta 13-30 Hz and theta 4-7 Hz). Volunteers were asked to perform a specific task in which attention was involved. This task was performed in both silent and noisy conditions. To evaluate the cerebral activity of volunteers during the development of the test, measurement of spontaneous activity (electroencephalogram) was developed. The results show significant decreases in both beta and theta frequency bands under background noise exposure. Since attentional improvement is related to an increment on amplitude of both beta and theta bands, it is suggested that decreases on amplitude of these frequency bands could directly be related to a lack of attention caused by the exposure to background noise.

Preconditioner-free Wiener filtering with a dense noise matrix

NASA Astrophysics Data System (ADS)

Huffenberger, Kevin M.

2018-05-01

This work extends the Elsner & Wandelt (2013) iterative method for efficient, preconditioner-free Wiener filtering to cases in which the noise covariance matrix is dense, but can be decomposed into a sum whose parts are sparse in convenient bases. The new method, which uses multiple messenger fields, reproduces Wiener-filter solutions for test problems, and we apply it to a case beyond the reach of the Elsner & Wandelt (2013) method. We compute the Wiener-filter solution for a simulated Cosmic Microwave Background (CMB) map that contains spatially varying, uncorrelated noise, isotropic 1/f noise, and large-scale horizontal stripes (like those caused by atmospheric noise). We discuss simple extensions that can filter contaminated modes or inverse-noise-filter the data. These techniques help to address complications in the noise properties of maps from current and future generations of ground-based Microwave Background experiments, like Advanced ACTPol, Simons Observatory, and CMB-S4.

Effect of environmental noise and music on dexmedetomidine-induced sedation in dogs

PubMed Central

Seddighi, Reza M.; Ng, Zenithson; Sun, Xiaocun; Rezac, DJ

2017-01-01

Background Previous studies in human patients suggest depth of sedation may be affected by environmental noise or music; however, related data in domestic animals is limited. The objective of the current study was to investigate the effect of noise and music on dexmedetomidine-induced (DM- 10 µg/kg, IM) sedation in 10 dogs. Methods In a crossover design, post-DM injection dogs were immediately subjected to recorded human voices at either 55–60 decibel (dB) (Noise 1) or 80–85 dB (Noise 2); classical music at 45–50 dB (Music); or background noise of 40–45 dB (Control+). Control− included IM saline injection and exposure to 40–45 dB background noise. Sedation was assessed via monitoring spontaneous behavior and accelerometry (delta-g) throughout three 20-min evaluation periods: baseline, noise exposure, and post-treatment. Sedation was further assessed during two restraint tests at 30 min (R1) and 40 min (R2) post-injection. A mixed model for crossover design was used to determine the effect of noise exposure and time on either spontaneous behavior scores or delta-g. The restraint scores were analyzed using a two-way repeated measures ANOVA. Results Spontaneous behavior scores indicated less sedation during Noise 2 compared to Control+ (P = 0.05). R2 restraint scores for all DM treatments except Noise 2 indicated significantly higher sedation than Control− [C+ (P = 0.003), M (P = 0.014) and N1 (P = 0.044)]. Discussion Results suggest that the quality of sedation is negatively impacted by high-intensity noise conditions (80–85 dB), but exposure to music did not improve sedation in this population of research dogs. PMID:28785527

NASA Langley Low Speed Aeroacoustic Wind Tunnel: Background Noise and Flow Survey Results Prior to FY05 Construction of Facilities Modifications

NASA Technical Reports Server (NTRS)

Booth, Earl R., Jr.; Henderson, Brenda S.

2005-01-01

The NASA Langley Research Center Low Speed Aeroacoustic Wind Tunnel is a premier facility for model-scale testing of jet noise reduction concepts at realistic flow conditions. However, flow inside the open jet test section is less than optimum. A Construction of Facilities project, scheduled for FY 05, will replace the flow collector with a new design intended to reduce recirculation in the open jet test section. The reduction of recirculation will reduce background noise levels measured by a microphone array impinged by the recirculation flow and will improve flow characteristics in the open jet tunnel flow. In order to assess the degree to which this modification is successful, background noise levels and tunnel flow are documented, in order to establish a baseline, in this report.

A refined methodology for modeling volume quantification performance in CT

NASA Astrophysics Data System (ADS)

Chen, Baiyu; Wilson, Joshua; Samei, Ehsan

2014-03-01

The utility of CT lung nodule volume quantification technique depends on the precision of the quantification. To enable the evaluation of quantification precision, we previously developed a mathematical model that related precision to image resolution and noise properties in uniform backgrounds in terms of an estimability index (e'). The e' was shown to predict empirical precision across 54 imaging and reconstruction protocols, but with different correlation qualities for FBP and iterative reconstruction (IR) due to the non-linearity of IR impacted by anatomical structure. To better account for the non-linearity of IR, this study aimed to refine the noise characterization of the model in the presence of textured backgrounds. Repeated scans of an anthropomorphic lung phantom were acquired. Subtracted images were used to measure the image quantum noise, which was then used to adjust the noise component of the e' calculation measured from a uniform region. In addition to the model refinement, the validation of the model was further extended to 2 nodule sizes (5 and 10 mm) and 2 segmentation algorithms. Results showed that the magnitude of IR's quantum noise was significantly higher in structured backgrounds than in uniform backgrounds (ASiR, 30-50%; MBIR, 100-200%). With the refined model, the correlation between e' values and empirical precision no longer depended on reconstruction algorithm. In conclusion, the model with refined noise characterization relfected the nonlinearity of iterative reconstruction in structured background, and further showed successful prediction of quantification precision across a variety of nodule sizes, dose levels, slice thickness, reconstruction algorithms, and segmentation software.

A generalised background correction algorithm for a Halo Doppler lidar and its application to data from Finland

DOE PAGES

Manninen, Antti J.; O'Connor, Ewan J.; Vakkari, Ville; ...

2016-03-03

Current commercially available Doppler lidars provide an economical and robust solution for measuring vertical and horizontal wind velocities, together with the ability to provide co- and cross-polarised backscatter profiles. The high temporal resolution of these instruments allows turbulent properties to be obtained from studying the variation in radial velocities. However, the instrument specifications mean that certain characteristics, especially the background noise behaviour, become a limiting factor for the instrument sensitivity in regions where the aerosol load is low. Turbulent calculations require an accurate estimate of the contribution from velocity uncertainty estimates, which are directly related to the signal-to-noise ratio. Anymore » bias in the signal-to-noise ratio will propagate through as a bias in turbulent properties. In this paper we present a method to correct for artefacts in the background noise behaviour of commercially available Doppler lidars and reduce the signal-to-noise ratio threshold used to discriminate between noise, and cloud or aerosol signals. We show that, for Doppler lidars operating continuously at a number of locations in Finland, the data availability can be increased by as much as 50 % after performing this background correction and subsequent reduction in the threshold. Furthermore the reduction in bias also greatly improves subsequent calculations of turbulent properties in weak signal regimes.« less

A generalised background correction algorithm for a Halo Doppler lidar and its application to data from Finland

DOE Office of Scientific and Technical Information (OSTI.GOV)

Manninen, Antti J.; O'Connor, Ewan J.; Vakkari, Ville

Current commercially available Doppler lidars provide an economical and robust solution for measuring vertical and horizontal wind velocities, together with the ability to provide co- and cross-polarised backscatter profiles. The high temporal resolution of these instruments allows turbulent properties to be obtained from studying the variation in radial velocities. However, the instrument specifications mean that certain characteristics, especially the background noise behaviour, become a limiting factor for the instrument sensitivity in regions where the aerosol load is low. Turbulent calculations require an accurate estimate of the contribution from velocity uncertainty estimates, which are directly related to the signal-to-noise ratio. Anymore » bias in the signal-to-noise ratio will propagate through as a bias in turbulent properties. In this paper we present a method to correct for artefacts in the background noise behaviour of commercially available Doppler lidars and reduce the signal-to-noise ratio threshold used to discriminate between noise, and cloud or aerosol signals. We show that, for Doppler lidars operating continuously at a number of locations in Finland, the data availability can be increased by as much as 50 % after performing this background correction and subsequent reduction in the threshold. Furthermore the reduction in bias also greatly improves subsequent calculations of turbulent properties in weak signal regimes.« less

Speech understanding in background noise with the two-microphone adaptive beamformer BEAM in the Nucleus Freedom Cochlear Implant System.

PubMed

Spriet, Ann; Van Deun, Lieselot; Eftaxiadis, Kyriaky; Laneau, Johan; Moonen, Marc; van Dijk, Bas; van Wieringen, Astrid; Wouters, Jan

2007-02-01

This paper evaluates the benefit of the two-microphone adaptive beamformer BEAM in the Nucleus Freedom cochlear implant (CI) system for speech understanding in background noise by CI users. A double-blind evaluation of the two-microphone adaptive beamformer BEAM and a hardware directional microphone was carried out with five adult Nucleus CI users. The test procedure consisted of a pre- and post-test in the lab and a 2-wk trial period at home. In the pre- and post-test, the speech reception threshold (SRT) with sentences and the percentage correct phoneme scores for CVC words were measured in quiet and background noise at different signal-to-noise ratios. Performance was assessed for two different noise configurations (with a single noise source and with three noise sources) and two different noise materials (stationary speech-weighted noise and multitalker babble). During the 2-wk trial period at home, the CI users evaluated the noise reduction performance in different listening conditions by means of the SSQ questionnaire. In addition to the perceptual evaluation, the noise reduction performance of the beamformer was measured physically as a function of the direction of the noise source. Significant improvements of both the SRT in noise (average improvement of 5-16 dB) and the percentage correct phoneme scores (average improvement of 10-41%) were observed with BEAM compared to the standard hardware directional microphone. In addition, the SSQ questionnaire and subjective evaluation in controlled and real-life scenarios suggested a possible preference for the beamformer in noisy environments. The evaluation demonstrates that the adaptive noise reduction algorithm BEAM in the Nucleus Freedom CI-system may significantly increase the speech perception by cochlear implantees in noisy listening conditions. This is the first monolateral (adaptive) noise reduction strategy actually implemented in a mainstream commercial CI.

Monte Carlo simulation for background study of geophysical inspection with cosmic-ray muons

NASA Astrophysics Data System (ADS)

Nishiyama, Ryuichi; Taketa, Akimichi; Miyamoto, Seigo; Kasahara, Katsuaki

2016-08-01

Several attempts have been made to obtain a radiographic image inside volcanoes using cosmic-ray muons (muography). Muography is expected to resolve highly heterogeneous density profiles near the surface of volcanoes. However, several prior works have failed to make clear observations due to contamination by background noise. The background contamination leads to an overestimation of the muon flux and consequently a significant underestimation of the density in the target mountains. To investigate the origin of the background noise, we performed a Monte Carlo simulation. The main components of the background noise in muography are found to be low-energy protons, electrons and muons in case of detectors without particle identification and with energy thresholds below 1 GeV. This result was confirmed by comparisons with actual observations of nuclear emulsions. This result will be useful for detector design in future works, and in addition some previous works of muography should be reviewed from the view point of background contamination.

Background Noise Characteristics in the Western Part of Romania

NASA Astrophysics Data System (ADS)

Grecu, B.; Neagoe, C.; Tataru, D.; Stuart, G.

2012-04-01

The seismological database of the western part of Romania increased significantly during the last years, when 33 broadband seismic stations provided by SEIS-UK (10 CMG 40 T's - 30 s, 9 CMG 3T's - 120 s, 14 CMG 6T's - 30 s) were deployed in the western part of the country in July 2009 to operate autonomously for two years. These stations were installed within a joint project (South Carpathian Project - SCP) between University of Leeds, UK and National Institute for Earth Physics (NIEP), Romania that aimed at determining the lithospheric structure and geodynamical evolution of the South Carpathian Orogen. The characteristics of the background seismic noise recorded at the SCP broadband seismic network have been studied in order to identify the variations in background seismic noise as a function of time of day, season, and particular conditions at the stations. Power spectral densities (PSDs) and their corresponding probability density functions (PDFs) are used to characterize the background seismic noise. At high frequencies (> 1 Hz), seismic noise seems to have cultural origin, since notable variations between daytime and nighttime noise levels are observed at most of the stations. The seasonal variations are seen in the microseisms band. The noise levels increase during the winter and autumn months and decrease in summer and spring seasons, while the double-frequency peak shifts from lower periods in summer to longer periods in winter. The analysis of the probability density functions for stations located in different geologic conditions points out that the noise level is higher for stations sited on softer formations than those sited on hard rocks. Finally, the polarization analysis indicates that the main sources of secondary microseisms are found in the Mediterranean Sea and Atlantic Ocean.

Distance Measurement Error in Time-of-Flight Sensors Due to Shot Noise

PubMed Central

Illade-Quinteiro, Julio; Brea, Víctor M.; López, Paula; Cabello, Diego; Doménech-Asensi, Gines

2015-01-01

Unlike other noise sources, which can be reduced or eliminated by different signal processing techniques, shot noise is an ever-present noise component in any imaging system. In this paper, we present an in-depth study of the impact of shot noise on time-of-flight sensors in terms of the error introduced in the distance estimation. The paper addresses the effect of parameters, such as the size of the photosensor, the background and signal power or the integration time, and the resulting design trade-offs. The study is demonstrated with different numerical examples, which show that, in general, the phase shift determination technique with two background measurements approach is the most suitable for pixel arrays of large resolution. PMID:25723141

Sources, paths, and concepts for reduction of noise in the test section of the NASA Langley 4x7m wind tunnel

NASA Technical Reports Server (NTRS)

Hayden, R. E.; Wilby, J. F.

1984-01-01

NASA is investigating the feasibility of modifying the 4x7m Wind Tunnel at the Langley Research Center to make it suitable for a variety of aeroacoustic testing applications, most notably model helicopter rotors. The amount of noise reduction required to meet NASA's goal for test section background noise was determined, the predominant sources and paths causing the background noise were quantified, and trade-off studies between schemes to reduce fan noise at the source and those to attenuate the sound generated in the circuit between the sources and the test section were carried out. An extensive data base is also presented on circuit sources and paths.

49 CFR Appendix E to Part 227 - Use of Insert Earphones for Audiometric Testing

Code of Federal Regulations, 2010 CFR

2010-10-01

... RAILROAD ADMINISTRATION, DEPARTMENT OF TRANSPORTATION OCCUPATIONAL NOISE EXPOSURE Pt. 227, App. E Appendix.... B. Technicians who conduct audiometric tests must be trained to insert the earphones correctly into... audiometer. IV. Background Noise Levels Testing shall be conducted in a room where the background ambient...

Hearing through the noise: Biologically inspired noise reduction

NASA Astrophysics Data System (ADS)

Lee, Tyler Paul

Vocal communication in the natural world demands that a listener perform a remarkably complicated task in real-time. Vocalizations mix with all other sounds in the environment as they travel to the listener, arriving as a jumbled low-dimensional signal. A listener must then use this signal to extract the structure corresponding to individual sound sources. How this computation is implemented in the brain remains poorly understood, yet an accurate description of such mechanisms would impact a variety of medical and technological applications of sound processing. In this thesis, I describe initial work on how neurons in the secondary auditory cortex of the Zebra Finch extract song from naturalistic background noise. I then build on our understanding of the function of these neurons by creating an algorithm that extracts speech from natural background noise using spectrotemporal modulations. The algorithm, implemented as an artificial neural network, can be flexibly applied to any class of signal or noise and performs better than an optimal frequency-based noise reduction algorithm for a variety of background noises and signal-to-noise ratios. One potential drawback to using spectrotemporal modulations for noise reduction, though, is that analyzing the modulations present in an ongoing sound requires a latency set by the slowest temporal modulation computed. The algorithm avoids this problem by reducing noise predictively, taking advantage of the large amount of temporal structure present in natural sounds. This predictive denoising has ties to recent work suggesting that the auditory system uses attention to focus on predicted regions of spectrotemporal space when performing auditory scene analysis.

Prewhitening of Colored Noise Fields for Detection of Threshold Sources

DTIC Science & Technology

1993-11-07

determines the noise covariance matrix, prewhitening techniques allow detection of threshold sources. The multiple signal classification ( MUSIC ...SUBJECT TERMS 1S. NUMBER OF PAGES AR Model, Colored Noise Field, Mixed Spectra Model, MUSIC , Noise Field, 52 Prewhitening, SNR, Standardized Test...EXAMPLE 2: COMPLEX AR COEFFICIENT .............................................. 5 EXAMPLE 3: MUSIC IN A COLORED BACKGROUND NOISE ...................... 6

Binaural speech discrimination under noise in hearing-impaired listeners.

PubMed

Kumar, K V; Rao, A B

1988-10-01

This study was undertaken to assess speech discrimination under binaural listening with background noise in hearing-impaired subjects. Subjects (58 sensori-neural, 23 conductive, and 19 mixed) were administered an indigenous version of W-22 PB words under: Condition I--Quiet--chamber noise below 28 dB with speech at 60 dB; and at a constant signal-to-noise (S/N) ratio of +10 dB with background white noise at 70 dB in Condition II and 80 dB in Condition III. The scores were a) 81 +/- 16%, b) 77 +/- 9%, and c) 79 +/- 13%. Mean scores decreased significantly (p less than 0.001) with noise in all groups while the score was more (p less than 0.001) at the higher noise level only in the sensori-neural group. The decrease in scores with advancing hearing impairment was less in noise than in quiet, probably due to binaural and satisfactory S/N ratio. The scores did not fall below 70% unless the handicap was marked. The need for suitable standards of binaural speech discrimination under noise in aircrew assessment is emphasized.

Multiple wavelength spectral system simulating background light noise environment in satellite laser communications

NASA Astrophysics Data System (ADS)

Lu, Wei; Sun, Jianfeng; Hou, Peipei; Xu, Qian; Xi, Yueli; Zhou, Yu; Zhu, Funan; Liu, Liren

2017-08-01

Performance of satellite laser communications between GEO and LEO satellites can be influenced by background light noise appeared in the field of view due to sunlight or planets and some comets. Such influences should be studied on the ground testing platform before the space application. In this paper, we introduce a simulator that can simulate the real case of background light noise in space environment during the data talking via laser beam between two lonely satellites. This simulator can not only simulate the effect of multi-wavelength spectrum, but also the effects of adjustable angles of field-of-view, large range of adjustable optical power and adjustable deflection speeds of light noise in space environment. We integrate these functions into a device with small and compact size for easily mobile use. Software control function is also achieved via personal computer to adjust these functions arbitrarily. Keywords:

Comparison of the signal-to-noise characteristics of quantum versus thermal ghost imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

O'Sullivan, Malcolm N.; Chan, Kam Wai Clifford; Boyd, Robert W.

2010-11-15

We present a theoretical comparison of the signal-to-noise characteristics of quantum versus thermal ghost imaging. We first calculate the signal-to-noise ratio of each process in terms of its controllable experimental conditions. We show that a key distinction is that a thermal ghost image always resides on top of a large background; the fluctuations in this background constitutes an intrinsic noise source for thermal ghost imaging. In contrast, there is a negligible intrinsic background to a quantum ghost image. However, for practical reasons involving achievable illumination levels, acquisition times for thermal ghost images are often much shorter than those for quantummore » ghost images. We provide quantitative predictions for the conditions under which each process provides superior performance. Our conclusion is that each process can provide useful functionality, although under complementary conditions.« less

Listen to the Noise: Noise Is Beneficial for Cognitive Performance in ADHD

ERIC Educational Resources Information Center

Soderlund, Goran; Sikstrom, Sverker; Smart, Andrew

2007-01-01

Background: Noise is typically conceived of as being detrimental to cognitive performance. However, given the mechanism of stochastic resonance, a certain amount of noise can benefit performance. We investigate cognitive performance in noisy environments in relation to a neurocomputational model of attention deficit hyperactivity disorder (ADHD)…

Auditory-neurophysiological responses to speech during early childhood: Effects of background noise

PubMed Central

White-Schwoch, Travis; Davies, Evan C.; Thompson, Elaine C.; Carr, Kali Woodruff; Nicol, Trent; Bradlow, Ann R.; Kraus, Nina

2015-01-01

Early childhood is a critical period of auditory learning, during which children are constantly mapping sounds to meaning. But learning rarely occurs under ideal listening conditions—children are forced to listen against a relentless din. This background noise degrades the neural coding of these critical sounds, in turn interfering with auditory learning. Despite the importance of robust and reliable auditory processing during early childhood, little is known about the neurophysiology underlying speech processing in children so young. To better understand the physiological constraints these adverse listening scenarios impose on speech sound coding during early childhood, auditory-neurophysiological responses were elicited to a consonant-vowel syllable in quiet and background noise in a cohort of typically-developing preschoolers (ages 3–5 yr). Overall, responses were degraded in noise: they were smaller, less stable across trials, slower, and there was poorer coding of spectral content and the temporal envelope. These effects were exacerbated in response to the consonant transition relative to the vowel, suggesting that the neural coding of spectrotemporally-dynamic speech features is more tenuous in noise than the coding of static features—even in children this young. Neural coding of speech temporal fine structure, however, was more resilient to the addition of background noise than coding of temporal envelope information. Taken together, these results demonstrate that noise places a neurophysiological constraint on speech processing during early childhood by causing a breakdown in neural processing of speech acoustics. These results may explain why some listeners have inordinate difficulties understanding speech in noise. Speech-elicited auditory-neurophysiological responses offer objective insight into listening skills during early childhood by reflecting the integrity of neural coding in quiet and noise; this paper documents typical response properties in this age group. These normative metrics may be useful clinically to evaluate auditory processing difficulties during early childhood. PMID:26113025

Patterns of Song across Natural and Anthropogenic Soundscapes Suggest That White-Crowned Sparrows Minimize Acoustic Masking and Maximize Signal Content.

PubMed

Derryberry, Elizabeth P; Danner, Raymond M; Danner, Julie E; Derryberry, Graham E; Phillips, Jennifer N; Lipshutz, Sara E; Gentry, Katherine; Luther, David A

2016-01-01

Soundscapes pose both evolutionarily recent and long-standing sources of selection on acoustic communication. We currently know more about the impact of evolutionarily recent human-generated noise on communication than we do about how natural sounds such as pounding surf have shaped communication signals over evolutionary time. Based on signal detection theory, we hypothesized that acoustic phenotypes will vary with both anthropogenic and natural background noise levels and that similar mechanisms of cultural evolution and/or behavioral flexibility may underlie this variation. We studied song characteristics of white-crowned sparrows (Zonotrichia leucophrys nuttalli) across a noise gradient that includes both anthropogenic and natural sources of noise in San Francisco and Marin counties, California, USA. Both anthropogenic and natural soundscapes contain high amplitude low frequency noise (traffic or surf, respectively), so we predicted that birds would produce songs with higher minimum frequencies in areas with higher amplitude background noise to avoid auditory masking. We also anticipated that song minimum frequencies would be higher than the projected lower frequency limit of hearing based on site-specific masking profiles. Background noise was a strong predictor of song minimum frequency, both within a local noise gradient of three urban sites with the same song dialect and cultural evolutionary history, and across the regional noise gradient, which encompasses 11 urban and rural sites, several dialects, and several anthropogenic and natural sources of noise. Among rural sites alone, background noise tended to predict song minimum frequency, indicating that urban sites were not solely responsible for driving the regional pattern. These findings support the hypothesis that songs vary with local and regional soundscapes regardless of the source of noise. Song minimum frequency from five core study sites was also higher than the lower frequency limit of hearing at each site, further supporting the hypothesis that songs vary to transmit through noise in local soundscapes. Minimum frequencies leveled off at noisier sites, suggesting that minimum frequencies are constrained to an upper limit, possibly to retain the information content of wider bandwidths. We found evidence that site noise was a better predictor of song minimum frequency than territory noise in both anthropogenic and natural soundscapes, suggesting that cultural evolution rather than immediate behavioral flexibility is responsible for local song variation. Taken together, these results indicate that soundscapes shape song phenotype across both evolutionarily recent and long-standing soundscapes.

Patterns of Song across Natural and Anthropogenic Soundscapes Suggest That White-Crowned Sparrows Minimize Acoustic Masking and Maximize Signal Content

PubMed Central

Derryberry, Graham E.; Phillips, Jennifer N.; Lipshutz, Sara E.; Gentry, Katherine; Luther, David A.

2016-01-01

Soundscapes pose both evolutionarily recent and long-standing sources of selection on acoustic communication. We currently know more about the impact of evolutionarily recent human-generated noise on communication than we do about how natural sounds such as pounding surf have shaped communication signals over evolutionary time. Based on signal detection theory, we hypothesized that acoustic phenotypes will vary with both anthropogenic and natural background noise levels and that similar mechanisms of cultural evolution and/or behavioral flexibility may underlie this variation. We studied song characteristics of white-crowned sparrows (Zonotrichia leucophrys nuttalli) across a noise gradient that includes both anthropogenic and natural sources of noise in San Francisco and Marin counties, California, USA. Both anthropogenic and natural soundscapes contain high amplitude low frequency noise (traffic or surf, respectively), so we predicted that birds would produce songs with higher minimum frequencies in areas with higher amplitude background noise to avoid auditory masking. We also anticipated that song minimum frequencies would be higher than the projected lower frequency limit of hearing based on site-specific masking profiles. Background noise was a strong predictor of song minimum frequency, both within a local noise gradient of three urban sites with the same song dialect and cultural evolutionary history, and across the regional noise gradient, which encompasses 11 urban and rural sites, several dialects, and several anthropogenic and natural sources of noise. Among rural sites alone, background noise tended to predict song minimum frequency, indicating that urban sites were not solely responsible for driving the regional pattern. These findings support the hypothesis that songs vary with local and regional soundscapes regardless of the source of noise. Song minimum frequency from five core study sites was also higher than the lower frequency limit of hearing at each site, further supporting the hypothesis that songs vary to transmit through noise in local soundscapes. Minimum frequencies leveled off at noisier sites, suggesting that minimum frequencies are constrained to an upper limit, possibly to retain the information content of wider bandwidths. We found evidence that site noise was a better predictor of song minimum frequency than territory noise in both anthropogenic and natural soundscapes, suggesting that cultural evolution rather than immediate behavioral flexibility is responsible for local song variation. Taken together, these results indicate that soundscapes shape song phenotype across both evolutionarily recent and long-standing soundscapes. PMID:27128443

46 CFR 113.50-15 - Loudspeakers.

Code of Federal Regulations, 2011 CFR

2011-10-01

.... With the vessel underway in normal conditions, the minimum sound pressure levels for broadcasting emergency announcements must be— (1) In interior spaces, 75 dB(A) or, if the background noise level exceeds 75 dB(A), then at least 20 dB(A) above maximum background noise level; and (2) In exterior spaces, 80...

Effects of noise and working memory capacity on memory processing of speech for hearing-aid users.

PubMed

Ng, Elaine Hoi Ning; Rudner, Mary; Lunner, Thomas; Pedersen, Michael Syskind; Rönnberg, Jerker

2013-07-01

It has been shown that noise reduction algorithms can reduce the negative effects of noise on memory processing in persons with normal hearing. The objective of the present study was to investigate whether a similar effect can be obtained for persons with hearing impairment and whether such an effect is dependent on individual differences in working memory capacity. A sentence-final word identification and recall (SWIR) test was conducted in two noise backgrounds with and without noise reduction as well as in quiet. Working memory capacity was measured using a reading span (RS) test. Twenty-six experienced hearing-aid users with moderate to moderately severe sensorineural hearing loss. Noise impaired recall performance. Competing speech disrupted memory performance more than speech-shaped noise. For late list items the disruptive effect of the competing speech background was virtually cancelled out by noise reduction for persons with high working memory capacity. Noise reduction can reduce the adverse effect of noise on memory for speech for persons with good working memory capacity. We argue that the mechanism behind this is faster word identification that enhances encoding into working memory.

Guide to the evaluation of human exposure to noise from large wind turbines

NASA Technical Reports Server (NTRS)

Stephens, D. G.; Shepherd, K. P.; Hubbard, H. H.; Grosveld, F.

1982-01-01

Guidance for evaluating human exposure to wind turbine noise is provided and includes consideration of the source characteristics, the propagation to the receiver location, and the exposure of the receiver to the noise. The criteria for evaluation of human exposure are based on comparisons of the noise at the receiver location with the human perception thresholds for wind turbine noise and noise-induced building vibrations in the presence of background noise.

Noise propagation in urban and industrial areas

NASA Technical Reports Server (NTRS)

Davies, H. G.

1976-01-01

Noise propagation in streets and the discrepancies between theoretical analyses and field measurements are discussed. A cell-model is used to estimate the general background level of noise due to vehicular sources distributed over the urban area.

Controlling Low-Rate Signal Path Microdischarge for an Ultra-Low-Background Proportional Counter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mace, Emily K.; Aalseth, Craig E.; Bonicalzi, Ricco

2013-05-01

ABSTRACT Pacific Northwest National Laboratory (PNNL) has developed an ultra-low-background proportional counter (ULBPC) made of high purity copper. These detectors are part of an ultra-low-background counting system (ULBCS) in the newly constructed shallow underground laboratory at PNNL (at a depth of ~30 meters water-equivalent). To control backgrounds, the current preamplifier electronics are located outside the ULBCS shielding. Thus the signal from the detector travels through ~1 meter of cable and is potentially susceptible to high voltage microdischarge and other sources of electronic noise. Based on initial successful tests, commercial cables and connectors were used for this critical signal path. Subsequentmore » testing across different batches of commercial cables and connectors, however, showed unwanted (but still low) rates of microdischarge noise. To control this noise source, two approaches were pursued: first, to carefully validate cables, connectors, and other commercial components in this critical signal path, making modifications where necessary; second, to develop a custom low-noise, low-background preamplifier that can be integrated with the ULBPC and thus remove most commercial components from the critical signal path. This integrated preamplifier approach is based on the Amptek A250 low-noise charge-integrating preamplifier module. The initial microdischarge signals observed are presented and characterized according to the suspected source. Each of the approaches for mitigation is described, and the results from both are compared with each other and with the original performance seen with commercial cables and connectors.« less

Research on infrared dim-point target detection and tracking under sea-sky-line complex background

NASA Astrophysics Data System (ADS)

Dong, Yu-xing; Li, Yan; Zhang, Hai-bo

2011-08-01

Target detection and tracking technology in infrared image is an important part of modern military defense system. Infrared dim-point targets detection and recognition under complex background is a difficulty and important strategic value and challenging research topic. The main objects that carrier-borne infrared vigilance system detected are sea-skimming aircrafts and missiles. Due to the characteristics of wide field of view of vigilance system, the target is usually under the sea clutter. Detection and recognition of the target will be taken great difficulties .There are some traditional point target detection algorithms, such as adaptive background prediction detecting method. When background has dispersion-decreasing structure, the traditional target detection algorithms would be more useful. But when the background has large gray gradient, such as sea-sky-line, sea waves etc .The bigger false-alarm rate will be taken in these local area .It could not obtain satisfactory results. Because dim-point target itself does not have obvious geometry or texture feature ,in our opinion , from the perspective of mathematics, the detection of dim-point targets in image is about singular function analysis .And from the perspective image processing analysis , the judgment of isolated singularity in the image is key problem. The foregoing points for dim-point targets detection, its essence is a separation of target and background of different singularity characteristics .The image from infrared sensor usually accompanied by different kinds of noise. These external noises could be caused by the complicated background or from the sensor itself. The noise might affect target detection and tracking. Therefore, the purpose of the image preprocessing is to reduce the effects from noise, also to raise the SNR of image, and to increase the contrast of target and background. According to the low sea-skimming infrared flying small target characteristics , the median filter is used to eliminate noise, improve signal-to-noise ratio, then the multi-point multi-storey vertical Sobel algorithm will be used to detect the sea-sky-line ,so that we can segment sea and sky in the image. Finally using centroid tracking method to capture and trace target. This method has been successfully used to trace target under the sea-sky complex background.

Effects of ocular aberrations on contrast detection in noise.

PubMed

Liang, Bo; Liu, Rong; Dai, Yun; Zhou, Jiawei; Zhou, Yifeng; Zhang, Yudong

2012-08-06

We use adaptive optics (AO) techniques to manipulate the ocular aberrations and elucidate the effects of these ocular aberrations on contrast detection in a noisy background. The detectability of sine wave gratings at frequencies of 4, 8, and 16 circles per degree (cpd) was measured in a standard two-interval force-choice staircase procedure against backgrounds of various levels of white noise. The observer's ocular aberrations were either corrected with AO or left uncorrected. In low levels of external noise, contrast detection thresholds are always lowered by AO correction, whereas in high levels of external noise, they are generally elevated by AO correction. Higher levels of external noise are required to make this threshold elevation observable when signal spatial frequencies increase from 4 to 16 cpd. The linear-amplifier-model fit shows that mostly sampling efficiency and equivalent noise both decrease with AO correction. Our findings indicate that ocular aberrations could be beneficial for contrast detection in high-level noises. The implications of these findings are discussed.

Noise reduction in digital holography based on a filtering algorithm

NASA Astrophysics Data System (ADS)

Zhang, Wenhui; Cao, Liangcai; Zhang, Hua; Jin, Guofan; Brady, David

2018-02-01

Holography is a tool to record the object wavefront by interference. Complex amplitude of the object wave is coded into a two dimensional hologram. Unfortunately, the conjugate wave and background wave would also appear at the object plane during reconstruction, as noise, which blurs the reconstructed object. From the perspective of wave, we propose a filtering algorithm to get a noise-reduced reconstruction. Due to the fact that the hologram is a kind of amplitude grating, three waves would appear when reconstruction, which are object wave, conjugate wave and background wave. The background is easy to eliminate by frequency domain filtering. The object wave and conjugate wave are signals to be dealt with. These two waves, as a whole, propagate in the space. However, when detected at the original object plane, the object wave would diffract into a sparse pattern while the conjugate wave would diffract into a diffused pattern forming the noise. Hence, the noise can be reduced based on these difference with a filtering algorithm. Both amplitude and phase distributions are truthfully retrieved in our simulation and experimental demonstration.

Readout circuit with novel background suppression for long wavelength infrared focal plane arrays

NASA Astrophysics Data System (ADS)

Xie, L.; Xia, X. J.; Zhou, Y. F.; Wen, Y.; Sun, W. F.; Shi, L. X.

2011-02-01

In this article, a novel pixel readout circuit using a switched-capacitor integrator mode background suppression technique is presented for long wavelength infrared focal plane arrays. This circuit can improve dynamic range and signal-to-noise ratio by suppressing the large background current during integration. Compared with other background suppression techniques, the new background suppression technique is less sensitive to the process mismatch and has no additional shot noise. The proposed circuit is theoretically analysed and simulated while taking into account the non-ideal characteristics. The result shows that the background suppression non-uniformity is ultra-low even for a large process mismatch. The background suppression non-uniformity of the proposed circuit can also remain very small with technology scaling.

Lesion detection performance of cone beam CT images with anatomical background noise: single-slice vs. multi-slice human and model observer study

NASA Astrophysics Data System (ADS)

Han, Minah; Jang, Hanjoo; Baek, Jongduk

2018-03-01

We investigate lesion detectability and its trends for different noise structures in single-slice and multislice CBCT images with anatomical background noise. Anatomical background noise is modeled using a power law spectrum of breast anatomy. Spherical signal with a 2 mm diameter is used for modeling a lesion. CT projection data are acquired by the forward projection and reconstructed by the Feldkamp-Davis-Kress algorithm. To generate different noise structures, two types of reconstruction filters (Hanning and Ram-Lak weighted ramp filters) are used in the reconstruction, and the transverse and longitudinal planes of reconstructed volume are used for detectability evaluation. To evaluate single-slice images, the central slice, which contains the maximum signal energy, is used. To evaluate multislice images, central nine slices are used. Detectability is evaluated using human and model observer studies. For model observer, channelized Hotelling observer (CHO) with dense difference-of-Gaussian (D-DOG) channels are used. For all noise structures, detectability by a human observer is higher for multislice images than single-slice images, and the degree of detectability increase in multislice images depends on the noise structure. Variation in detectability for different noise structures is reduced in multislice images, but detectability trends are not much different between single-slice and multislice images. The CHO with D-DOG channels predicts detectability by a human observer well for both single-slice and multislice images.

Ambient seismic noise levels: A survey of the permanent and temporary seismographic networks in Morocco, North Africa

NASA Astrophysics Data System (ADS)

El Fellah, Y.; Khairy Abd Ed-Aal, A.; El Moudnib, L.; Mimoun, H.; Villasenor, A.; Gallart, J.; Thomas, C.; Elouai, D.; Mimoun, C.; Himmi, M.

2013-12-01

Abstract The results, of a conducted study carried out to analyze variations in ambient seismic noise levels at sites of the installed broadband stations in Morocco, North Africa, are obtained. The permanent and the temporary seismic stations installed in Morocco of the Scientific Institute ( IS, Rabat, Morocco), institute de Ciencias de la Tierra Jaume almera (ICTJA, Barcelona, Spain) and Institut für Geophysik (Munster, Germany) were used in this study. In this work, we used 23 broadband seismic stations installed in different structural domains covering all Morocco from south to north. The main purposes of the current study are: 1) to present a catalog of seismic background noise spectra for Morocco obtained from recently installed broadband stations, 2) to assess the effects of experimental temporary seismic vault construction, 3) to determine the time needed for noise at sites to stabilize, 4) to establish characteristics and origin of seismic noise at those sites. We calculated power spectral densities of background noise for each component of each broadband seismometer deployed in the different investigated sites and then compared them with the high-noise model and low-noise Model of Peterson (1993). All segments from day and night local time windows were included in the calculation without parsing out earthquakes. The obtained results of the current study could be used forthcoming to evaluate permanent station quality. Moreover, this study could be considered as a first step to develop new seismic noise models in North Africa not included in Peterson (1993). Keywords Background noise; Power spectral density; Model of Peterson; Scientific Institute; Institute de Ciencias de la Tierra Jaume almera; Institut für Geophysik

Learning to identify contrast-defined letters in peripheral vision

PubMed Central

Chung, Susana T.L.; Levi, Dennis M.; Li, Roger W.

2009-01-01

Performance for identifying luminance-defined letters in peripheral vision improves with training. The purpose of the present study was to examine whether performance for identifying contrast-defined letters also improves with training in peripheral vision, and whether any improvement transfers to luminance-defined letters. Eight observers were trained to identify contrast-defined letters presented singly at 10° eccentricity in the inferior visual field. Before and after training, we measured observers’ thresholds for identifying luminance-defined and contrast-defined letters, embedded within a field of white luminance noise (maximum luminance contrast = 0, 0.25, and 0.5), at the same eccentric location. Each training session consisted of 10 blocks (100 trials per block) of identifying contrast-defined letters at a background noise contrast of 0.5. Letters (x-height = 4.2°) were the 26 lowercase letters of the Times-Roman alphabet. Luminance-defined letters were generated by introducing a luminance difference between the stimulus letter and its mid-gray background. The background noise covered both the letter and its background. Contrast-defined letters were generated by introducing a differential noise contrast between the group of pixels that made up the stimulus letter and the group of pixels that made up the background. Following training, observers showed a significant reduction in threshold for identifying contrast-defined letters (p < 0.0001). Averaged across observers and background noise contrasts, the reduction was 25.8%, with the greatest reduction (32%) occurring at the trained background noise contrast. There was virtually no transfer of improvement to luminance-defined letters, or to an untrained letter size (2× original), or an untrained retinal location (10° superior field). In contrast, learning transferred completely to the untrained contralateral eye. Our results show that training improves performance for identifying contrast-defined letters in peripheral vision. This perceptual learning effect seems to be stimulus-specific, as it shows no transfer to the identification of luminance-defined letters. The complete interocular transfer, and the retinotopic (retinal location) and size specificity of the learning effect are consistent with the properties of neurons in early visual area V2. PMID:16337252

Contextual effects of noise on vocalization encoding in primary auditory cortex

PubMed Central

Ni, Ruiye; Bender, David A.; Shanechi, Amirali M.; Gamble, Jeffrey R.

2016-01-01

Robust auditory perception plays a pivotal function for processing behaviorally relevant sounds, particularly with distractions from the environment. The neuronal coding enabling this ability, however, is still not well understood. In this study, we recorded single-unit activity from the primary auditory cortex (A1) of awake marmoset monkeys (Callithrix jacchus) while delivering conspecific vocalizations degraded by two different background noises: broadband white noise and vocalization babble. Noise effects on neural representation of target vocalizations were quantified by measuring the responses' similarity to those elicited by natural vocalizations as a function of signal-to-noise ratio. A clustering approach was used to describe the range of response profiles by reducing the population responses to a summary of four response classes (robust, balanced, insensitive, and brittle) under both noise conditions. This clustering approach revealed that, on average, approximately two-thirds of the neurons change their response class when encountering different noises. Therefore, the distortion induced by one particular masking background in single-unit responses is not necessarily predictable from that induced by another, suggesting the low likelihood of a unique group of noise-invariant neurons across different background conditions in A1. Regarding noise influence on neural activities, the brittle response group showed addition of spiking activity both within and between phrases of vocalizations relative to clean vocalizations, whereas the other groups generally showed spiking activity suppression within phrases, and the alteration between phrases was noise dependent. Overall, the variable single-unit responses, yet consistent response types, imply that primate A1 performs scene analysis through the collective activity of multiple neurons. NEW & NOTEWORTHY The understanding of where and how auditory scene analysis is accomplished is of broad interest to neuroscientists. In this paper, we systematically investigated neuronal coding of multiple vocalizations degraded by two distinct noises at various signal-to-noise ratios in nonhuman primates. In the process, we uncovered heterogeneity of single-unit representations for different auditory scenes yet homogeneity of responses across the population. PMID:27881720

The impact of road traffic noise on cognitive performance in attention-based tasks depends on noise level even within moderate-level ranges

PubMed Central

Schlittmeier, Sabine J.; Feil, Alexandra; Liebl, Andreas; Hellbrück, Jürgen

2015-01-01

Little empirical evidence is available regarding the effects of road traffic noise on cognitive performance in adults, although traffic noise can be heard at many offices and home office workplaces. Our study tested the impact of road traffic noise at different levels (50 dB(A), 60 dB(A), 70 dB(A)) on performance in three tasks that differed with respect to their dependency on attentional and storage functions, as follows: The Stroop task, in which performance relied predominantly on attentional functions (e.g., inhibition of automated responses; Experiment 1: n = 24); a non-automated multistage mental arithmetic task calling for both attentional and storage functions (Exp. 2: n = 18); and verbal serial recall, which placed a burden predominantly on storage functions (Experiment 3: n = 18). Better performance was observed during moderate road traffic noise at 50 dB(A) compared to loud traffic noise at 70 dB(A) in attention-based tasks (Experiments 1-2). This contrasted with the effects of irrelevant speech (60 dB(A)), which was included in the experiments as a well-explored and common noise source in office settings. A disturbance impact of background speech was only given in the two tasks that called for storage functions (Experiments 2-3). In addition to the performance data, subjective annoyance ratings were collected. Consistent with the level effect of road traffic noise found in the performance data, a moderate road traffic noise at 50 dB(A) was perceived as significantly less annoying than a loud road traffic noise at 70 dB(A), which was found, however, independently of the task at hand. Furthermore, the background sound condition with the highest detrimental performance effect in a task was also rated as most annoying in this task, i.e., traffic noise at 70 dB(A) in the Stroop task, and background speech in the mental arithmetic and serial recall tasks. PMID:25913554

Contextual effects of noise on vocalization encoding in primary auditory cortex.

PubMed

Ni, Ruiye; Bender, David A; Shanechi, Amirali M; Gamble, Jeffrey R; Barbour, Dennis L

2017-02-01

Robust auditory perception plays a pivotal function for processing behaviorally relevant sounds, particularly with distractions from the environment. The neuronal coding enabling this ability, however, is still not well understood. In this study, we recorded single-unit activity from the primary auditory cortex (A1) of awake marmoset monkeys (Callithrix jacchus) while delivering conspecific vocalizations degraded by two different background noises: broadband white noise and vocalization babble. Noise effects on neural representation of target vocalizations were quantified by measuring the responses' similarity to those elicited by natural vocalizations as a function of signal-to-noise ratio. A clustering approach was used to describe the range of response profiles by reducing the population responses to a summary of four response classes (robust, balanced, insensitive, and brittle) under both noise conditions. This clustering approach revealed that, on average, approximately two-thirds of the neurons change their response class when encountering different noises. Therefore, the distortion induced by one particular masking background in single-unit responses is not necessarily predictable from that induced by another, suggesting the low likelihood of a unique group of noise-invariant neurons across different background conditions in A1. Regarding noise influence on neural activities, the brittle response group showed addition of spiking activity both within and between phrases of vocalizations relative to clean vocalizations, whereas the other groups generally showed spiking activity suppression within phrases, and the alteration between phrases was noise dependent. Overall, the variable single-unit responses, yet consistent response types, imply that primate A1 performs scene analysis through the collective activity of multiple neurons. The understanding of where and how auditory scene analysis is accomplished is of broad interest to neuroscientists. In this paper, we systematically investigated neuronal coding of multiple vocalizations degraded by two distinct noises at various signal-to-noise ratios in nonhuman primates. In the process, we uncovered heterogeneity of single-unit representations for different auditory scenes yet homogeneity of responses across the population. Copyright © 2017 the American Physiological Society.

The Impact of Age, Background Noise, Semantic Ambiguity, and Hearing Loss on Recognition Memory for Spoken Sentences

ERIC Educational Resources Information Center

Koeritzer, Margaret A.; Rogers, Chad S.; Van Engen, Kristin J.; Peelle, Jonathan E.

2018-01-01

Purpose: The goal of this study was to determine how background noise, linguistic properties of spoken sentences, and listener abilities (hearing sensitivity and verbal working memory) affect cognitive demand during auditory sentence comprehension. Method: We tested 30 young adults and 30 older adults. Participants heard lists of sentences in…

46 CFR 113.50-15 - Loudspeakers.

Code of Federal Regulations, 2010 CFR

2010-10-01

... loudspeakers must be watertight and suitably protected from the effects of the wind and seas. (c) There must be... emergency announcements must be— (1) In interior spaces, 75 dB(A) or, if the background noise level exceeds 75 dB(A), then at least 20 dB(A) above maximum background noise level; and (2) In exterior spaces, 80...

The Effect of Background Music and Background Noise on the Task Performance of Introverts and Extraverts

ERIC Educational Resources Information Center

Cassidy, Gianna; MacDonald, Raymond A. R.

2007-01-01

The study investigated the effects of music with high arousal potential and negative affect (HA), music with low arousal potential and positive affect (LA), and everyday noise, on the cognitive task performance of introverts and extraverts. Forty participants completed five cognitive tasks: immediate recall, free recall, numerical and delayed…

Joint Service Aircrew Mask (JSAM) - Tactical Aircraft (TA) A/P22P-14A Respirator Assembly (V)3: Noise Attenuation and Speech Intelligibility Performance with Double Hearing Protection, HGU-68/P Flight Helmet

DTIC Science & Technology

2017-03-31

dB Sound Pressure Level (SPL) background pink noise. The speech intelligibility tests shall result in a Modified Rhyme Test (MRT) score as listed...below. Speech intelligibility testing shall be measured per ANSI S3.2 for each background pink noise level using a minimum of ten talkers and of ten...listeners. The test shall be conducted wearing the JSAM-TA using appropriate communication amplification. Test must include the configurations

Low stimulus environments: reducing noise levels in continuing care.

PubMed

Brown, Juliette; Fawzi, Waleed; Shah, Amar; Joyce, Margaret; Holt, Genevieve; McCarthy, Cathy; Stevenson, Carmel; Marange, Rosca; Shakes, Joy; Solomon-Ayeh, Kwesi

2016-01-01

In the low stimulus environment project, we aimed to reduce the levels of intrusive background noise on an older adult mental health ward, combining a very straightforward measure on decibel levels with a downstream measure of reduced distress and agitation as expressed in incidents of violence. This project on reducing background noise levels on older adult wards stemmed from work the team had done on reducing levels of violence and aggression. We approached the problem using quality improvement methods. Reducing harm to patients and staff is a strategic aim of our Trust and in our efforts we were supported by the Trust's extensive programme of quality improvement, including training and support provided by the Institute for Healthcare Improvement and the trust's own Quality Improvement team. Prior to the project we were running a weekly multi-disciplinary quality improvement group on the ward. We established from this a sub-group to address the specific problem of noise levels and invited carers of people with dementia on our ward to the group. The project was led by nursing staff. We used a noise meter app readily downloadable from the internet to monitor background noise levels on the ward and establish a baseline measure. As a group we used a driver diagram to identify an overall aim and a clear understanding of the major factors that would drive improvements. We also used a staff and carer survey to identify further areas to work on. Change ideas that came from staff and carers included the use of the noise meter to track and report back on noise levels, the use of posters to remind staff about noise levels, the introduction of a visual indication of current noise levels (the Yacker Tracker), the addition of relaxing background music, and adaptations to furniture and environment. We tested many of these over the course of nine months in 2015, using the iterative learning gained from multiple PDSA cycles. The specific aim was a decrease from above 60dB to below 50dB in background noise on the wards. Following our interventions, we have managed to decrease noise levels on the ward to 53dB on average. The success of this project to date has relied on the involvement of ward staff and carers - those most affected by the problem - in generating workable local solutions. As many of the change ideas amounted to harm free interventions it was easier for us to make a case to test them out in the real-life setting. Nevertheless we were surprised at how effective such seemingly simple ideas have been in improving the environment on the ward. We have incorporated the change ideas into routine practice and are advising other wards on similar projects.

Cryocooled terahertz photoconductive detector system with background-limited performance in 1.5–4 THz frequency range

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aoki, Makoto; Hiromoto, Norihisa, E-mail: dnhirom@ipc.shizuoka.ac

2015-10-15

We describe a 4-K-cryocooled dual-band terahertz (THz) photoconductive detector system with background-limited performance. The detector system comprises two THz photoconductive detectors covering a response in a wide frequency range from 1.5 to 4 THz, low noise amplifiers, optical low-pass filters to eliminate input radiation of higher frequencies, and a mechanical 4 K Gifford-McMahon refrigerator that provides practical and convenient operation without a liquid He container. The electrical and optical performances of the THz detector system were evaluated at a detector temperature of 4 K under 300 K background radiation. We proved that the detector system can achieve background-limited noise-equivalent-power onmore » the order of 10{sup −14} W/Hz{sup 1/2} in the frequency range from 1.5 to 4 THz even if the vibration noise of the mechanical refrigerator is present.« less

A Low-Noise Germanium Ionization Spectrometer for Low-Background Science

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aalseth, Craig E.; Colaresi, Jim; Collar, Juan I.

2016-12-01

Recent progress on the development of very low energy threshold high purity germanium ionization spectrometers has produced an instrument of 1.2 kg mass and excellent noise performance. The detector was installed in a low-background cryostat intended for use in a low mass, WIMP dark matter direct detection search. The integrated detector and low background cryostat achieved noise performance of 98 eV full-width half-maximum of an input electronic pulse generator peak and gamma-ray energy resolution of 1.9 keV full-width half-maximum at the 60Co gamma-ray energy of 1332 keV. This Transaction reports the thermal characterization of the low-background cryostat, specifications of themore » newly prepared 1.2 kg p-type point contact germanium detector, and the ionization spectroscopy – energy resolution and energy threshold – performance of the integrated system.« less

Cryocooled terahertz photoconductive detector system with background-limited performance in 1.5-4 THz frequency range.

PubMed

Aoki, Makoto; Hiromoto, Norihisa

2015-10-01

We describe a 4-K-cryocooled dual-band terahertz (THz) photoconductive detector system with background-limited performance. The detector system comprises two THz photoconductive detectors covering a response in a wide frequency range from 1.5 to 4 THz, low noise amplifiers, optical low-pass filters to eliminate input radiation of higher frequencies, and a mechanical 4 K Gifford-McMahon refrigerator that provides practical and convenient operation without a liquid He container. The electrical and optical performances of the THz detector system were evaluated at a detector temperature of 4 K under 300 K background radiation. We proved that the detector system can achieve background-limited noise-equivalent-power on the order of 10(-14) W/Hz(1/2) in the frequency range from 1.5 to 4 THz even if the vibration noise of the mechanical refrigerator is present.

Low noise WDR ROIC for InGaAs SWIR image sensor

NASA Astrophysics Data System (ADS)

Ni, Yang

2017-11-01

Hybridized image sensors are actually the only solution for image sensing beyond the spectral response of silicon devices. By hybridization, we can combine the best sensing material and photo-detector design with high performance CMOS readout circuitry. In the infrared band, we are facing typically 2 configurations: high background situation and low background situation. The performance of high background sensors are conditioned mainly by the integration capacity in each pixel which is the case for mid-wave and long-wave infrared detectors. For low background situation, the detector's performance is mainly limited by the pixel's noise performance which is conditioned by dark signal and readout noise. In the case of reflection based imaging condition, the pixel's dynamic range is also an important parameter. This is the case for SWIR band imaging. We are particularly interested by InGaAs based SWIR image sensors.

Spectral and temporal changes to speech produced in the presence of energetic and informational maskers.

PubMed

Cooke, Martin; Lu, Youyi

2010-10-01

Talkers change the way they speak in noisy conditions. For energetic maskers, speech production changes are relatively well-understood, but less is known about how informational maskers such as competing speech affect speech production. The current study examines the effect of energetic and informational maskers on speech production by talkers speaking alone or in pairs. Talkers produced speech in quiet and in backgrounds of speech-shaped noise, speech-modulated noise, and competing speech. Relative to quiet, speech output level and fundamental frequency increased and spectral tilt flattened in proportion to the energetic masking capacity of the background. In response to modulated backgrounds, talkers were able to reduce substantially the degree of temporal overlap with the noise, with greater reduction for the competing speech background. Reduction in foreground-background overlap can be expected to lead to a release from both energetic and informational masking for listeners. Passive changes in speech rate, mean pause length or pause distribution cannot explain the overlap reduction, which appears instead to result from a purposeful process of listening while speaking. Talkers appear to monitor the background and exploit upcoming pauses, a strategy which is particularly effective for backgrounds containing intelligible speech.

ELLIPTICAL WEIGHTED HOLICs FOR WEAK LENSING SHEAR MEASUREMENT. III. THE EFFECT OF RANDOM COUNT NOISE ON IMAGE MOMENTS IN WEAK LENSING ANALYSIS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Okura, Yuki; Futamase, Toshifumi, E-mail: yuki.okura@nao.ac.jp, E-mail: tof@astr.tohoku.ac.jp

This is the third paper on the improvement of systematic errors in weak lensing analysis using an elliptical weight function, referred to as E-HOLICs. In previous papers, we succeeded in avoiding errors that depend on the ellipticity of the background image. In this paper, we investigate the systematic error that depends on the signal-to-noise ratio of the background image. We find that the origin of this error is the random count noise that comes from the Poisson noise of sky counts. The random count noise makes additional moments and centroid shift error, and those first-order effects are canceled in averaging,more » but the second-order effects are not canceled. We derive the formulae that correct this systematic error due to the random count noise in measuring the moments and ellipticity of the background image. The correction formulae obtained are expressed as combinations of complex moments of the image, and thus can correct the systematic errors caused by each object. We test their validity using a simulated image and find that the systematic error becomes less than 1% in the measured ellipticity for objects with an IMCAT significance threshold of {nu} {approx} 11.7.« less

Moon meteoritic seismic hum: Steady state prediction

USGS Publications Warehouse

Lognonne, P.; Feuvre, M.L.; Johnson, C.L.; Weber, R.C.

2009-01-01

We use three different statistical models describing the frequency of meteoroid impacts on Earth to estimate the seismic background noise due to impacts on the lunar surface. Because of diffraction, seismic events on the Moon are typically characterized by long codas, lasting 1 h or more. We find that the small but frequent impacts generate seismic signals whose codas overlap in time, resulting in a permanent seismic noise that we term the "lunar hum" by analogy with the Earth's continuous seismic background seismic hum. We find that the Apollo era impact detection rates and amplitudes are well explained by a model that parameterizes (1) the net seismic impulse due to the impactor and resulting ejecta and (2) the effects of diffraction and attenuation. The formulation permits the calculation of a composite waveform at any point on the Moon due to simulated impacts at any epicentral distance. The root-mean-square amplitude of this waveform yields a background noise level that is about 100 times lower than the resolution of the Apollo long-period seismometers. At 2 s periods, this noise level is more than 1000 times lower than the low noise model prediction for Earth's microseismic noise. Sufficiently sensitive seismometers will allow the future detection of several impacts per day at body wave frequencies. Copyright 2009 by the American Geophysical Union.

Musical Training during Early Childhood Enhances the Neural Encoding of Speech in Noise

ERIC Educational Resources Information Center

Strait, Dana L.; Parbery-Clark, Alexandra; Hittner, Emily; Kraus, Nina

2012-01-01

For children, learning often occurs in the presence of background noise. As such, there is growing desire to improve a child's access to a target signal in noise. Given adult musicians' perceptual and neural speech-in-noise enhancements, we asked whether similar effects are present in musically-trained children. We assessed the perception and…

Characterizing performance of ultra-sensitive accelerometers

NASA Technical Reports Server (NTRS)

Sebesta, Henry

1990-01-01

An overview is given of methodology and test results pertaining to the characterization of ultra sensitive accelerometers. Two issues are of primary concern. The terminology ultra sensitive accelerometer is used to imply instruments whose noise floors and resolution are at the state of the art. Hence, the typical approach of verifying an instrument's performance by measuring it with a yet higher quality instrument (or standard) is not practical. Secondly, it is difficult to find or create an environment with sufficiently low background acceleration. The typical laboratory acceleration levels will be at several orders of magnitude above the noise floor of the most sensitive accelerometers. Furthermore, this background must be treated as unknown since the best instrument available is the one to be tested. A test methodology was developed in which two or more like instruments are subjected to the same but unknown background acceleration. Appropriately selected spectral analysis techniques were used to separate the sensors' output spectra into coherent components and incoherent components. The coherent part corresponds to the background acceleration being measured by the sensors being tested. The incoherent part is attributed to sensor noise and data acquisition and processing noise. The method works well for estimating noise floors that are 40 to 50 dB below the motion applied to the test accelerometers. The accelerometers being tested are intended for use as feedback sensors in a system to actively stabilize an inertial guidance component test platform.

Child voice and noise: a pilot study of noise in day cares and the effects on 10 children's voice quality according to perceptual evaluation.

PubMed

McAllister, Anita M; Granqvist, Svante; Sjölander, Peta; Sundberg, Johan

2009-09-01

The purpose of this investigation was to study children's exposure to background noise at the ears during a normal day at the day care center and also to relate this to a perceptual evaluation of voice quality. Ten children, from three day care centers, with no history of hearing and speech problems or frequent infections were selected as subjects. A binaural recording technique was used with two microphones placed on both sides of the subject's head, at equal distance from the mouth. A portable digital audio tape (DAT) recorder (Sony TCD-D 100, Stockholm, Sweden) was attached to the subject's waist. Three recordings were made for each child during the day. Each recording was calibrated and started with three repetitions of three sentences containing only sonorants. The recording technique allowed separate analyses of the background noise level and of the sound pressure level (SPL) of each subjects' own voice. Results showed a mean background noise level for the three day care centers at 82.6dBA Leq, ranging from 81.5 to 83.6dBA Leq. Day care center no. 2 had the highest mean value and also the highest value at any separate recording session with a mean background noise level of 85.4dBA Leq during the noontime recordings. Perceptual evaluation showed that the children attending this day care center also received higher values on the following voice characteristics: hoarseness, breathiness, and hyperfunction. Girls increased their loudness level during the day, whereas for boys no such change could be observed.

Speech Understanding in Noise in Elderly Adults: The Effect of Inhibitory Control and Syntactic Complexity

ERIC Educational Resources Information Center

van Knijff, Eline C.; Coene, Martine; Govaerts, Paul J.

2018-01-01

Background: Previous research has suggested that speech perception in elderly adults is influenced not only by age-related hearing loss or presbycusis but also by declines in cognitive abilities, by background noise and by the syntactic complexity of the message. Aims: To gain further insight into the influence of these cognitive as well as…

Cortical processing of dynamic sound envelope transitions.

PubMed

Zhou, Yi; Wang, Xiaoqin

2010-12-08

Slow envelope fluctuations in the range of 2-20 Hz provide important segmental cues for processing communication sounds. For a successful segmentation, a neural processor must capture envelope features associated with the rise and fall of signal energy, a process that is often challenged by the interference of background noise. This study investigated the neural representations of slowly varying envelopes in quiet and in background noise in the primary auditory cortex (A1) of awake marmoset monkeys. We characterized envelope features based on the local average and rate of change of sound level in envelope waveforms and identified envelope features to which neurons were selective by reverse correlation. Our results showed that envelope feature selectivity of A1 neurons was correlated with the degree of nonmonotonicity in their static rate-level functions. Nonmonotonic neurons exhibited greater feature selectivity than monotonic neurons in quiet and in background noise. The diverse envelope feature selectivity decreased spike-timing correlation among A1 neurons in response to the same envelope waveforms. As a result, the variability, but not the average, of the ensemble responses of A1 neurons represented more faithfully the dynamic transitions in low-frequency sound envelopes both in quiet and in background noise.

Enhanced backgrounds in scene rendering with GTSIMS

NASA Astrophysics Data System (ADS)

Prussing, Keith F.; Pierson, Oliver; Cordell, Chris; Stewart, John; Nielson, Kevin

2018-05-01

A core component to modeling visible and infrared sensor responses is the ability to faithfully recreate background noise and clutter in a synthetic image. Most tracking and detection algorithms use a combination of signal to noise or clutter to noise ratios to determine if a signature is of interest. A primary source of clutter is the background that defines the environment in which a target is placed. Over the past few years, the Electro-Optical Systems Laboratory (EOSL) at the Georgia Tech Research Institute has made significant improvements to its in house simulation framework GTSIMS. First, we have expanded our terrain models to include the effects of terrain orientation on emission and reflection. Second, we have included the ability to model dynamic reflections with full BRDF support. Third, we have added the ability to render physically accurate cirrus clouds. And finally, we have updated the overall rendering procedure to reduce the time necessary to generate a single frame by taking advantage of hardware acceleration. Here, we present the updates to GTSIMS to better predict clutter and noise doe to non-uniform backgrounds. Specifically, we show how the addition of clouds, terrain, and improved non-uniform sky rendering improve our ability to represent clutter during scene generation.

Listeners Experience Linguistic Masking Release in Noise-Vocoded Speech-in-Speech Recognition.

PubMed

Viswanathan, Navin; Kokkinakis, Kostas; Williams, Brittany T

2018-02-15

The purpose of this study was to evaluate whether listeners with normal hearing perceiving noise-vocoded speech-in-speech demonstrate better intelligibility of target speech when the background speech was mismatched in language (linguistic release from masking [LRM]) and/or location (spatial release from masking [SRM]) relative to the target. We also assessed whether the spectral resolution of the noise-vocoded stimuli affected the presence of LRM and SRM under these conditions. In Experiment 1, a mixed factorial design was used to simultaneously manipulate the masker language (within-subject, English vs. Dutch), the simulated masker location (within-subject, right, center, left), and the spectral resolution (between-subjects, 6 vs. 12 channels) of noise-vocoded target-masker combinations presented at +25 dB signal-to-noise ratio (SNR). In Experiment 2, the study was repeated using a spectral resolution of 12 channels at +15 dB SNR. In both experiments, listeners' intelligibility of noise-vocoded targets was better when the background masker was Dutch, demonstrating reliable LRM in all conditions. The pattern of results in Experiment 1 was not reliably different across the 6- and 12-channel noise-vocoded speech. Finally, a reliable spatial benefit (SRM) was detected only in the more challenging SNR condition (Experiment 2). The current study is the first to report a clear LRM benefit in noise-vocoded speech-in-speech recognition. Our results indicate that this benefit is available even under spectrally degraded conditions and that it may augment the benefit due to spatial separation of target speech and competing backgrounds.

40 CFR 205.55-4 - Labeling-compliance.

Code of Federal Regulations, 2011 CFR

2011-07-01

... PROGRAMS TRANSPORTATION EQUIPMENT NOISE EMISSION CONTROLS Medium and Heavy Trucks § 205.55-4 Labeling... contrasts with the background of the label: (i) The label heading: Vehicle Noise Emission Control...) The statement: This Vehicle Conforms to U.S. EPA Regulations for Noise Emission Applicable to Medium...

An algorithm to improve speech recognition in noise for hearing-impaired listeners

PubMed Central

Healy, Eric W.; Yoho, Sarah E.; Wang, Yuxuan; Wang, DeLiang

2013-01-01

Despite considerable effort, monaural (single-microphone) algorithms capable of increasing the intelligibility of speech in noise have remained elusive. Successful development of such an algorithm is especially important for hearing-impaired (HI) listeners, given their particular difficulty in noisy backgrounds. In the current study, an algorithm based on binary masking was developed to separate speech from noise. Unlike the ideal binary mask, which requires prior knowledge of the premixed signals, the masks used to segregate speech from noise in the current study were estimated by training the algorithm on speech not used during testing. Sentences were mixed with speech-shaped noise and with babble at various signal-to-noise ratios (SNRs). Testing using normal-hearing and HI listeners indicated that intelligibility increased following processing in all conditions. These increases were larger for HI listeners, for the modulated background, and for the least-favorable SNRs. They were also often substantial, allowing several HI listeners to improve intelligibility from scores near zero to values above 70%. PMID:24116438

SVD and Hankel matrix based de-noising approach for ball bearing fault detection and its assessment using artificial faults

NASA Astrophysics Data System (ADS)

Golafshan, Reza; Yuce Sanliturk, Kenan

2016-03-01

Ball bearings remain one of the most crucial components in industrial machines and due to their critical role, it is of great importance to monitor their conditions under operation. However, due to the background noise in acquired signals, it is not always possible to identify probable faults. This incapability in identifying the faults makes the de-noising process one of the most essential steps in the field of Condition Monitoring (CM) and fault detection. In the present study, Singular Value Decomposition (SVD) and Hankel matrix based de-noising process is successfully applied to the ball bearing time domain vibration signals as well as to their spectrums for the elimination of the background noise and the improvement the reliability of the fault detection process. The test cases conducted using experimental as well as the simulated vibration signals demonstrate the effectiveness of the proposed de-noising approach for the ball bearing fault detection.

Updating working memory in aircraft noise and speech noise causes different fMRI activations

PubMed Central

Sætrevik, Bjørn; Sörqvist, Patrik

2015-01-01

The present study used fMRI/BOLD neuroimaging to investigate how visual-verbal working memory is updated when exposed to three different background-noise conditions: speech noise, aircraft noise and silence. The number-updating task that was used can distinguish between “substitution processes,” which involve adding new items to the working memory representation and suppressing old items, and “exclusion processes,” which involve rejecting new items and maintaining an intact memory set. The current findings supported the findings of a previous study by showing that substitution activated the dorsolateral prefrontal cortex, the posterior medial frontal cortex and the parietal lobes, whereas exclusion activated the anterior medial frontal cortex. Moreover, the prefrontal cortex was activated more by substitution processes when exposed to background speech than when exposed to aircraft noise. These results indicate that (a) the prefrontal cortex plays a special role when task-irrelevant materials should be denied access to working memory and (b) that, when compensating for different types of noise, either different cognitive mechanisms are involved or those cognitive mechanisms that are involved are involved to different degrees. PMID:25352319

The effects of ipsilateral, contralateral, and bilateral broadband noise on the mid-level hump in intensity discriminationa)

PubMed Central

Roverud, Elin; Strickland, Elizabeth A.

2015-01-01

Previous psychoacoustical and physiological studies indicate that the medial olivocochlear reflex (MOCR), a bilateral, sound-evoked reflex, may lead to improved sound intensity discrimination in background noise. The MOCR can decrease the range of basilar-membrane compression and can counteract effects of neural adaptation from background noise. However, the contribution of these processes to intensity discrimination is not well understood. This study examined the effect of ipsilateral, contralateral, and bilateral noise on the “mid-level hump.” The mid-level hump refers to intensity discrimination Weber fractions (WFs) measured for short-duration, high-frequency tones which are poorer at mid levels than at lower or higher levels. The mid-level hump WFs may reflect a limitation due to basilar-membrane compression, and thus may be decreased by the MOCR. The noise was either short (50 ms) or long (150 ms), with the long noise intended to elicit the sluggish MOCR. For a tone in quiet, mid-level hump WFs improved with ipsilateral noise for most listeners, but not with contralateral noise. For a tone in ipsilateral noise, WFs improved with contralateral noise for most listeners, but only when both noises were long. These results are consistent with MOCR-induced WF improvements, possibly via decreases in effects of compression and neural adaptation. PMID:26627798

Noise level in intensive care units of a public university hospital in Santa Marta (Colombia).

PubMed

Garrido Galindo, A P; Camargo Caicedo, Y; Vélez-Pereira, A M

2016-10-01

To evaluate the noise level in adult, pediatric and neonatal intensive care units of a university hospital in the city of Santa Marta (Colombia). A descriptive, observational, non-interventional study with follow-up over time was carried out. Continuous sampling was conducted for 20 days for each unit using a type i sound level meter, filter frequency in A weighting and Fast mode. We recorded the maximum values, the 90th percentile as background noise, and the continuous noise level. The mean hourly levels in the adult unit varied between 57.40±1.14-63.47±2.13dBA, with a maximum between 71.55±2.32-77.22±1.94dBA, and a background noise between 53.51±1.16-60.26±2.10dBA; in the pediatric unit the mean hourly levels varied between 57.07±3.07-65.72±2.46dBA, with a maximum of 68.69±3.57-79.06±2.34dBA, and a background noise between 53.33±3.54-61.96±2.85dBA; the neonatal unit in turn presented mean hourly values between 59.54±2.41-65.33±1.77dBA, with a maximum value between 67.20±2.13-77.65±3.74dBA, and a background noise between 55.02±2.03-58.70±1.95dBA. Analysis of variance revealed a significant difference between the hourly values and between the different units, with the time of day exhibiting a greater influence. The type of unit affects the noise levels in intensive care units, the pediatric unit showing the highest values and the adult unit the lowest values. However, the parameter exerting the greatest influence upon noise level is the time of day, with higher levels in the morning and evening, and lower levels at night and in the early morning. Copyright © 2015 Elsevier España, S.L.U. y SEMICYUC. All rights reserved.

Noise Gating Solar Images

NASA Astrophysics Data System (ADS)

DeForest, Craig; Seaton, Daniel B.; Darnell, John A.

2017-08-01

I present and demonstrate a new, general purpose post-processing technique, "3D noise gating", that can reduce image noise by an order of magnitude or more without effective loss of spatial or temporal resolution in typical solar applications.Nearly all scientific images are, ultimately, limited by noise. Noise can be direct Poisson "shot noise" from photon counting effects, or introduced by other means such as detector read noise. Noise is typically represented as a random variable (perhaps with location- or image-dependent characteristics) that is sampled once per pixel or once per resolution element of an image sequence. Noise limits many aspects of image analysis, including photometry, spatiotemporal resolution, feature identification, morphology extraction, and background modeling and separation.Identifying and separating noise from image signal is difficult. The common practice of blurring in space and/or time works because most image "signal" is concentrated in the low Fourier components of an image, while noise is evenly distributed. Blurring in space and/or time attenuates the high spatial and temporal frequencies, reducing noise at the expense of also attenuating image detail. Noise-gating exploits the same property -- "coherence" -- that we use to identify features in images, to separate image features from noise.Processing image sequences through 3-D noise gating results in spectacular (more than 10x) improvements in signal-to-noise ratio, while not blurring bright, resolved features in either space or time. This improves most types of image analysis, including feature identification, time sequence extraction, absolute and relative photometry (including differential emission measure analysis), feature tracking, computer vision, correlation tracking, background modeling, cross-scale analysis, visual display/presentation, and image compression.I will introduce noise gating, describe the method, and show examples from several instruments (including SDO/AIA , SDO/HMI, STEREO/SECCHI, and GOES-R/SUVI) that explore the benefits and limits of the technique.

Helicopter Rotor Noise Prediction: Background, Current Status, and Future Direction

NASA Technical Reports Server (NTRS)

Brentner, Kenneth S.

1997-01-01

Helicopter noise prediction is increasingly important. The purpose of this viewgraph presentation is to: 1) Put into perspective the recent progress; 2) Outline current prediction capabilities; 3) Forecast direction of future prediction research; 4) Identify rotorcraft noise prediction needs. The presentation includes an historical perspective, a description of governing equations, and the current status of source noise prediction.

An Investigation of Community Attitudes Toward Blast Noise. General Community Survey, Study Site 1

DTIC Science & Technology

2012-04-01

1 1.1.1 Blast noise and community impact ...P. Holland. ERDC/CERL TR-12-9 1 1 Introduction 1.1 Background 1.1.1 Blast noise and community impact In the United States, the number of...decade, has heightened the potential for noise generated by US military installations to negatively impact surrounding communities. For many years

Background Acoustics Levels in the 9x15 Wind Tunnel and Linear Array Testing

NASA Technical Reports Server (NTRS)

Stephens, David

2011-01-01

The background noise level in the 9x15 foot wind tunnel at NASA Glenn has been documented, and the results compare favorably with historical measurements. A study of recessed microphone mounting techniques was also conducted, and a recessed cavity with a micronic wire mesh screen reduces hydrodynamic noise by around 10 dB. A three-microphone signal processing technique can provide additional benefit, rejecting up to 15 dB of noise contamination at some frequencies. The screen and cavity system offers considerable benefit to test efficiency, although there are additional calibration requirements.

Joint Service Aircrew Mask (JSAM) - Tactical Aircraft (TA) A/P22P-14A Respirator Assembly (V)3: Noise Attenuation and Speech Intelligibility Performance with Double Hearing Protection, HGU-55A/P JHMCS Flight Helmet

DTIC Science & Technology

2017-03-01

in an environment 71-115 dB Sound Pressure Level (SPL) background pink noise. The speech intelligibility tests shall result in a Modified Rhyme... Test (MRT) score as listed below. Speech intelligibility testing shall be measured per ANSI S3.2 for each background pink noise level using a...minimum of ten talkers and of ten listeners. The test shall be conducted wearing the JSAM-TA using appropriate communication amplification. Test must

On the contribution of a stochastic background of gravitational radiation to the timing noise of pulsars

NASA Technical Reports Server (NTRS)

Mashhoon, B.

1982-01-01

The influence of a stochastic and isotropic background of gravitational radiation on timing measurements of pulsars is investigated, and it is shown that pulsar timing noise may be used to establish a significant upper limit of about 10 to the -10th on the total energy density of very long-wavelength stochastic gravitational waves. This places restriction on the strength of very long wavelength gravitational waves in the Friedmann model, and such a background is expected to have no significant effect on the approximately 3 K electromagnetic background radiation or on the dynamics of a cluster of galaxies.

The effect of changing the secondary task in dual-task paradigms for measuring listening effort.

PubMed

Picou, Erin M; Ricketts, Todd A

2014-01-01

The purpose of this study was to evaluate the effect of changing the secondary task in dual-task paradigms that measure listening effort. Specifically, the effects of increasing the secondary task complexity or the depth of processing on a paradigm's sensitivity to changes in listening effort were quantified in a series of two experiments. Specific factors investigated within each experiment were background noise and visual cues. Participants in Experiment 1 were adults with normal hearing (mean age 23 years) and participants in Experiment 2 were adults with mild sloping to moderately severe sensorineural hearing loss (mean age 60.1 years). In both experiments, participants were tested using three dual-task paradigms. These paradigms had identical primary tasks, which were always monosyllable word recognition. The secondary tasks were all physical reaction time measures. The stimulus for the secondary task varied by paradigm and was a (1) simple visual probe, (2) a complex visual probe, or (3) the category of word presented. In this way, the secondary tasks mainly varied from the simple paradigm by either complexity or depth of speech processing. Using all three paradigms, participants were tested in four conditions, (1) auditory-only stimuli in quiet, (2) auditory-only stimuli in noise, (3) auditory-visual stimuli in quiet, and (4) auditory-visual stimuli in noise. During auditory-visual conditions, the talker's face was visible. Signal-to-noise ratios used during conditions with background noise were set individually so word recognition performance was matched in auditory-only and auditory-visual conditions. In noise, word recognition performance was approximately 80% and 65% for Experiments 1 and 2, respectively. For both experiments, word recognition performance was stable across the three paradigms, confirming that none of the secondary tasks interfered with the primary task. In Experiment 1 (listeners with normal hearing), analysis of median reaction times revealed a significant main effect of background noise on listening effort only with the paradigm that required deep processing. Visual cues did not change listening effort as measured with any of the three dual-task paradigms. In Experiment 2 (listeners with hearing loss), analysis of median reaction times revealed expected significant effects of background noise using all three paradigms, but no significant effects of visual cues. None of the dual-task paradigms were sensitive to the effects of visual cues. Furthermore, changing the complexity of the secondary task did not change dual-task paradigm sensitivity to the effects of background noise on listening effort for either group of listeners. However, the paradigm whose secondary task involved deeper processing was more sensitive to the effects of background noise for both groups of listeners. While this paradigm differed from the others in several respects, depth of processing may be partially responsible for the increased sensitivity. Therefore, this paradigm may be a valuable tool for evaluating other factors that affect listening effort.

Higher songs of city birds may not be an individual response to noise.

PubMed

Zollinger, Sue Anne; Slater, Peter J B; Nemeth, Erwin; Brumm, Henrik

2017-08-16

It has been observed in many songbird species that populations in noisy urban areas sing with a higher minimum frequency than do matched populations in quieter, less developed areas. However, why and how this divergence occurs is not yet understood. We experimentally tested whether chronic noise exposure during vocal learning results in songs with higher minimum frequencies in great tits ( Parus major ), the first species for which a correlation between anthropogenic noise and song frequency was observed. We also tested vocal plasticity of adult great tits in response to changing background noise levels by measuring song frequency and amplitude as we changed noise conditions. We show that noise exposure during ontogeny did not result in songs with higher minimum frequencies. In addition, we found that adult birds did not make any frequency or song usage adjustments when their background noise conditions were changed after song crystallization. These results challenge the common view of vocal adjustments by city birds, as they suggest that either noise itself is not the causal force driving the divergence of song frequency between urban and forest populations, or that noise induces population-wide changes over a time scale of several generations rather than causing changes in individual behaviour. © 2017 The Author(s).

Single and Multiple Microphone Noise Reduction Strategies in Cochlear Implants

PubMed Central

Azimi, Behnam; Hu, Yi; Friedland, David R.

2012-01-01

To restore hearing sensation, cochlear implants deliver electrical pulses to the auditory nerve by relying on sophisticated signal processing algorithms that convert acoustic inputs to electrical stimuli. Although individuals fitted with cochlear implants perform well in quiet, in the presence of background noise, the speech intelligibility of cochlear implant listeners is more susceptible to background noise than that of normal hearing listeners. Traditionally, to increase performance in noise, single-microphone noise reduction strategies have been used. More recently, a number of approaches have suggested that speech intelligibility in noise can be improved further by making use of two or more microphones, instead. Processing strategies based on multiple microphones can better exploit the spatial diversity of speech and noise because such strategies rely mostly on spatial information about the relative position of competing sound sources. In this article, we identify and elucidate the most significant theoretical aspects that underpin single- and multi-microphone noise reduction strategies for cochlear implants. More analytically, we focus on strategies of both types that have been shown to be promising for use in current-generation implant devices. We present data from past and more recent studies, and furthermore we outline the direction that future research in the area of noise reduction for cochlear implants could follow. PMID:22923425

The Influence of Geography and Geology on Seismic Background Noise Levels Across the United States as Revealed by the Transportable Array

NASA Astrophysics Data System (ADS)

Anthony, R. E.; Ringler, A. T.; Holland, A. A.; Wilson, D. C.

2017-12-01

The EarthScope USArray Transportable Array (TA) has now covered the US with 3-component broadband seismometers at approximately 70 km station spacing and deployment durations of approximately 2 years. This unprecedented coverage, combined with high-quality and near homogenous installation techniques, offers a novel dataset in which to characterize spatially varying levels of background seismic noise across the United States. We present background noise maps in period bands of interest to earthquake and imaging seismology across the US (lower 48 states and Alaska). Early results from the contiguous 48 states demonstrate that ambient noise levels within the body wave period band (1-5 s) vary by > 20 dB (rel. 1 (m/s2)2/Hz) with the highest noise levels occurring at stations located within sedimentary basins and lowest within the mountain ranges of the Western US. Additionally, stations around the Great Lakes observe heightened noise levels in this band beyond the aforementioned basin amplification. We attribute this observation to local swell activity in the Great Lakes generating short-period microseism signals. This suggests that lake-generated microseisms may be a significant source of noise for Alaskan deployments situated in close proximity to lakes to facilitate float plane access. We further investigate how basin amplification and short-period lake microseism signals may noticeably impact detection and signal-to-noise of teleseismic body wave signals during certain time periods. At longer-periods (> 20 s), we generally observe larger noise levels on the horizontal components of stations situated in basins or on soft sediment, likely caused by locally induced tilt of the sensor. We will present similar analysis from the initial Alaska TA dataset to quantitatively assess how utilization of posthole sensors affects signal-to-noise for the long-period horizontal wavefield.

Analysis on spectra of hydroacoustic field in sonar cavity of the sandwich elastic wall structure

NASA Astrophysics Data System (ADS)

Xuetao, W.; Rui, H.; Weike, W.

2017-09-01

In this paper, the characteristics of the mechanical self - noise in sonar array cavity are studied by using the elastic flatbed - filled rectangular cavity parameterization model. Firstly, the analytic derivation of the vibration differential equation of the single layer, sandwich elastic wall plate structure and internal fluid coupling is carried out, and the modal method is used to solve it. Finally, the spectral characteristics of the acoustic field of rectangular cavity of different elastic wallboard materials are simulated and analyzed, which provides a theoretical reference for the prediction and control of sonar mechanical self-noise. In this paper, the sandwich board as control inside the dome background noise of a potential means were discussed, the dome background noise of qualitative prediction analysis and control has important theoretical significance.

Background Noise of the Aldeia da Serra Region (Portugal) from a temporary broad band network

NASA Astrophysics Data System (ADS)

Wachilala, Piedade; Borges, José; Caldeira, Bento; Bezzeghoud, Mourad

2017-04-01

In this study, we analyse seismic background noise to assess the effect of noise based on the detectability of a temporary network constituted by DOCTAR (Deep Ocean Test Array), who have been deployed in a period between 2011 and 2012 in Portugal mainland, and the Évora permanent seismic station. This network is constituted by 14 digital broadband stations (14 CMG-3ESP and one STS2 sensors) with a flat response between the 60 sec to 50 Hz, 24-bit and 120s to 60Hz respectively. The temporary network was operated in continuous recording mode (three-components) in a region located in the north of the region of Évora, within a radius of about 30 km around the village of Aldeia da Serra, region in which there is an important seismic activity in the context of Portugal mainland. We calculated power spectral densities of background noise for each station/component and compare them with high-noise model and low-noise model of Peterson (1993). We consider different for day and night local and for different periods of the year. Power spectral density estimates show moderate noise levels with all stations falling within the high and low bounds of Peterson (1993). Considering the results of the noise, we estimate the detection limit of each station and consequently the detectability of the network. From this information and taking in attention the events recorded during the period of DOCTAR operation we analyse the improvement promoted by this temporary network regarding the existent seismic networks to the local seismicity study. This work was partially supported by COMPETE 2020 program (POCI-01-0145-FEDER-007690 project). We acknowledge GFZ Potsdam for providing part of the data used in this study.

The effect of background noise on the word activation process in nonnative spoken-word recognition.

PubMed

Scharenborg, Odette; Coumans, Juul M J; van Hout, Roeland

2018-02-01

This article investigates 2 questions: (1) does the presence of background noise lead to a differential increase in the number of simultaneously activated candidate words in native and nonnative listening? And (2) do individual differences in listeners' cognitive and linguistic abilities explain the differential effect of background noise on (non-)native speech recognition? English and Dutch students participated in an English word recognition experiment, in which either a word's onset or offset was masked by noise. The native listeners outperformed the nonnative listeners in all listening conditions. Importantly, however, the effect of noise on the multiple activation process was found to be remarkably similar in native and nonnative listening. The presence of noise increased the set of candidate words considered for recognition in both native and nonnative listening. The results indicate that the observed performance differences between the English and Dutch listeners should not be primarily attributed to a differential effect of noise, but rather to the difference between native and nonnative listening. Additional analyses showed that word-initial information was found to be more important than word-final information during spoken-word recognition. When word-initial information was no longer reliably available word recognition accuracy dropped and word frequency information could no longer be used suggesting that word frequency information is strongly tied to the onset of words and the earliest moments of lexical access. Proficiency and inhibition ability were found to influence nonnative spoken-word recognition in noise, with a higher proficiency in the nonnative language and worse inhibition ability leading to improved recognition performance. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Detailed modeling of the statistical uncertainty of Thomson scattering measurements

NASA Astrophysics Data System (ADS)

Morton, L. A.; Parke, E.; Den Hartog, D. J.

2013-11-01

The uncertainty of electron density and temperature fluctuation measurements is determined by statistical uncertainty introduced by multiple noise sources. In order to quantify these uncertainties precisely, a simple but comprehensive model was made of the noise sources in the MST Thomson scattering system and of the resulting variance in the integrated scattered signals. The model agrees well with experimental and simulated results. The signal uncertainties are then used by our existing Bayesian analysis routine to find the most likely electron temperature and density, with confidence intervals. In the model, photonic noise from scattered light and plasma background light is multiplied by the noise enhancement factor (F) of the avalanche photodiode (APD). Electronic noise from the amplifier and digitizer is added. The amplifier response function shapes the signal and induces correlation in the noise. The data analysis routine fits a characteristic pulse to the digitized signals from the amplifier, giving the integrated scattered signals. A finite digitization rate loses information and can cause numerical integration error. We find a formula for the variance of the scattered signals in terms of the background and pulse amplitudes, and three calibration constants. The constants are measured easily under operating conditions, resulting in accurate estimation of the scattered signals' uncertainty. We measure F ≈ 3 for our APDs, in agreement with other measurements for similar APDs. This value is wavelength-independent, simplifying analysis. The correlated noise we observe is reproduced well using a Gaussian response function. Numerical integration error can be made negligible by using an interpolated characteristic pulse, allowing digitization rates as low as the detector bandwidth. The effect of background noise is also determined.

Computed tomography coronary stent imaging with iterative reconstruction: a trade-off study between medium kernel and sharp kernel.

PubMed

Zhou, Qijing; Jiang, Biao; Dong, Fei; Huang, Peiyu; Liu, Hongtao; Zhang, Minming

2014-01-01

To evaluate the improvement of iterative reconstruction in image space (IRIS) technique in computed tomographic (CT) coronary stent imaging with sharp kernel, and to make a trade-off analysis. Fifty-six patients with 105 stents were examined by 128-slice dual-source CT coronary angiography (CTCA). Images were reconstructed using standard filtered back projection (FBP) and IRIS with both medium kernel and sharp kernel applied. Image noise and the stent diameter were investigated. Image noise was measured both in background vessel and in-stent lumen as objective image evaluation. Image noise score and stent score were performed as subjective image evaluation. The CTCA images reconstructed with IRIS were associated with significant noise reduction compared to that of CTCA images reconstructed using FBP technique in both of background vessel and in-stent lumen (the background noise decreased by approximately 25.4% ± 8.2% in medium kernel (P

Underwater Ambient Noise. Proceedings of a Conference Held at SACLANTCEN on 11-14 May 1982. Volume 2. Unclassified Papers. Part 2

DTIC Science & Technology

1982-06-15

1 to 7-10 Acoustic ambient noise in the Barents Sea by 0. Grenness h ) 8-1 to 8-9 Depth dependence of directionality of ambient noise in the North...influence of ship’s noise on ambient noise measurements, by H . Bendig m) 13-1 to 13-12 -’Optimal detection and tracking of acoustical noise sources in...a time-varying environment, by H . Van Asselt n) 14-1 to 14-11 Influence of background-noise spatial coherence on high-resolution passive method - by

Critical assessment of day time traffic noise level at curbside open-air microenvironment of Kolkata City, India.

PubMed

Kundu Chowdhury, Anirban; Debsarkar, Anupam; Chakrabarty, Shibnath

2015-01-01

The objective of the research work is to assess day time traffic noise level at curbside open-air microenvironment of Kolkata city, India under heterogeneous environmental conditions. Prevailing traffic noise level in terms of A-weighted equivalent noise level (Leq) at the microenvironment was in excess of 12.6 ± 2.1 dB(A) from the day time standard of 65 dB(A) for commercial area recommended by the Central Pollution Control Board (CPCB) of India. Noise Climate and Traffic Noise Index of the microenvironment were accounted for 13 ± 1.8 dB(A) and 88.8 ± 6.1 dB(A) respectively. A correlation analysis explored that prevailing traffic noise level of the microenvironment had weak negative (-0.21; p < 0.01) and very weak positive (0.19; p < 0.01) correlation with air temperature and relative humidity. A Varimax rotated principal component analysis explored that motorized traffic volume had moderate positive loading with background noise component (L90, L95, L99) and prevailing traffic noise level had very strong positive loading with peak noise component (L1, L5, L10). Background and peak noise component cumulatively explained 80.98 % of variance in the data set. Traffic noise level at curbside open-air microenvironment of Kolkata City was higher than the standard recommended by CPCB of India. It was highly annoying also. Air temperature and relative humidity had little influence and the peak noise component had the most significant influence on the prevailing traffic noise level at curbside open-air microenvironment. Therefore, traffic noise level at the microenvironment of the city can be reduced with careful honking and driving.

Noise-invariant Neurons in the Avian Auditory Cortex: Hearing the Song in Noise

PubMed Central

Moore, R. Channing; Lee, Tyler; Theunissen, Frédéric E.

2013-01-01

Given the extraordinary ability of humans and animals to recognize communication signals over a background of noise, describing noise invariant neural responses is critical not only to pinpoint the brain regions that are mediating our robust perceptions but also to understand the neural computations that are performing these tasks and the underlying circuitry. Although invariant neural responses, such as rotation-invariant face cells, are well described in the visual system, high-level auditory neurons that can represent the same behaviorally relevant signal in a range of listening conditions have yet to be discovered. Here we found neurons in a secondary area of the avian auditory cortex that exhibit noise-invariant responses in the sense that they responded with similar spike patterns to song stimuli presented in silence and over a background of naturalistic noise. By characterizing the neurons' tuning in terms of their responses to modulations in the temporal and spectral envelope of the sound, we then show that noise invariance is partly achieved by selectively responding to long sounds with sharp spectral structure. Finally, to demonstrate that such computations could explain noise invariance, we designed a biologically inspired noise-filtering algorithm that can be used to separate song or speech from noise. This novel noise-filtering method performs as well as other state-of-the-art de-noising algorithms and could be used in clinical or consumer oriented applications. Our biologically inspired model also shows how high-level noise-invariant responses could be created from neural responses typically found in primary auditory cortex. PMID:23505354

Noise-invariant neurons in the avian auditory cortex: hearing the song in noise.

PubMed

Moore, R Channing; Lee, Tyler; Theunissen, Frédéric E

2013-01-01

Given the extraordinary ability of humans and animals to recognize communication signals over a background of noise, describing noise invariant neural responses is critical not only to pinpoint the brain regions that are mediating our robust perceptions but also to understand the neural computations that are performing these tasks and the underlying circuitry. Although invariant neural responses, such as rotation-invariant face cells, are well described in the visual system, high-level auditory neurons that can represent the same behaviorally relevant signal in a range of listening conditions have yet to be discovered. Here we found neurons in a secondary area of the avian auditory cortex that exhibit noise-invariant responses in the sense that they responded with similar spike patterns to song stimuli presented in silence and over a background of naturalistic noise. By characterizing the neurons' tuning in terms of their responses to modulations in the temporal and spectral envelope of the sound, we then show that noise invariance is partly achieved by selectively responding to long sounds with sharp spectral structure. Finally, to demonstrate that such computations could explain noise invariance, we designed a biologically inspired noise-filtering algorithm that can be used to separate song or speech from noise. This novel noise-filtering method performs as well as other state-of-the-art de-noising algorithms and could be used in clinical or consumer oriented applications. Our biologically inspired model also shows how high-level noise-invariant responses could be created from neural responses typically found in primary auditory cortex.

Development and Certification of Ultrasonic Background Noise Test (UBNT) System for use on the International Space Station (ISS)

NASA Technical Reports Server (NTRS)

Prosser, William H.; Madaras, Eric I.

2011-01-01

As a next step in the development and implementation of an on-board leak detection and localization system on the International Space Station (ISS), there is a documented need to obtain measurements of the ultrasonic background noise levels that exist within the ISS. This need is documented in the ISS Integrated Risk Management System (IRMA), Watch Item #4669. To address this, scientists and engineers from the Langley Research Center (LaRC) and the Johnson Space Center (JSC), proposed to the NASA Engineering and Safety Center (NESC) and the ISS Vehicle Office a joint assessment to develop a flight package as a Station Development Test Objective (SDTO) that would perform ultrasonic background noise measurements within the United States (US) controlled ISS structure. This document contains the results of the assessment

Changes to Articulatory Kinematics in Response to Loudness Cues in Individuals with Parkinson’s Disease

PubMed Central

Darling, Meghan; Huber, Jessica E.

2012-01-01

Purpose Individuals with Parkinson’s disease (PD) exhibit differences in displacement and velocity of the articulators as compared to older adults. The purpose of the current study was to examine effects of three loudness cues on articulatory movement patterns in individuals with PD. Methods Nine individuals diagnosed with idiopathic PD and 9 age- and sex- matched healthy controls produced sentences in four conditions: 1) comfortable loudness, 2) targeting 10dB above comfortable, 3) twice as loud as comfortable, and 4) in background noise. Lip and jaw kinematics and acoustic measurements were obtained. Results Both groups significantly increased sound pressure level (SPL) in the loud conditions as compared to comfortable. For the loud conditions, both groups had the highest SPL in background noise and 10dB and the lowest in twice as loud. Control participants produced the largest opening displacement in background noise and the smallest in twice as loud. Conversely, individuals with PD produced the largest opening displacement in twice as loud and the smallest in background noise. Conclusions Control participants and individuals with PD responded to cues to increase loudness in different ways. Changes in SPL may explain differences in kinematics for the control participants, but do not for individuals with PD. PMID:21386044

COSMIC INFRARED BACKGROUND FLUCTUATIONS AND ZODIACAL LIGHT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Arendt, Richard G.; Kashlinsky, A.; Moseley, S. H.

We performed a specific observational test to measure the effect that the zodiacal light can have on measurements of the spatial fluctuations of the near-IR background. Previous estimates of possible fluctuations caused by zodiacal light have often been extrapolated from observations of the thermal emission at longer wavelengths and low angular resolution or from IRAC observations of high-latitude fields where zodiacal light is faint and not strongly varying with time. The new observations analyzed here target the COSMOS field at low ecliptic latitude where the zodiacal light intensity varies by factors of ∼2 over the range of solar elongations atmore » which the field can be observed. We find that the white-noise component of the spatial power spectrum of the background is correlated with the modeled zodiacal light intensity. Roughly half of the measured white noise is correlated with the zodiacal light, but a more detailed interpretation of the white noise is hampered by systematic uncertainties that are evident in the zodiacal light model. At large angular scales (≳100″) where excess power above the white noise is observed, we find no correlation of the power with the modeled intensity of the zodiacal light. This test clearly indicates that the large-scale power in the infrared background is not being caused by the zodiacal light.« less

Cosmic Infrared Background Fluctuations and Zodiacal Light

NASA Astrophysics Data System (ADS)

Arendt, Richard G.; Kashlinsky, A.; Moseley, S. H.; Mather, J.

2016-06-01

We performed a specific observational test to measure the effect that the zodiacal light can have on measurements of the spatial fluctuations of the near-IR background. Previous estimates of possible fluctuations caused by zodiacal light have often been extrapolated from observations of the thermal emission at longer wavelengths and low angular resolution or from IRAC observations of high-latitude fields where zodiacal light is faint and not strongly varying with time. The new observations analyzed here target the COSMOS field at low ecliptic latitude where the zodiacal light intensity varies by factors of ˜2 over the range of solar elongations at which the field can be observed. We find that the white-noise component of the spatial power spectrum of the background is correlated with the modeled zodiacal light intensity. Roughly half of the measured white noise is correlated with the zodiacal light, but a more detailed interpretation of the white noise is hampered by systematic uncertainties that are evident in the zodiacal light model. At large angular scales (≳100″) where excess power above the white noise is observed, we find no correlation of the power with the modeled intensity of the zodiacal light. This test clearly indicates that the large-scale power in the infrared background is not being caused by the zodiacal light.

Voice Use Among Music Theory Teachers: A Voice Dosimetry and Self-Assessment Study.

PubMed

Schiller, Isabel S; Morsomme, Dominique; Remacle, Angélique

2017-07-25

This study aimed (1) to investigate music theory teachers' professional and extra-professional vocal loading and background noise exposure, (2) to determine the correlation between vocal loading and background noise, and (3) to determine the correlation between vocal loading and self-evaluation data. Using voice dosimetry, 13 music theory teachers were monitored for one workweek. The parameters analyzed were voice sound pressure level (SPL), fundamental frequency (F0), phonation time, vocal loading index (VLI), and noise SPL. Spearman correlation was used to correlate vocal loading parameters (voice SPL, F0, and phonation time) and noise SPL. Each day, the subjects self-assessed their voice using visual analog scales. VLI and self-evaluation data were correlated using Spearman correlation. Vocal loading parameters and noise SPL were significantly higher in the professional than in the extra-professional environment. Voice SPL, phonation time, and female subjects' F0 correlated positively with noise SPL. VLI correlated with self-assessed voice quality, vocal fatigue, and amount of singing and speaking voice produced. Teaching music theory is a profession with high vocal demands. More background noise is associated with increased vocal loading and may indirectly increase the risk for voice disorders. Correlations between VLI and self-assessments suggest that these teachers are well aware of their vocal demands and feel their effect on voice quality and vocal fatigue. Visual analog scales seem to represent a useful tool for subjective vocal loading assessment and associated symptoms in these professional voice users. Copyright © 2017 The Voice Foundation. Published by Elsevier Inc. All rights reserved.

Speech Discrimination Difficulties in High-Functioning Autism Spectrum Disorder Are Likely Independent of Auditory Hypersensitivity

PubMed Central

Dunlop, William A.; Enticott, Peter G.; Rajan, Ramesh

2016-01-01

Autism Spectrum Disorder (ASD), characterized by impaired communication skills and repetitive behaviors, can also result in differences in sensory perception. Individuals with ASD often perform normally in simple auditory tasks but poorly compared to typically developed (TD) individuals on complex auditory tasks like discriminating speech from complex background noise. A common trait of individuals with ASD is hypersensitivity to auditory stimulation. No studies to our knowledge consider whether hypersensitivity to sounds is related to differences in speech-in-noise discrimination. We provide novel evidence that individuals with high-functioning ASD show poor performance compared to TD individuals in a speech-in-noise discrimination task with an attentionally demanding background noise, but not in a purely energetic noise. Further, we demonstrate in our small sample that speech-hypersensitivity does not appear to predict performance in the speech-in-noise task. The findings support the argument that an attentional deficit, rather than a perceptual deficit, affects the ability of individuals with ASD to discriminate speech from background noise. Finally, we piloted a novel questionnaire that measures difficulty hearing in noisy environments, and sensitivity to non-verbal and verbal sounds. Psychometric analysis using 128 TD participants provided novel evidence for a difference in sensitivity to non-verbal and verbal sounds, and these findings were reinforced by participants with ASD who also completed the questionnaire. The study was limited by a small and high-functioning sample of participants with ASD. Future work could test larger sample sizes and include lower-functioning ASD participants. PMID:27555814

Sound propagation in urban areas: a periodic disposition of buildings.

PubMed

Picaut, J; Hardy, J; Simon, L

1999-10-01

A numerical simulation of background noise propagation is performed for a network of hexagonal buildings. The obtained results suggest that the prediction of background noise in urban spaces is possible by means of a modified diffusion equation using two parameters: the diffusion coefficient that expresses the spreading out of noise resulting from diffuse scattering and multiple reflections by buildings, and an attenuation term accounting for the wall absorption, atmospheric attenuation, and absorption by the open top. The dependence of the diffusion coefficient with geometrical shapes and the diffusive nature of the buildings are investigated in the case of a periodic disposition of hexagonal buildings.

Generation-recombination noise in extrinsic photoconductive detectors

NASA Technical Reports Server (NTRS)

Brukilacchio, T. J.; Skeldon, M. D.; Boyd, R. W.

1984-01-01

A theory of generation-recombination noise is presented and applied to the analysis of the performance limitations of extrinsic photoconductive detectors. The theory takes account both of the photoinduced generation of carriers and of thermal generation that is due to the finite temperature of the detector. Explicit formulas are derived that relate the detector response time, responsivity, and noise equivalent power to the material properties of the photoconductor (such as the presence of compensating impurities) and to the detector's operating conditions, such as its temperature and the presence of background radiation. The detector's performance is shown to degrade at high background levels because of saturation effects.

A study of the effect of flight density and background noise on V/STOL acceptability. [effective perceived noise level as measure of annoyance

NASA Technical Reports Server (NTRS)

Sternfeld, H., Jr.; Hinterkeuser, E. G.; Hackman, R. B.; Davis, J.

1974-01-01

A study was conducted in which test subjects evaluated the sounds of a helicopter, a turbofan STOL and a turbojet airplane while engaged in work and leisure activities. Exposure to a high repetitive density of the aircraft sounds did not make the individual sounds more annoying but did create an unacceptable environment. The application of a time duration term to db(A) resulted in a measure which compared favorably with EPNL as a predictor of annoyance. Temporal variations in background noise level had no significant effect on the rated annoyance.

Hyperspectral Imaging of a Turbine Engine Exhaust Plume to Determine Radiance, Temperature, and Concentration Spatial Distributions

DTIC Science & Technology

2009-03-01

the background, which manifests itself as shot noise ; the second term is dark current noise ; the third is electronics noise ; the fourth is...quantization noise ; and the fifth is spatial noise . Because of the ease at which one can increase the number of frames collected, within the limitations of...a computer and monitor. The FTS, a Bruker OPAG 22, was equipped with a mercury cadmium telluride ( MCT ) single- pixel detector responsive in the

Ultra-Low Noise Germanium Neutrino Detection system (ULGeN).

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cabrera-Palmer, Belkis; Barton, Paul

Monitoring nuclear power plant operation by measuring the antineutrino flux has become an active research field for safeguards and non-proliferation. We describe various efforts to demonstrate the feasibility of reactor monitoring based on the detection of the Coherent Neutrino Nucleus Scattering (CNNS) process with High Purity Germanium (HPGe) technology. CNNS detection for reactor antineutrino energies requires lowering the electronic noise in low-capacitance kg-scale HPGe detectors below 100 eV as well as stringent reduction in other particle backgrounds. Existing state- of-the-art detectors are limited to an electronic noise of 95 eV-FWHM. In this work, we employed an ultra-low capacitance point-contact detectormore » with a commercial integrated circuit preamplifier- on-a-chip in an ultra-low vibration mechanically cooled cryostat to achieve an electronic noise of 39 eV-FWHM at 43 K. We also present the results of a background measurement campaign at the Spallation Neutron Source to select the area with sufficient low background to allow a successful first-time measurement of the CNNS process.« less

Using Boosting Decision Trees in Gravitational Wave Searches triggered by Gamma-ray Bursts

NASA Astrophysics Data System (ADS)

Zuraw, Sarah; LIGO Collaboration

2015-04-01

The search for gravitational wave bursts requires the ability to distinguish weak signals from background detector noise. Gravitational wave bursts are characterized by their transient nature, making them particularly difficult to detect as they are similar to non-Gaussian noise fluctuations in the detector. The Boosted Decision Tree method is a powerful machine learning algorithm which uses Multivariate Analysis techniques to explore high-dimensional data sets in order to distinguish between gravitational wave signal and background detector noise. It does so by training with known noise events and simulated gravitational wave events. The method is tested using waveform models and compared with the performance of the standard gravitational wave burst search pipeline for Gamma-ray Bursts. It is shown that the method is able to effectively distinguish between signal and background events under a variety of conditions and over multiple Gamma-ray Burst events. This example demonstrates the usefulness and robustness of the Boosted Decision Tree and Multivariate Analysis techniques as a detection method for gravitational wave bursts. LIGO, UMass, PREP, NEGAP.

Accuracy of Cochlear Implant Recipients on Speech Reception in Background Music

PubMed Central

Gfeller, Kate; Turner, Christopher; Oleson, Jacob; Kliethermes, Stephanie; Driscoll, Virginia

2012-01-01

Objectives This study (a) examined speech recognition abilities of cochlear implant (CI) recipients in the spectrally complex listening condition of three contrasting types of background music, and (b) compared performance based upon listener groups: CI recipients using conventional long-electrode (LE) devices, Hybrid CI recipients (acoustic plus electric stimulation), and normal-hearing (NH) adults. Methods We tested 154 LE CI recipients using varied devices and strategies, 21 Hybrid CI recipients, and 49 NH adults on closed-set recognition of spondees presented in three contrasting forms of background music (piano solo, large symphony orchestra, vocal solo with small combo accompaniment) in an adaptive test. Outcomes Signal-to-noise thresholds for speech in music (SRTM) were examined in relation to measures of speech recognition in background noise and multi-talker babble, pitch perception, and music experience. Results SRTM thresholds varied as a function of category of background music, group membership (LE, Hybrid, NH), and age. Thresholds for speech in background music were significantly correlated with measures of pitch perception and speech in background noise thresholds; auditory status was an important predictor. Conclusions Evidence suggests that speech reception thresholds in background music change as a function of listener age (with more advanced age being detrimental), structural characteristics of different types of music, and hearing status (residual hearing). These findings have implications for everyday listening conditions such as communicating in social or commercial situations in which there is background music. PMID:23342550

Updating working memory in aircraft noise and speech noise causes different fMRI activations.

PubMed

Saetrevik, Bjørn; Sörqvist, Patrik

2015-02-01

The present study used fMRI/BOLD neuroimaging to investigate how visual-verbal working memory is updated when exposed to three different background-noise conditions: speech noise, aircraft noise and silence. The number-updating task that was used can distinguish between "substitution processes," which involve adding new items to the working memory representation and suppressing old items, and "exclusion processes," which involve rejecting new items and maintaining an intact memory set. The current findings supported the findings of a previous study by showing that substitution activated the dorsolateral prefrontal cortex, the posterior medial frontal cortex and the parietal lobes, whereas exclusion activated the anterior medial frontal cortex. Moreover, the prefrontal cortex was activated more by substitution processes when exposed to background speech than when exposed to aircraft noise. These results indicate that (a) the prefrontal cortex plays a special role when task-irrelevant materials should be denied access to working memory and (b) that, when compensating for different types of noise, either different cognitive mechanisms are involved or those cognitive mechanisms that are involved are involved to different degrees. © 2014 The Authors. Scandinavian Journal of Psychology published by Scandinavian Psychological Associations and John Wiley & Sons Ltd.

Development of Trivia Game for speech understanding in background noise.

PubMed

Schwartz, Kathryn; Ringleb, Stacie I; Sandberg, Hilary; Raymer, Anastasia; Watson, Ginger S

2015-01-01

Listening in noise is an everyday activity and poses a challenge for many people. To improve the ability to understand speech in noise, a computerized auditory rehabilitation game was developed. In Trivia Game players are challenged to answer trivia questions spoken aloud. As players progress through the game, the level of background noise increases. A study using Trivia Game was conducted as a proof-of-concept investigation in healthy participants. College students with normal hearing were randomly assigned to a control (n = 13) or a treatment (n = 14) group. Treatment participants played Trivia Game 12 times over a 4-week period. All participants completed objective (auditory-only and audiovisual formats) and subjective listening in noise measures at baseline and 4 weeks later. There were no statistical differences between the groups at baseline. At post-test, the treatment group significantly improved their overall speech understanding in noise in the audiovisual condition and reported significant benefits in their functional listening abilities. Playing Trivia Game improved speech understanding in noise in healthy listeners. Significant findings for the audiovisual condition suggest that participants improved face-reading abilities. Trivia Game may be a platform for investigating changes in speech understanding in individuals with sensory, linguistic and cognitive impairments.

Your attention please: increasing ambient noise levels elicits a change in communication behaviour in humpback whales (Megaptera novaeangliae)

PubMed Central

Dunlop, Rebecca A.; Cato, Douglas H.; Noad, Michael J.

2010-01-01

High background noise is an important obstacle in successful signal detection and perception of an intended acoustic signal. To overcome this problem, many animals modify their acoustic signal by increasing the repetition rate, duration, amplitude or frequency range of the signal. An alternative method to ensure successful signal reception, yet to be tested in animals, involves the use of two different types of signal, where one signal type may enhance the other in periods of high background noise. Humpback whale communication signals comprise two different types: vocal signals, and surface-generated signals such as ‘breaching’ or ‘pectoral slapping’. We found that humpback whales gradually switched from primarily vocal to primarily surface-generated communication in increasing wind speeds and background noise levels, though kept both signal types in their repertoire. Vocal signals have the advantage of having higher information content but may have the disadvantage of loosing this information in a noisy environment. Surface-generated sounds have energy distributed over a greater frequency range and may be less likely to become confused in periods of high wind-generated noise but have less information content when compared with vocal sounds. Therefore, surface-generated sounds may improve detection or enhance the perception of vocal signals in a noisy environment. PMID:20392731

Your attention please: increasing ambient noise levels elicits a change in communication behaviour in humpback whales (Megaptera novaeangliae).

PubMed

Dunlop, Rebecca A; Cato, Douglas H; Noad, Michael J

2010-08-22

High background noise is an important obstacle in successful signal detection and perception of an intended acoustic signal. To overcome this problem, many animals modify their acoustic signal by increasing the repetition rate, duration, amplitude or frequency range of the signal. An alternative method to ensure successful signal reception, yet to be tested in animals, involves the use of two different types of signal, where one signal type may enhance the other in periods of high background noise. Humpback whale communication signals comprise two different types: vocal signals, and surface-generated signals such as 'breaching' or 'pectoral slapping'. We found that humpback whales gradually switched from primarily vocal to primarily surface-generated communication in increasing wind speeds and background noise levels, though kept both signal types in their repertoire. Vocal signals have the advantage of having higher information content but may have the disadvantage of loosing this information in a noisy environment. Surface-generated sounds have energy distributed over a greater frequency range and may be less likely to become confused in periods of high wind-generated noise but have less information content when compared with vocal sounds. Therefore, surface-generated sounds may improve detection or enhance the perception of vocal signals in a noisy environment.

Influence of Spatial and Chromatic Noise on Luminance Discrimination.

PubMed

Miquilini, Leticia; Walker, Natalie A; Odigie, Erika A; Guimarães, Diego Leite; Salomão, Railson Cruz; Lacerda, Eliza Maria Costa Brito; Cortes, Maria Izabel Tentes; de Lima Silveira, Luiz Carlos; Fitzgerald, Malinda E C; Ventura, Dora Fix; Souza, Givago Silva

2017-12-05

Pseudoisochromatic figures are designed to base discrimination of a chromatic target from a background solely on the chromatic differences. This is accomplished by the introduction of luminance and spatial noise thereby eliminating these two dimensions as cues. The inverse rationale could also be applied to luminance discrimination, if spatial and chromatic noise are used to mask those cues. In this current study estimate of luminance contrast thresholds were conducted using a novel stimulus, based on the use of chromatic and spatial noise to mask the use of these cues in a luminance discrimination task. This was accomplished by presenting stimuli composed of a mosaic of circles colored randomly. A Landolt-C target differed from the background only by the luminance. The luminance contrast thresholds were estimated for different chromatic noise saturation conditions and compared to luminance contrast thresholds estimated using the same target in a non-mosaic stimulus. Moreover, the influence of the chromatic content in the noise on the luminance contrast threshold was also investigated. Luminance contrast threshold was dependent on the chromaticity noise strength. It was 10-fold higher than thresholds estimated from non-mosaic stimulus, but they were independent of colour space location in which the noise was modulated. The present study introduces a new method to investigate luminance vision intended for both basic science and clinical applications.

Understanding perception of active noise control system through multichannel EEG analysis.

PubMed

Bagha, Sangeeta; Tripathy, R K; Nanda, Pranati; Preetam, C; Das, Debi Prasad

2018-06-01

In this Letter, a method is proposed to investigate the effect of noise with and without active noise control (ANC) on multichannel electroencephalogram (EEG) signal. The multichannel EEG signal is recorded during different listening conditions such as silent, music, noise, ANC with background noise and ANC with both background noise and music. The multiscale analysis of EEG signal of each channel is performed using the discrete wavelet transform. The multivariate multiscale matrices are formulated based on the sub-band signals of each EEG channel. The singular value decomposition is applied to the multivariate matrices of multichannel EEG at significant scales. The singular value features at significant scales and the extreme learning machine classifier with three different activation functions are used for classification of multichannel EEG signal. The experimental results demonstrate that, for ANC with noise and ANC with noise and music classes, the proposed method has sensitivity values of 75.831% ( p < 0.001 ) and 99.31% ( p < 0.001 ), respectively. The method has an accuracy value of 83.22% for the classification of EEG signal with music and ANC with music as stimuli. The important finding of this study is that by the introduction of ANC, music can be better perceived by the human brain.

Effects of noise levels and call types on the source levels of killer whale calls.

PubMed

Holt, Marla M; Noren, Dawn P; Emmons, Candice K

2011-11-01

Accurate parameter estimates relevant to the vocal behavior of marine mammals are needed to assess potential effects of anthropogenic sound exposure including how masking noise reduces the active space of sounds used for communication. Information about how these animals modify their vocal behavior in response to noise exposure is also needed for such assessment. Prior studies have reported variations in the source levels of killer whale sounds, and a more recent study reported that killer whales compensate for vessel masking noise by increasing their call amplitude. The objectives of the current study were to investigate the source levels of a variety of call types in southern resident killer whales while also considering background noise level as a likely factor related to call source level variability. The source levels of 763 discrete calls along with corresponding background noise were measured over three summer field seasons in the waters surrounding the San Juan Islands, WA. Both noise level and call type were significant factors on call source levels (1-40 kHz band, range of 135.0-175.7 dB(rms) re 1 [micro sign]Pa at 1 m). These factors should be considered in models that predict how anthropogenic masking noise reduces vocal communication space in marine mammals.

The ESL Noise Test: Cultural Differences in Affect and Performance.

ERIC Educational Resources Information Center

Hansen, Lynne

This study investigates cultural differences in second language aural comprehension levels among Asians under the constraints of background noise. It is determined that noise is an important component of language proficiency, for it is found where most interactions take place. Students from Hong Kong, Seoul (Korea), Tokyo (Japan), and the South…

Children's Perception of Conversational and Clear American-English Vowels in Noise

ERIC Educational Resources Information Center

Leone, Dorothy; Levy, Erika S.

2015-01-01

Purpose: Much of a child's day is spent listening to speech in the presence of background noise. Although accurate vowel perception is important for listeners' accurate speech perception and comprehension, little is known about children's vowel perception in noise. "Clear speech" is a speech style frequently used by talkers in the…

The a priori SDR Estimation Techniques with Reduced Speech Distortion for Acoustic Echo and Noise Suppression

NASA Astrophysics Data System (ADS)

Thoonsaengngam, Rattapol; Tangsangiumvisai, Nisachon

This paper proposes an enhanced method for estimating the a priori Signal-to-Disturbance Ratio (SDR) to be employed in the Acoustic Echo and Noise Suppression (AENS) system for full-duplex hands-free communications. The proposed a priori SDR estimation technique is modified based upon the Two-Step Noise Reduction (TSNR) algorithm to suppress the background noise while preserving speech spectral components. In addition, a practical approach to determine accurately the Echo Spectrum Variance (ESV) is presented based upon the linear relationship assumption between the power spectrum of far-end speech and acoustic echo signals. The ESV estimation technique is then employed to alleviate the acoustic echo problem. The performance of the AENS system that employs these two proposed estimation techniques is evaluated through the Echo Attenuation (EA), Noise Attenuation (NA), and two speech distortion measures. Simulation results based upon real speech signals guarantee that our improved AENS system is able to mitigate efficiently the problem of acoustic echo and background noise, while preserving the speech quality and speech intelligibility.

Evaluation of different signal processing options in unilateral and bilateral cochlear freedom implant recipients using R-Space background noise.

PubMed

Brockmeyer, Alison M; Potts, Lisa G

2011-02-01

Difficulty understanding in background noise is a common complaint of cochlear implant (CI) recipients. Programming options are available to improve speech recognition in noise for CI users including automatic dynamic range optimization (ADRO), autosensitivity control (ASC), and a two-stage adaptive beamforming algorithm (BEAM). However, the processing option that results in the best speech recognition in noise is unknown. In addition, laboratory measures of these processing options often show greater degrees of improvement than reported by participants in everyday listening situations. To address this issue, Compton-Conley and colleagues developed a test system to replicate a restaurant environment. The R-SPACE™ consists of eight loudspeakers positioned in a 360 degree arc and utilizes a recording made at a restaurant of background noise. The present study measured speech recognition in the R-SPACE with four processing options: standard dual-port directional (STD), ADRO, ASC, and BEAM. A repeated-measures, within-subject design was used to evaluate the four different processing options at two noise levels. Twenty-seven unilateral and three bilateral adult Nucleus Freedom CI recipients. The participants' everyday program (with no additional processing) was used as the STD program. ADRO, ASC, and BEAM were added individually to the STD program to create a total of four programs. Participants repeated Hearing in Noise Test sentences presented at 0 degrees azimuth with R-SPACE restaurant noise at two noise levels, 60 and 70 dB SPL. The reception threshold for sentences (RTS) was obtained for each processing condition and noise level. In 60 dB SPL noise, BEAM processing resulted in the best RTS, with a significant improvement over STD and ADRO processing. In 70 dB SPL noise, ASC and BEAM processing had significantly better mean RTSs compared to STD and ADRO processing. Comparison of noise levels showed that STD and BEAM processing resulted in significantly poorer RTSs in 70 dB SPL noise compared to the performance with these processing conditions in 60 dB SPL noise. Bilateral participants demonstrated a bilateral improvement compared to the better monaural condition for both noise levels and all processing conditions, except ASC in 60 dB SPL noise. The results of this study suggest that the use of processing options that utilize noise reduction, like those available in ASC and BEAM, improve a CI recipient's ability to understand speech in noise in listening situations similar to those experienced in the real world. The choice of the best processing option is dependent on the noise level, with BEAM best at moderate noise levels and ASC best at loud noise levels for unilateral CI recipients. Therefore, multiple noise programs or a combination of processing options may be necessary to provide CI users with the best performance in a variety of listening situations. American Academy of Audiology.

Cueing properties of the decrease of white noise intensity for avoidance conditioning in cats.

PubMed

Zieliński, K

1979-01-01

In the main experiment two groups of 6 cats each were trained in active bar-pressing avoidance to a CS consisting of either a 10 dB or 20 dB decrease of the background white noise of 70 dB intensity. The two groups did not differ in rapidity of learning, however cats trained to the greater change .in background noise performed avoidance responses with shorter latencies than did cats trained to smaller change. Within-groups comparisons of cumulative distributions of response latencies for consecutive Vincentized fifths of avoidance acquisition showed the greatest changes in the region of latencies longer than the median latency of instrumental responses. On the other hand, the effects of CS intensity found in between-groups comparisons were located in the region of latencies shorter than the median latency of either group. Comparisons with data obtained in a complementary experiment employing additional 17 cats showed that subjects trained to stimuli less intense than the background noise level were marked by an exceptionally low level of avoidance responding with latencies shorter than 1.1 s, which was lower than expected from the probability of intertrial responses for this period of time. Due to this property of stimuli less intense than the background, the distributions of response latencies were moved to the right, in effect, prefrontal lesions influenced a greater part of latency distributions than in cats trained to stimuli more intense than the background.

Neural Timing is Linked to Speech Perception in Noise

PubMed Central

Samira, Anderson; Erika, Skoe; Bharath, Chandrasekaran; Nina, Kraus

2010-01-01

Understanding speech in background noise is challenging for every listener, including those with normal peripheral hearing. This difficulty is due in part to the disruptive effects of noise on neural synchrony, resulting in degraded representation of speech at cortical and subcortical levels as reflected by electrophysiological responses. These problems are especially pronounced in clinical populations such as children with learning impairments. Given the established effects of noise on evoked responses, we hypothesized that listening-in-noise problems are associated with degraded processing of timing information at the brainstem level. Participants (66 children, ages 8 to 14 years, 22 females) were divided into groups based on their performance on clinical measures of speech-in-noise perception (SIN) and reading. We compared brainstem responses to speech syllables between top and bottom SIN and reading groups in the presence and absence of competing multi-talker babble. In the quiet condition, neural response timing was equivalent between groups. In noise, however, the bottom groups exhibited greater neural delays relative to the top groups. Group-specific timing delays occurred exclusively in response to the noise-vulnerable formant transition, not to the more perceptually-robust, steady-state portion of the stimulus. These results demonstrate that neural timing is disrupted by background noise and that greater disruptions are associated with the inability to perceive speech in challenging listening conditions. PMID:20371812

Target detection in GPR data using joint low-rank and sparsity constraints

NASA Astrophysics Data System (ADS)

Bouzerdoum, Abdesselam; Tivive, Fok Hing Chi; Abeynayake, Canicious

2016-05-01

In ground penetrating radars, background clutter, which comprises the signals backscattered from the rough, uneven ground surface and the background noise, impairs the visualization of buried objects and subsurface inspections. In this paper, a clutter mitigation method is proposed for target detection. The removal of background clutter is formulated as a constrained optimization problem to obtain a low-rank matrix and a sparse matrix. The low-rank matrix captures the ground surface reflections and the background noise, whereas the sparse matrix contains the target reflections. An optimization method based on split-Bregman algorithm is developed to estimate these two matrices from the input GPR data. Evaluated on real radar data, the proposed method achieves promising results in removing the background clutter and enhancing the target signature.

Infants born very preterm react to variations of the acoustic environment in their incubator from a minimum signal-to-noise ratio threshold of 5 to 10 dBA.

PubMed

Kuhn, Pierre; Zores, Claire; Pebayle, Thierry; Hoeft, Alain; Langlet, Claire; Escande, Benoît; Astruc, Dominique; Dufour, André

2012-04-01

Very early preterm infants (VPIs) are exposed to unpredictable noise in neonatal intensive care units. Their ability to perceive moderate acoustic environmental changes has not been fully investigated. Physiological values of the 598 isolated sound peaks (SPs) that were 5-10 and 10-15 dB slow-response A (dBA) above background noise levels and that occurred during infants' sleep varied significantly, indicating that VPIs detect them. Exposure to 10-15 dBA SPs during active sleep significantly increased mean heart rate and decreased mean respiratory rate and mean systemic and cerebral oxygen saturations relative to baseline. VPIs are sensitive to changes in their nosocomial acoustic environment, with a minimal signal-to-noise ratio (SNR) threshold of 5-10 dBA. These acoustic changes can alter their well-being. In this observational study, we evaluated their differential auditory sensitivity to sound-pressure level (SPL) increments below 70-75 dBA equivalent continuous level in their incubators. Environmental (SPL and audio recording), physiological, cerebral, and behavioral data were prospectively collected over 10 h in 26 VPIs (GA 28 (26-31) wk). SPs emerging from background noise levels were identified and newborns' arousal states at the time of SPs were determined. Changes in parameters were compared over 5-s periods between baseline and the 40 s following the SPs depending on their SNR thresholds above background noise.

Figure of merit for direct-detection optical channels

NASA Technical Reports Server (NTRS)

Chen, C.-C.

1992-01-01

The capacity and sensitivity of a direct-detection optical channel are calculated and compared to those of a white Gaussian noise channel. Unlike Gaussian channels in which the receiver performance can be characterized using the noise temperature, the performance of the direct-detection channel depends on both signal and background noise, as well as the ratio of peak to average signal power. Because of the signal-power dependence of the optical channel, actual performance of the channel can be evaluated only by considering both transmit and receive ends of the systems. Given the background noise power and the modulation bandwidth, however, the theoretically optimum receiver sensitivity can be calculated. This optimum receiver sensitivity can be used to define the equivalent receiver noise temperature and calculate the corresponding G/T product. It should be pointed out, however, that the receiver sensitivity is a function of signal power, and care must be taken to avoid deriving erroneous projections of the direct-detection channel performance.

Regulation of Cortical Dynamic Range by Background Synaptic Noise and Feedforward Inhibition

PubMed Central

Khubieh, Ayah; Ratté, Stéphanie; Lankarany, Milad; Prescott, Steven A.

2016-01-01

The cortex encodes a broad range of inputs. This breadth of operation requires sensitivity to weak inputs yet non-saturating responses to strong inputs. If individual pyramidal neurons were to have a narrow dynamic range, as previously claimed, then staggered all-or-none recruitment of those neurons would be necessary for the population to achieve a broad dynamic range. Contrary to this explanation, we show here through dynamic clamp experiments in vitro and computer simulations that pyramidal neurons have a broad dynamic range under the noisy conditions that exist in the intact brain due to background synaptic input. Feedforward inhibition capitalizes on those noise effects to control neuronal gain and thereby regulates the population dynamic range. Importantly, noise allows neurons to be recruited gradually and occludes the staggered recruitment previously attributed to heterogeneous excitation. Feedforward inhibition protects spike timing against the disruptive effects of noise, meaning noise can enable the gain control required for rate coding without compromising the precise spike timing required for temporal coding. PMID:26209846

[Perception features of emotional intonation of short pseudowords].

PubMed

Dmitrieva, E S; Gel'man, V Ia; Zaĭtseva, K A; Orlov, A M

2012-01-01

Reaction time and recognition accuracy of speech emotional intonations in short meaningless words that differed only in one phoneme with background noise and without it were studied in 49 adults of 20-79 years old. The results were compared with the same parameters of emotional intonations in intelligent speech utterances under similar conditions. Perception of emotional intonations at different linguistic levels (phonological and lexico-semantic) was found to have both common features and certain peculiarities. Recognition characteristics of emotional intonations depending on gender and age of listeners appeared to be invariant with regard to linguistic levels of speech stimuli. Phonemic composition of pseudowords was found to influence the emotional perception, especially against the background noise. The most significant stimuli acoustic characteristic responsible for the perception of speech emotional prosody in short meaningless words under the two experimental conditions, i.e. with and without background noise, was the fundamental frequency variation.

A novel Kalman filter based video image processing scheme for two-photon fluorescence microscopy

NASA Astrophysics Data System (ADS)

Sun, Wenqing; Huang, Xia; Li, Chunqiang; Xiao, Chuan; Qian, Wei

2016-03-01

Two-photon fluorescence microscopy (TPFM) is a perfect optical imaging equipment to monitor the interaction between fast moving viruses and hosts. However, due to strong unavoidable background noises from the culture, videos obtained by this technique are too noisy to elaborate this fast infection process without video image processing. In this study, we developed a novel scheme to eliminate background noises, recover background bacteria images and improve video qualities. In our scheme, we modified and implemented the following methods for both host and virus videos: correlation method, round identification method, tree-structured nonlinear filters, Kalman filters, and cell tracking method. After these procedures, most of noises were eliminated and host images were recovered with their moving directions and speed highlighted in the videos. From the analysis of the processed videos, 93% bacteria and 98% viruses were correctly detected in each frame on average.

Phase-Noise and Amplitude-Noise Measurement of Low-Power Signals

NASA Technical Reports Server (NTRS)

Rubiola, Enrico; Salik, Ertan; Yu, Nan; Maleki, Lute

2004-01-01

Measuring the phase fluctuation between a pair of low-power microwave signals, the signals must be amplified before detection. In such cases the phase noise of the amplifier pair is the main cause of 1/f background noise of the instrument. this article proposes a scheme that makes amplification possible while rejecting the close in 1/f (flicker) noise of the two amplifiers. Noise rejection, which relies upon the understanding of the amplifier noise mechanism does not require averaging. Therefore, our scheme can also be the detector of a closed loop noise reduction system. the first prototype, compared to a traditional saturated mixer system under the same condition, show a 24 dB noise reduction of the 1/f region.

Increased visual sensitivity following periods of dim illumination.

PubMed

McKeown, Alex S; Kraft, Timothy W; Loop, Michael S

2015-02-19

We measured changes in the sensitivity of the human rod pathway by testing visual reaction times before and after light adaptation. We targeted a specific range of conditioning light intensities to see if a physiological adaptation recently discovered in mouse rods is observable at the perceptual level in humans. We also measured the noise spectrum of single mouse rods due to the importance of the signal-to-noise ratio in rod to rod bipolar cell signal transfer. Using the well-defined relationship between stimulus intensity and reaction time (Piéron's law), we measured the reaction times of eight human subjects (ages 24-66) to scotopic test flashes of a single intensity before and after the presentation of a 3-minute background. We also made recordings from single mouse rods and processed the cellular noise spectrum before and after similar conditioning exposures. Subject reaction times to a fixed-strength stimulus were fastest 5 seconds after conditioning background exposure (79% ± 1% of the preconditioning mean, in darkness) and were significantly faster for the first 12 seconds after background exposure (P < 0.01). During the period of increased rod sensitivity, the continuous noise spectrum of individual mouse rods was not significantly increased. A decrease in human reaction times to a dim flash after conditioning background exposure may originate in rod photoreceptors through a transient increase in the sensitivity of the phototransduction cascade. There is no accompanying increase in rod cellular noise, allowing for reliable transmission of larger rod signals after conditioning exposures and the observed increase in perceptual sensitivity. Copyright 2015 The Association for Research in Vision and Ophthalmology, Inc.

A Stochastic Kinematic Model of Class Averaging in Single-Particle Electron Microscopy

PubMed Central

Park, Wooram; Midgett, Charles R.; Madden, Dean R.; Chirikjian, Gregory S.

2011-01-01

Single-particle electron microscopy is an experimental technique that is used to determine the 3D structure of biological macromolecules and the complexes that they form. In general, image processing techniques and reconstruction algorithms are applied to micrographs, which are two-dimensional (2D) images taken by electron microscopes. Each of these planar images can be thought of as a projection of the macromolecular structure of interest from an a priori unknown direction. A class is defined as a collection of projection images with a high degree of similarity, presumably resulting from taking projections along similar directions. In practice, micrographs are very noisy and those in each class are aligned and averaged in order to reduce the background noise. Errors in the alignment process are inevitable due to noise in the electron micrographs. This error results in blurry averaged images. In this paper, we investigate how blurring parameters are related to the properties of the background noise in the case when the alignment is achieved by matching the mass centers and the principal axes of the experimental images. We observe that the background noise in micrographs can be treated as Gaussian. Using the mean and variance of the background Gaussian noise, we derive equations for the mean and variance of translational and rotational misalignments in the class averaging process. This defines a Gaussian probability density on the Euclidean motion group of the plane. Our formulation is validated by convolving the derived blurring function representing the stochasticity of the image alignments with the underlying noiseless projection and comparing with the original blurry image. PMID:21660125

Test-section noise of the Ames 7 by 10-foot wind tunnel no. 1

NASA Technical Reports Server (NTRS)

Soderman, P. T.

1976-01-01

An investigation was made of the test-section noise levels at various wind speeds in the Ames 7- by 10-Foot Wind Tunnel No. 1. No model was in the test section. Results showed that aerodynamic noise from various struts used to monitor flow conditions in the test section dominated the wind-tunnel background noise over much of the frequency spectrum. A tapered microphone stand with a thin trailing edge generated less noise than did a constant-chord strut with a blunt trailing edge. Noise from small holes in the test-section walls was insignificant.

Aircraft measurement of radio frequency noise at 121.5 MHz, 243 MHz and 406 MHz

NASA Technical Reports Server (NTRS)

Taylor, R. E.; Hill, J. S.

1977-01-01

An airborne survey measurement of terrestrial radio-frequency noise over U.S. metropolitan areas was carried out at 121.5, 243 and 406 MHz with horizontal-polarization monopole antennas. Flights were at 25,000 feet altitude. Radio-noise measurements, expressed in equivalent antenna-noise temperature, indicate a steady-background noise temperature of 572,000 K, at 121.5 MHz, during daylight over New York City. This data is helpful in compiling radio-noise temperature maps; in turn useful for designing satellite-aided, emergency-distress search and rescue communication systems.

Optical Johnson noise thermometry

NASA Technical Reports Server (NTRS)

Shepard, R. L.; Blalock, T. V.; Maxey, L. C.; Roberts, M. J.; Simpson, M. L.

1989-01-01

A concept is being explored that an optical analog of the electrical Johnson noise may be used to measure temperature independently of emissivity. The concept is that a laser beam may be modulated on reflection from a hot surface by interaction of the laser photons with the thermally agitated conduction electrons or the lattice phonons, thereby adding noise to the reflected laser beam. If the reflectance noise can be detected and quantified in a background of other noise in the optical and signal processing systems, the reflectance noise may provide a noncontact measurement of the absolute surface temperature and may be independent of the surface's emissivity.

Distracted While Reading? Changing to a Hard-to-Read Font Shields against the Effects of Environmental Noise and Speech on Text Memory

PubMed Central

Halin, Niklas

2016-01-01

The purpose of this study was to investigate the distractive effects of background speech, aircraft noise and road traffic noise on text memory and particularly to examine if displaying the texts in a hard-to-read font can shield against the detrimental effects of these types of background sounds. This issue was addressed in an experiment where 56 students read shorter texts about different classes of fictitious creatures (i.e., animals, fishes, birds, and dinosaurs) against a background of the aforementioned background sounds respectively and silence. For half of the participants the texts were displayed in an easy-to-read font (i.e., Times New Roman) and for the other half in a hard-to-read font (i.e., Haettenschweiler). The dependent measure was the proportion correct answers on the multiple-choice tests that followed each sound condition. Participants’ performance in the easy-to-read font condition was significantly impaired by all three background sound conditions compared to silence. In contrast, there were no effects of the three background sound conditions compared to silence in the hard-to-read font condition. These results suggest that an increase in task demand—by displaying the text in a hard-to-read font—shields against various types of distracting background sounds by promoting a more steadfast locus-of-attention and by reducing the processing of background sound. PMID:27555834

Expected Seismicity and the Seismic Noise Environment of Europa

NASA Astrophysics Data System (ADS)

Panning, Mark P.; Stähler, Simon C.; Huang, Hsin-Hua; Vance, Steven D.; Kedar, Sharon; Tsai, Victor C.; Pike, William T.; Lorenz, Ralph D.

2018-01-01

Seismic data will be a vital geophysical constraint on internal structure of Europa if we land instruments on the surface. Quantifying expected seismic activity on Europa both in terms of large, recognizable signals and ambient background noise is important for understanding dynamics of the moon, as well as interpretation of potential future data. Seismic energy sources will likely include cracking in the ice shell and turbulent motion in the oceans. We define a range of models of seismic activity in Europa's ice shell by assuming each model follows a Gutenberg-Richter relationship with varying parameters. A range of cumulative seismic moment release between 1016 and 1018 Nm/yr is defined by scaling tidal dissipation energy to tectonic events on the Earth's moon. Random catalogs are generated and used to create synthetic continuous noise records through numerical wave propagation in thermodynamically self-consistent models of the interior structure of Europa. Spectral characteristics of the noise are calculated by determining probabilistic power spectral densities of the synthetic records. While the range of seismicity models predicts noise levels that vary by 80 dB, we show that most noise estimates are below the self-noise floor of high-frequency geophones but may be recorded by more sensitive instruments. The largest expected signals exceed background noise by ˜50 dB. Noise records may allow for constraints on interior structure through autocorrelation. Models of seismic noise generated by pressure variations at the base of the ice shell due to turbulent motions in the subsurface ocean may also generate observable seismic noise.

Laboratory Investigation of Noise-Canceling Headphones Utilizing "Mr. Blockhead"

ERIC Educational Resources Information Center

Koser, John

2013-01-01

While I was co-teaching an introductory course in musical acoustics a few years ago, our class investigated several pieces of equipment designed for audio purposes. One piece of such equipment was a pair of noise-canceling headphones. Our students were curious as to how these devices were in eliminating background noise and whether they indeed…

Impact of Noise and Working Memory on Speech Processing in Adults with and without ADHD

ERIC Educational Resources Information Center

Michalek, Anne M. P.

2012-01-01

Auditory processing of speech is influenced by internal (i.e., attention, working memory) and external factors (i.e., background noise, visual information). This study examined the interplay among these factors in individuals with and without ADHD. All participants completed a listening in noise task, two working memory capacity tasks, and two…

Objective Measures of Listening Effort: Effects of Background Noise and Noise Reduction

ERIC Educational Resources Information Center

Sarampalis, Anastasios; Kalluri, Sridhar; Edwards, Brent; Hafter, Ervin

2009-01-01

Purpose: This work is aimed at addressing a seeming contradiction related to the use of noise-reduction (NR) algorithms in hearing aids. The problem is that although some listeners claim a subjective improvement from NR, it has not been shown to improve speech intelligibility, often even making it worse. Method: To address this, the hypothesis…

Urban Rail Noise Abatement Program : A Description

DOT National Transportation Integrated Search

1980-03-01

This report presents the background, current activities, and future plans for the Urban Rail Noise Abatement Program. This program, sponsored by the Office of Technology Development and Deployment of the Urban Mass Transportation Administration (UMTA...

Reading Comprehension in Quiet and in Noise: Effects on Immediate and Delayed Recall in Relation to Tinnitus and High-Frequency Hearing Thresholds.

PubMed

Brännström, K Jonas; Waechter, Sebastian

2018-06-01

A common complaint by people with tinnitus is that they experience that the tinnitus causes attention and concentration problems. Previous studies have examined how tinnitus influences cognitive performance on short and intensive cognitive tasks but without proper control of hearing status. To examine the impact tinnitus and high-frequency hearing thresholds have on reading comprehension in quiet and in background noise. A between-group design with matched control participants. One group of participants with tinnitus (n = 20) and an age and gender matched control group without tinnitus (n = 20) participated. Both groups had normal hearing thresholds (20 dB HL at frequencies 0.125 to 8 kHz). Measurements were made assessing hearing thresholds and immediate and delayed recall using a reading comprehension test in quiet and in noise. All participants completed the Swedish version of the Hospital Anxiety and Depression Scale, and participants with tinnitus also completed the Tinnitus Questionnaire. The groups did not differ in immediate nor delayed recall. Accounting for the effect of age, a significant positive correlation was found between best ear high-frequency pure tone average (HF-PTA; 10000, 12500, and 14000 Hz) and the difference score between immediate and delayed recall in noise. Tinnitus seems to have no effect on immediate and delayed recall in quiet or in background noise when hearing status is controlled for. The detrimental effect of background noise on the processes utilized for efficient encoding into long-term memory is larger in participants with better HF-PTA. More specifically, when reading in noise, participants with better HF-PTA seem to recall less information than participants with poorer HF-PTA. American Academy of Audiology.

Background Oriented Schlieren Implementation in a Jet-Surface Interaction Test

NASA Technical Reports Server (NTRS)

Clem, Michelle M.; Brown, Clifford A.; Fagan, Amy

2013-01-01

Many current and future aircraft designs rely on the wing or other aircraft surfaces to shield the engine noise from observers on the ground. However the available data regarding how a planar surface interacts with a jet to shield and/or enhance the jet noise are currently limited. Therefore, the Jet-Surface Interaction Tests supported by NASA's Fundamental Aeronautics Program's Fixed Wing Project were undertaken to supply experimental data covering a wide range of surface geometries and positions interacting with high-speed jet flows in order to support the development of noise prediction methods. Phase 1 of the Test was conducted in the Aero-Acoustic Propulsion Laboratory at NASA Glenn Research Center and consisted of validating noise prediction schemes for a round nozzle interacting with a planar surface. Phased array data and far-field acoustic data were collected for both the shielded and reflected sides of the surface. Phase 1 results showed that the broadband shock noise was greatly reduced by the surface when the jet was operated at the over-expanded condition, however, it was unclear whether this reduction was due a change in the shock cell structure by the surface. In the present study, Background Oriented Schlieren is implemented in Phase 2 of the Jet-Surface Interaction Tests to investigate whether the planar surface interacts with the high-speed jet ow to change the shock cell structure. Background Oriented Schlieren data are acquired for under-expanded, ideally-expanded, and over-expanded ow regimes for multiple axial and radial positions of the surface at three different plate lengths. These data are analyzed with far-field noise measurements to relate the shock cell structure to the broadband shock noise produced by a jet near a surface.

Characterization of feedback resistors for cryogenic applications

NASA Technical Reports Server (NTRS)

Lakew, B.; Moseley, S. H.; Silverberg, R. F.

1989-01-01

Results are presented on the testing of feedback resistors selected for use in the transimpedance amplifiers (TIAs) in the Diffuse Infrared Background Experiment (DIRBE) to be flown on the NASA's Cosmic Background Explorer satellite planned for a launch in 1989. The resistors without encapsulation were found to be reliable as cryogenic circuit elements. Their resistance is sufficiently high (so that their Johnson noise does not dominate amplifier noise at the signal frequency), and they are sufficiently linear; no correction need to be made for signals up to 1.5 V, the 100,000 signal-to-noise level for the DIRBE, which covers most of the signals expected to be seen on the sky.

Anatomical background and generalized detectability in tomosynthesis and cone-beam CT.

PubMed

Gang, G J; Tward, D J; Lee, J; Siewerdsen, J H

2010-05-01

Anatomical background presents a major impediment to detectability in 2D radiography as well as 3D tomosynthesis and cone-beam CT (CBCT). This article incorporates theoretical and experimental analysis of anatomical background "noise" in cascaded systems analysis of 2D and 3D imaging performance to yield "generalized" metrics of noise-equivalent quanta (NEQ) and detectability index as a function of the orbital extent of the (circular arc) source-detector orbit. A physical phantom was designed based on principles of fractal self-similarity to exhibit power-law spectral density (kappa/Fbeta) comparable to various anatomical sites (e.g., breast and lung). Background power spectra [S(B)(F)] were computed as a function of source-detector orbital extent, including tomosynthesis (approximately 10 degrees -180 degrees) and CBCT (180 degrees + fan to 360 degrees) under two acquisition schemes: (1) Constant angular separation between projections (variable dose) and (2) constant total number of projections (constant dose). The resulting S(B) was incorporated in the generalized NEQ, and detectability index was computed from 3D cascaded systems analysis for a variety of imaging tasks. The phantom yielded power-law spectra within the expected spatial frequency range, quantifying the dependence of clutter magnitude (kappa) and correlation (beta) with increasing tomosynthesis angle. Incorporation of S(B) in the 3D NEQ provided a useful framework for analyzing the tradeoffs among anatomical, quantum, and electronic noise with dose and orbital extent. Distinct implications are posed for breast and chest tomosynthesis imaging system design-applications varying significantly in kappa and beta, and imaging task and, therefore, in optimal selection of orbital extent, number of projections, and dose. For example, low-frequency tasks (e.g., soft-tissue masses or nodules) tend to benefit from larger orbital extent and more fully 3D tomographic imaging, whereas high-frequency tasks (e.g., microcalcifications) require careful, application-specific selection of orbital extent and number of projections to minimize negative effects of quantum and electronic noise. The complex tradeoffs among anatomical background, quantum noise, and electronic noise in projection imaging, tomosynthesis, and CBCT can be described by generalized cascaded systems analysis, providing a useful framework for system design and optimization.

The Acoustic Environment of the NASA Glenn 9- by 15-foot Low-Speed Wind Tunnel

NASA Technical Reports Server (NTRS)

Stephens, David B.

2015-01-01

The 9- by 15-Foot Low Speed Wind Tunnel is an acoustic testing facility with a long history of aircraft propulsion noise research. Due to interest in renovating the facility to support future testing of advanced quiet engine designs, a study was conducted to document the background noise level in the facility and investigate the sources of contaminating noise. The anechoic quality of the facility was also investigated using an interrupted noise method. The present report discusses these aspects of the noise environment in this facility.

Masking of sounds by a background noise--cochlear mechanical correlates.

PubMed

Recio-Spinoso, Alberto; Cooper, Nigel P

2013-05-15

In the search for cochlear correlates of auditory masking by noise stimuli, we recorded basilar membrane (BM) vibrations evoked by either tone or click signals in the presence of varying levels of background noise. The BM vibrations were recorded from basal regions in healthy cochleae of anaesthetized chinchilla and gerbil. Non-linear interactions that could underpin various aspects of psychophysical masking data, including both compression and suppression at the BM level, were observed. The suppression effects, whereby the amplitude of the responses to each stimulus component could be reduced, depended on the relative intensities of the noise and the tones or clicks. Only stimulus components whose frequencies fell inside the non-linear region of the recording site, i.e. around its characteristic frequency (CF), were affected by presentation of the 'suppressing' stimulus (which could be either the tone or the noise). Mutual suppression, the simultaneous reduction of the responses to both tones and noise components, was observed under some conditions, but overall reductions of BM vibration were rarely observed. Moderate- to high-intensity tones suppressed BM responses to low-intensity Gaussian stimuli, including both broadband and narrowband noise. Suppression effects were larger for spectral components of the noise response that were closer to the CF. In this regime, the tone and noise stimuli became the suppressor and probe signals, respectively. This study provides the first detailed observations of cochlear mechanical correlates of the masking effects of noise. Mechanical detection thresholds for tone signals, which were arbitrarily defined using three criteria, are shown to increase in almost direct proportion to the noise level for low and moderately high noise levels, in a manner that resembles the findings of numerous psychophysical observations.

Masking of sounds by a background noise – cochlear mechanical correlates

PubMed Central

Recio-Spinoso, Alberto; Cooper, Nigel P

2013-01-01

In the search for cochlear correlates of auditory masking by noise stimuli, we recorded basilar membrane (BM) vibrations evoked by either tone or click signals in the presence of varying levels of background noise. The BM vibrations were recorded from basal regions in healthy cochleae of anaesthetized chinchilla and gerbil. Non-linear interactions that could underpin various aspects of psychophysical masking data, including both compression and suppression at the BM level, were observed. The suppression effects, whereby the amplitude of the responses to each stimulus component could be reduced, depended on the relative intensities of the noise and the tones or clicks. Only stimulus components whose frequencies fell inside the non-linear region of the recording site, i.e. around its characteristic frequency (CF), were affected by presentation of the ‘suppressing’ stimulus (which could be either the tone or the noise). Mutual suppression, the simultaneous reduction of the responses to both tones and noise components, was observed under some conditions, but overall reductions of BM vibration were rarely observed. Moderate- to high-intensity tones suppressed BM responses to low-intensity Gaussian stimuli, including both broadband and narrowband noise. Suppression effects were larger for spectral components of the noise response that were closer to the CF. In this regime, the tone and noise stimuli became the suppressor and probe signals, respectively. This study provides the first detailed observations of cochlear mechanical correlates of the masking effects of noise. Mechanical detection thresholds for tone signals, which were arbitrarily defined using three criteria, are shown to increase in almost direct proportion to the noise level for low and moderately high noise levels, in a manner that resembles the findings of numerous psychophysical observations. PMID:23478137

Constructing Noise-Invariant Representations of Sound in the Auditory Pathway

PubMed Central

Rabinowitz, Neil C.; Willmore, Ben D. B.; King, Andrew J.; Schnupp, Jan W. H.

2013-01-01

Identifying behaviorally relevant sounds in the presence of background noise is one of the most important and poorly understood challenges faced by the auditory system. An elegant solution to this problem would be for the auditory system to represent sounds in a noise-invariant fashion. Since a major effect of background noise is to alter the statistics of the sounds reaching the ear, noise-invariant representations could be promoted by neurons adapting to stimulus statistics. Here we investigated the extent of neuronal adaptation to the mean and contrast of auditory stimulation as one ascends the auditory pathway. We measured these forms of adaptation by presenting complex synthetic and natural sounds, recording neuronal responses in the inferior colliculus and primary fields of the auditory cortex of anaesthetized ferrets, and comparing these responses with a sophisticated model of the auditory nerve. We find that the strength of both forms of adaptation increases as one ascends the auditory pathway. To investigate whether this adaptation to stimulus statistics contributes to the construction of noise-invariant sound representations, we also presented complex, natural sounds embedded in stationary noise, and used a decoding approach to assess the noise tolerance of the neuronal population code. We find that the code for complex sounds in the periphery is affected more by the addition of noise than the cortical code. We also find that noise tolerance is correlated with adaptation to stimulus statistics, so that populations that show the strongest adaptation to stimulus statistics are also the most noise-tolerant. This suggests that the increase in adaptation to sound statistics from auditory nerve to midbrain to cortex is an important stage in the construction of noise-invariant sound representations in the higher auditory brain. PMID:24265596

Observations and modeling of seismic background noise

USGS Publications Warehouse

Peterson, Jon R.

1993-01-01

The preparation of this report had two purposes. One was to present a catalog of seismic background noise spectra obtained from a worldwide network of seismograph stations. The other purpose was to refine and document models of seismic background noise that have been in use for several years. The second objective was, in fact, the principal reason that this study was initiated and influenced the procedures used in collecting and processing the data.With a single exception, all of the data used in this study were extracted from the digital data archive at the U.S. Geological Survey's Albuquerque Seismological Laboratory (ASL). This archive dates from 1972 when ASL first began deploying digital seismograph systems and collecting and distributing digital data under the sponsorship of the Defense Advanced Research Projects Agency (DARPA). There have been many changes and additions to the global seismograph networks during the past twenty years, but perhaps none as significant as the current deployment of very broadband seismographs by the U.S. Geological Survey (USGS) and the University of California San Diego (UCSD) under the scientific direction of the IRIS consortium. The new data acquisition systems have extended the bandwidth and resolution of seismic recording, and they utilize high-density recording media that permit the continuous recording of broadband data. The data improvements and continuous recording greatly benefit and simplify surveys of seismic background noise.Although there are many other sources of digital data, the ASL archive data were used almost exclusively because of accessibility and because the data systems and their calibration are well documented for the most part. Fortunately, the ASL archive contains high-quality data from other stations in addition to those deployed by the USGS. Included are data from UCSD IRIS/IDA stations, the Regional Seismic Test Network (RSTN) deployed by Sandia National Laboratories (SNL), and the TERRAscope network deployed by the California Institute of Technology in cooperation with other institutions.A map showing the approximate locations of the stations used in this study is provided in Figure 1. One might hope for a better distribution of stations in the southern hemisphere, especially Africa and South America, in order to look for regional variations in seismic noise (apart from the major differences between continental, coastal and island sites). Unfortunately, anyone looking for subtle regional variations in seismic noise is probably going to be disappointed by the spectral data presented in this report because much of the station data appear to be dominated by local disturbances caused by instrumental, environmental, cultural, or surf noise. Better instruments and better instrument siting, or a well-funded field program, will be needed before a global isoseismal noise map can be produced. However, by assembling a composite of background noise from a large network of stations, many of the local station variables are masked, and it is possible to create generalized spectral plots of Earth noise for hypothetical quiet and noisy station sites.

Assessment of capabilities of lidar systems in day-and night-time under different atmospheric and internal-noise conditions

NASA Astrophysics Data System (ADS)

Agishev, Ravil; Comerón, Adolfo

2018-04-01

As an application of the dimensionless parameterization concept proposed earlier for the characterization of lidar systems, the universal assessment of lidar capabilities in day and night conditions is considered. The dimensionless parameters encapsulate the atmospheric conditions, the lidar optical and optoelectronic characteristics, including the photodetector internal noise, and the sky background radiation. Approaches to ensure immunity of the lidar system to external background radiation are discussed.

Electromagnetic Radiation from Corona Discharges.

DTIC Science & Technology

1977-01-25

a 3 MHz bandwidth to cover frequencies below I GHz. Various TWT preamplifiers were used to increase the system gain. R-f energy from the corona point...100 MHz CENTER FREQUENCYr 0.05 mv/div 5 ps/div FIGURE 11. DETECTED I.F SIGNALS RECEIVED FROM A 20’ PIPE IN CORONA 29 the broadband impulsive background...noise at sea, with a secondary objective of measuring background noise at narrower bandwidths on a swept frequency basis. The broadband measurement

Cosmic Infrared Background Fluctuations and Zodiacal Light

NASA Technical Reports Server (NTRS)

Arendt, Richard G.; Kashlinsky, A.; Moseley, S. H.; Mather, J.

2017-01-01

We performed a specific observational test to measure the effect that the zodiacal light can have on measurements of the spatial fluctuations of the near-IR (near-infrared)background. Previous estimates of possible fluctuations caused by zodiacal light have often been extrapolated from observations of the thermal emission at longer wavelengths and low angular resolution or from IRAC (Infrared Array Camera) observations of high-latitude fields where zodiacal light is faint and not strongly varying with time. The new observations analyzed here target the COSMOS (Cosmic Evolution Survey) field at low ecliptic latitude where the zodiacal light intensity varies by factors of approximately 2 over the range of solar elongations at which the field can be observed. We find that the white-noise component of the spatial power spectrum of the background is correlated with the modeled zodiacal light intensity. Roughly half of the measured white noise is correlated with the zodiacal light, but a more detailed interpretation of the white noise is hampered by systematic uncertainties that are evident in the zodiacal light model. At large angular scales (greater than or approximately equal to 100 arcseconds) where excess power above the white noise is observed, we find no correlation of the power with the modeled intensity of the zodiacal light. This test clearly indicates that the large-scale power in the infrared background is not being caused by the zodiacal light.

Particle and Noise Exposure During Highway Maintenance Work

EPA Science Inventory

Background: Exposure to traffic is associated with increased cardiovascular morbidity and mortality. Traffic particles are associated with increased pro‑inflammatory and pro-thrombotic markers as well as altered heart rhythm (Riediker et al. 2004). Occupational noise exposu...

Noise Equally Degrades Central Auditory Processing in 2- and 4-Year-Old Children.

PubMed

Niemitalo-Haapola, Elina; Haapala, Sini; Kujala, Teija; Raappana, Antti; Kujala, Tiia; Jansson-Verkasalo, Eira

2017-08-16

The aim of this study was to investigate developmental and noise-induced changes in central auditory processing indexed by event-related potentials in typically developing children. P1, N2, and N4 responses as well as mismatch negativities (MMNs) were recorded for standard syllables and consonants, frequency, intensity, vowel, and vowel duration changes in silent and noisy conditions in the same 14 children at the ages of 2 and 4 years. The P1 and N2 latencies decreased and the N2, N4, and MMN amplitudes increased with development of the children. The amplitude changes were strongest at frontal electrodes. At both ages, background noise decreased the P1 amplitude, increased the N2 amplitude, and shortened the N4 latency. The noise-induced amplitude changes of P1, N2, and N4 were strongest frontally. Furthermore, background noise degraded the MMN. At both ages, MMN was significantly elicited only by the consonant change, and at the age of 4 years, also by the vowel duration change during noise. Developmental changes indexing maturation of central auditory processing were found from every response studied. Noise degraded sound encoding and echoic memory and impaired auditory discrimination at both ages. The older children were as vulnerable to the impact of noise as the younger children. https://doi.org/10.23641/asha.5233939.

Perception of speech in noise: neural correlates.

PubMed

Song, Judy H; Skoe, Erika; Banai, Karen; Kraus, Nina

2011-09-01

The presence of irrelevant auditory information (other talkers, environmental noises) presents a major challenge to listening to speech. The fundamental frequency (F(0)) of the target speaker is thought to provide an important cue for the extraction of the speaker's voice from background noise, but little is known about the relationship between speech-in-noise (SIN) perceptual ability and neural encoding of the F(0). Motivated by recent findings that music and language experience enhance brainstem representation of sound, we examined the hypothesis that brainstem encoding of the F(0) is diminished to a greater degree by background noise in people with poorer perceptual abilities in noise. To this end, we measured speech-evoked auditory brainstem responses to /da/ in quiet and two multitalker babble conditions (two-talker and six-talker) in native English-speaking young adults who ranged in their ability to perceive and recall SIN. Listeners who were poorer performers on a standardized SIN measure demonstrated greater susceptibility to the degradative effects of noise on the neural encoding of the F(0). Particularly diminished was their phase-locked activity to the fundamental frequency in the portion of the syllable known to be most vulnerable to perceptual disruption (i.e., the formant transition period). Our findings suggest that the subcortical representation of the F(0) in noise contributes to the perception of speech in noisy conditions.

Lombard effect onset times reveal the speed of vocal plasticity in a songbird.

PubMed

Hardman, Samuel I; Zollinger, Sue Anne; Koselj, Klemen; Leitner, Stefan; Marshall, Rupert C; Brumm, Henrik

2017-03-15

Animals that use vocal signals to communicate often compensate for interference and masking from background noise by raising the amplitude of their vocalisations. This response has been termed the Lombard effect. However, despite more than a century of research, little is known how quickly animals can adjust the amplitude of their vocalisations after the onset of noise. The ability to respond quickly to increases in noise levels would allow animals to avoid signal masking and ensure their calls continue to be heard, even if they are interrupted by sudden bursts of high-amplitude noise. We tested how quickly singing male canaries ( Serinus canaria ) exhibit the Lombard effect by exposing them to short playbacks of white noise and measuring the speed of their responses. We show that canaries exhibit the Lombard effect in as little as 300 ms after the onset of noise and are also able to increase the amplitude of their songs mid-song and mid-phrase without pausing. Our results demonstrate high vocal plasticity in this species and suggest that birds are able to adjust the amplitude of their vocalisations very rapidly to ensure they can still be heard even during sudden changes in background noise levels. © 2017. Published by The Company of Biologists Ltd.

Sound levels in modern rodent housing rooms are an uncontrolled environmental variable with fluctuations mainly due to human activities

PubMed Central

Lauer, Amanda M.; May, Bradford J.; Hao, Ziwei Judy; Watson, Julie

2009-01-01

Noise in animal housing facilities is an environmental variable that can affect hearing, behavior and physiology in mice. The authors measured sound levels in two rodent housing rooms (room 1 and room 2) during several periods of 24 h. Room 1, which was subject to heavy personnel traffic, contained ventilated racks and static cages that housed large numbers of mice. Room 2 was accessed by only a few staff members and contained only static cages that housed fewer mice. In both rooms, background sound levels were about 80 dB, and transient noises caused sound levels to temporarily rise 30–40 dB above the baseline level; such peaks occurred frequently during work hours (8:30 AM to 4:30 PM) and infrequently during non-work hours. Noise peaks during work hours in room 1 occurred about two times as often as in room 2 (P = 0.01). Use of changing stations located in the rooms caused background noise to increase by about 10 dB. Loud noise and noise variability were attributed mainly to personnel activity. Attempts to reduce noise should concentrate on controlling sounds produced by in-room activities and experimenter traffic; this may reduce the variability of research outcomes and improve animal welfare. PMID:19384312

Multimodal Communication in a Noisy Environment: A Case Study of the Bornean Rock Frog Staurois parvus

PubMed Central

Grafe, T. Ulmar; Preininger, Doris; Sztatecsny, Marc; Kasah, Rosli; Dehling, J. Maximilian; Proksch, Sebastian; Hödl, Walter

2012-01-01

High background noise is an impediment to signal detection and perception. We report the use of multiple solutions to improve signal perception in the acoustic and visual modality by the Bornean rock frog, Staurois parvus. We discovered that vocal communication was not impaired by continuous abiotic background noise characterised by fast-flowing water. Males modified amplitude, pitch, repetition rate and duration of notes within their advertisement call. The difference in sound pressure between advertisement calls and background noise at the call dominant frequency of 5578 Hz was 8 dB, a difference sufficient for receiver detection. In addition, males used several visual signals to communicate with conspecifics with foot flagging and foot flashing being the most common and conspicuous visual displays, followed by arm waving, upright posture, crouching, and an open-mouth display. We used acoustic playback experiments to test the efficacy-based alerting signal hypothesis of multimodal communication. In support of the alerting hypothesis, we found that acoustic signals and foot flagging are functionally linked with advertisement calling preceding foot flagging. We conclude that S. parvus has solved the problem of continuous broadband low-frequency noise by both modifying its advertisement call in multiple ways and by using numerous visual signals. This is the first example of a frog using multiple acoustic and visual solutions to communicate in an environment characterised by continuous noise. PMID:22655089

Effects of pedagogical ideology on the perceived loudness and noise levels in preschools.

PubMed

Jonsdottir, Valdis; Rantala, Leena M; Oskarsson, Gudmundur Kr; Sala, Eeva

2015-01-01

High activity noise levels that result in detrimental effects on speech communication have been measured in preschools. To find out if different pedagogical ideologies affect the perceived loudness and levels of noise, a questionnaire study inquiring about the experience of loudness and voice symptoms was carried out in Iceland in eight private preschools, called "Hjalli model", and in six public preschools. Noise levels were also measured in the preschools. Background variables (stress level, age, length of working career, education, smoking, and number of children per teacher) were also analyzed in order to determine how much they contributed toward voice symptoms and the experience of noisiness. Results indicate that pedagogical ideology is a significant factor for predicting noise and its consequences. Teachers in the preschool with tighter pedagogical control of discipline (the "Hjalli model") experienced lower activity noise loudness than teachers in the preschool with a more relaxed control of behavior (public preschool). Lower noise levels were also measured in the "Hjalli model" preschool and fewer "Hjalli model" teachers reported voice symptoms. Public preschool teachers experienced more stress than "Hjalli model" teachers and the stress level was, indeed, the background variable that best explained the voice symptoms and the teacher's perception of a noisy environment. Discipline, structure, and organization in the type of activity predicted the activity noise level better than the number of children in the group. Results indicate that pedagogical ideology is a significant factor for predicting self-reported noise and its consequences.

Sonar target enhancement by shrinkage of incoherent wavelet coefficients.

PubMed

Hunter, Alan J; van Vossen, Robbert

2014-01-01

Background reverberation can obscure useful features of the target echo response in broadband low-frequency sonar images, adversely affecting detection and classification performance. This paper describes a resolution and phase-preserving means of separating the target response from the background reverberation noise using a coherence-based wavelet shrinkage method proposed recently for de-noising magnetic resonance images. The algorithm weights the image wavelet coefficients in proportion to their coherence between different looks under the assumption that the target response is more coherent than the background. The algorithm is demonstrated successfully on experimental synthetic aperture sonar data from a broadband low-frequency sonar developed for buried object detection.

Analysis for signal-to-noise ratio of hyper-spectral imaging FTIR interferometer

NASA Astrophysics Data System (ADS)

Li, Xun-niu; Zheng, Wei-jian; Lei, Zheng-gang; Wang, Hai-yang; Fu, Yan-peng

2013-08-01

Signal-to-noise Ratio of hyper-spectral imaging FTIR interferometer system plays a decisive role on the performance of the instrument. It is necessary to analyze them in the development process. Based on the simplified target/background model, the energy transfer model of the LWIR hyper-spectral imaging interferometer has been discussed. The noise equivalent spectral radiance (NESR) and its influencing factors of the interferometer system was analyzed, and the signal-to-noise（SNR） was calculated by using the properties of NESR and incident radiance. In a typical application environment, using standard atmospheric model of USA(1976 COESA) as a background, and set a reasonable target/background temperature difference, and take Michelson spatial modulation Fourier Transform interferometer as an example, the paper had calculated the NESR and the SNR of the interferometer system which using the commercially LWIR cooled FPA and UFPA detector. The system noise sources of the instrument were also analyzed in the paper. The results of those analyses can be used to optimize and pre-estimate the performance of the interferometer system, and analysis the applicable conditions of use different detectors. It has important guiding significance for the LWIR interferometer spectrometer design.

Thunderstorms observed by radio astronomy Explorer 1 over regions of low man made noise

NASA Technical Reports Server (NTRS)

Caruso, J. A.; Herman, J. R.

1974-01-01

Radio Astronomy Explorer (RAE) I observations of thunderstorms over regions of low man-made noise levels are analyzed to assess the satellite's capability for noise source differentiation. The investigation of storms over Australia indicates that RAE can resolve noise generation due to thunderstorms from the general noise background over areas of low man-made noise activity. Noise temperatures observed by RAE over stormy regions are on the average 10DB higher than noise temperatures over the same regions in the absence of thunderstorms. In order to determine the extent of noise contamination due to distant transmitters comprehensive three dimensional computer ray tracings were generated. The results indicate that generally, distant transmitters contribute negligibly to the total noise power, being 30DB or more below contributions arriving from an area immediately below the satellite.

Laboratory Investigation of Noise-Canceling Headphones Utilizing ``Mr. Blockhead''

NASA Astrophysics Data System (ADS)

Koser, John

2013-09-01

While I was co-teaching an introductory course in musical acoustics a few years ago, our class investigated several pieces of equipment designed for audio purposes. One piece of such equipment was a pair of noise-canceling headphones. Our students were curious as to how these devices were in eliminating background noise and whether they indeed block low-frequency sounds as advertised.

The Relationship between Personality Type and Acceptable Noise Levels: A Pilot Study.

PubMed

Franklin, Cliff; Johnson, Laura V; White, Letitia; Franklin, Clay; Smith-Olinde, Laura

2013-01-01

Objectives. This study examined the relationship between acceptable noise level (ANL) and personality. ANL is the difference between a person's most comfortable level for speech and the loudest level of background noise they are willing to accept while listening to speech. Design. Forty young adults with normal hearing participated. ANLs were measured and two personality tests (Big Five Inventory, Myers-Briggs Type Indicator) were administered. Results. The analysis revealed a correlation between ANL and the openness and conscientious personality dimensions from the Big Five Inventory; no correlation emerged between ANL and the Myers-Briggs personality types. Conclusions. Lower ANLs are correlated with full-time hearing aid use and the openness personality dimension; higher ANLs are correlated with part-time or hearing aid nonuse and the conscientious personality dimension. Current data suggest that those more open to new experiences may accept more noise and possibly be good hearing aid candidates, while those more conscientious may accept less noise and reject hearing aids, based on their unwillingness to accept background noise. Knowing something about a person's personality type may help audiologists determine if their patients will likely be good candidates for hearing aids.

The Relationship between Personality Type and Acceptable Noise Levels: A Pilot Study

PubMed Central

Franklin, Cliff; Johnson, Laura V.; Franklin, Clay

2013-01-01

Objectives. This study examined the relationship between acceptable noise level (ANL) and personality. ANL is the difference between a person's most comfortable level for speech and the loudest level of background noise they are willing to accept while listening to speech. Design. Forty young adults with normal hearing participated. ANLs were measured and two personality tests (Big Five Inventory, Myers-Briggs Type Indicator) were administered. Results. The analysis revealed a correlation between ANL and the openness and conscientious personality dimensions from the Big Five Inventory; no correlation emerged between ANL and the Myers-Briggs personality types. Conclusions. Lower ANLs are correlated with full-time hearing aid use and the openness personality dimension; higher ANLs are correlated with part-time or hearing aid nonuse and the conscientious personality dimension. Current data suggest that those more open to new experiences may accept more noise and possibly be good hearing aid candidates, while those more conscientious may accept less noise and reject hearing aids, based on their unwillingness to accept background noise. Knowing something about a person's personality type may help audiologists determine if their patients will likely be good candidates for hearing aids. PMID:24349796

Predicting the performance of linear optical detectors in free space laser communication links

NASA Astrophysics Data System (ADS)

Farrell, Thomas C.

2018-05-01

While the fundamental performance limit for optical communications is set by the quantum nature of light, in practical systems background light, dark current, and thermal noise of the electronics also degrade performance. In this paper, we derive a set of equations predicting the performance of PIN diodes and linear mode avalanche photo diodes (APDs) in the presence of such noise sources. Electrons generated by signal, background, and dark current shot noise are well modeled in PIN diodes as Poissonian statistical processes. In APDs, on the other hand, the amplifying effects of the device result in statistics that are distinctly non-Poissonian. Thermal noise is well modeled as Gaussian. In this paper, we appeal to the central limit theorem and treat both the variability of the signal and the sum of noise sources as Gaussian. Comparison against Monte-Carlo simulation of PIN diode performance (where we do model shot noise with draws from a Poissonian distribution) validates the legitimacy of this approximation. On-off keying, M-ary pulse position, and binary differential phase shift keying modulation are modeled. We conclude with examples showing how the equations may be used in a link budget to estimate the performance of optical links using linear receivers.

Real-time vehicle noise cancellation techniques for gunshot acoustics

NASA Astrophysics Data System (ADS)

Ramos, Antonio L. L.; Holm, Sverre; Gudvangen, Sigmund; Otterlei, Ragnvald

2012-06-01

Acoustical sniper positioning systems rely on the detection and direction-of-arrival (DOA) estimation of the shockwave and the muzzle blast in order to provide an estimate of a potential snipers location. Field tests have shown that detecting and estimating the DOA of the muzzle blast is a rather difficult task in the presence of background noise sources, e.g., vehicle noise, especially in long range detection and absorbing terrains. In our previous work presented in the 2011 edition of this conference we highlight the importance of improving the SNR of the gunshot signals prior to the detection and recognition stages, aiming at lowering the false alarm and miss-detection rates and, thereby, increasing the reliability of the system. This paper reports on real-time noise cancellation techniques, like Spectral Subtraction and Adaptive Filtering, applied to gunshot signals. Our model assumes the background noise as being short-time stationary and uncorrelated to the impulsive gunshot signals. In practice, relatively long periods without signal occur and can be used to estimate the noise spectrum and its first and second order statistics as required in the spectral subtraction and adaptive filtering techniques, respectively. The results presented in this work are supported with extensive simulations based on real data.

[Simulation of speech perception with cochlear implants : Influence of frequency and level of fundamental frequency components with electronic acoustic stimulation].

PubMed

Rader, T; Fastl, H; Baumann, U

2017-03-01

After implantation of cochlear implants with hearing preservation for combined electronic acoustic stimulation (EAS), the residual acoustic hearing ability relays fundamental speech frequency information in the low frequency range. With the help of acoustic simulation of EAS hearing perception the impact of frequency and level fine structure of speech signals can be systematically examined. The aim of this study was to measure the speech reception threshold (SRT) under various noise conditions with acoustic EAS simulation by variation of the frequency and level information of the fundamental frequency f0 of speech. The study was carried out to determine to what extent the SRT is impaired by modification of the f0 fine structure. Using partial tone time pattern analysis an acoustic EAS simulation of the speech material from the Oldenburg sentence test (OLSA) was generated. In addition, determination of the f0 curve of the speech material was conducted. Subsequently, either the parameter frequency or level of f0 was fixed in order to remove one of the two fine contour information of the speech signal. The processed OLSA sentences were used to determine the SRT in background noise under various test conditions. The conditions "f0 fixed frequency" and "f0 fixed level" were tested under two different situations, under "amplitude modulated background noise" and "continuous background noise" conditions. A total of 24 subjects with normal hearing participated in the study. The SRT in background noise for the condition "f0 fixed frequency" was more favorable in continuous noise with 2.7 dB and in modulated noise with 0.8 dB compared to the condition "f0 fixed level" with 3.7 dB and 2.9 dB, respectively. In the simulation of speech perception with cochlear implants and acoustic components, the level information of the fundamental frequency had a stronger impact on speech intelligibility than the frequency information. The method of simulation of transmission of cochlear implants allows investigation of how various parameters influence speech intelligibility in subjects with normal hearing.

Predicting Anthropogenic Noise Contributions to US Waters.

PubMed

Gedamke, Jason; Ferguson, Megan; Harrison, Jolie; Hatch, Leila; Henderson, Laurel; Porter, Michael B; Southall, Brandon L; Van Parijs, Sofie

2016-01-01

To increase understanding of the potential effects of chronic underwater noise in US waters, the National Oceanic and Atmospheric Administration (NOAA) organized two working groups in 2011, collectively called "CetSound," to develop tools to map the density and distribution of cetaceans (CetMap) and predict the contribution of human activities to underwater noise (SoundMap). The SoundMap effort utilized data on density, distribution, acoustic signatures of dominant noise sources, and environmental descriptors to map estimated temporal, spatial, and spectral contributions to background noise. These predicted soundscapes are an initial step toward assessing chronic anthropogenic noise impacts on the ocean's varied acoustic habitats and the animals utilizing them.

Anatomical background noise power spectrum in differential phase contrast breast images

NASA Astrophysics Data System (ADS)

Garrett, John; Ge, Yongshuai; Li, Ke; Chen, Guang-Hong

2015-03-01

In x-ray breast imaging, the anatomical noise background of the breast has a significant impact on the detection of lesions and other features of interest. This anatomical noise is typically characterized by a parameter, β, which describes a power law dependence of anatomical noise on spatial frequency (the shape of the anatomical noise power spectrum). Large values of β have been shown to reduce human detection performance, and in conventional mammography typical values of β are around 3.2. Recently, x-ray differential phase contrast (DPC) and the associated dark field imaging methods have received considerable attention as possible supplements to absorption imaging for breast cancer diagnosis. However, the impact of these additional contrast mechanisms on lesion detection is not yet well understood. In order to better understand the utility of these new methods, we measured the β indices for absorption, DPC, and dark field images in 15 cadaver breast specimens using a benchtop DPC imaging system. We found that the measured β value for absorption was consistent with the literature for mammographic acquisitions (β = 3.61±0.49), but that both DPC and dark field images had much lower values of β (β = 2.54±0.75 for DPC and β = 1.44±0.49 for dark field). In addition, visual inspection showed greatly reduced anatomical background in both DPC and dark field images. These promising results suggest that DPC and dark field imaging may help provide improved lesion detection in breast imaging, particularly for those patients with dense breasts, in whom anatomical noise is a major limiting factor in identifying malignancies.

A retention-time-shift-tolerant background subtraction and noise reduction algorithm (BgS-NoRA) for extraction of drug metabolites in liquid chromatography/mass spectrometry data from biological matrices.

PubMed

Zhu, Peijuan; Ding, Wei; Tong, Wei; Ghosal, Anima; Alton, Kevin; Chowdhury, Swapan

2009-06-01

A retention-time-shift-tolerant background subtraction and noise reduction algorithm (BgS-NoRA) is implemented using the statistical programming language R to remove non-drug-related ion signals from accurate mass liquid chromatography/mass spectrometry (LC/MS) data. The background-subtraction part of the algorithm is similar to a previously published procedure (Zhang H and Yang Y. J. Mass Spectrom. 2008, 43: 1181-1190). The noise reduction algorithm (NoRA) is an add-on feature to help further clean up the residual matrix ion noises after background subtraction. It functions by removing ion signals that are not consistent across many adjacent scans. The effectiveness of BgS-NoRA was examined in biological matrices by spiking blank plasma extract, bile and urine with diclofenac and ibuprofen that have been pre-metabolized by microsomal incubation. Efficient removal of background ions permitted the detection of drug-related ions in in vivo samples (plasma, bile, urine and feces) obtained from rats orally dosed with (14)C-loratadine with minimal interference. Results from these experiments demonstrate that BgS-NoRA is more effective in removing analyte-unrelated ions than background subtraction alone. NoRA is shown to be particularly effective in the early retention region for urine samples and middle retention region for bile samples, where the matrix ion signals still dominate the total ion chromatograms (TICs) after background subtraction. In most cases, the TICs after BgS-NoRA are in excellent qualitative correlation to the radiochromatograms. BgS-NoRA will be a very useful tool in metabolite detection and identification work, especially in first-in-human (FIH) studies and multiple dose toxicology studies where non-radio-labeled drugs are administered. Data from these types of studies are critical to meet the latest FDA guidance on Metabolite in Safety Testing (MIST). Copyright (c) 2009 John Wiley & Sons, Ltd.

Anatomy of the Human Ear/Questions to Ask your Hearing Professional

MedlinePlus

... disorders A severe blow to the head Loud noise Assistive Devices Hearing Aids —Small electronic devices worn ... or without hearing aids to overcome distance, background noise, or poor room acoustics. An example is a ...

A virtual size-variable pinhole for single photon confocal microscopy

NASA Astrophysics Data System (ADS)

Gao, Guangjun; Khoobehi, Bahram

2013-03-01

Pinhole is a critical device in single photon confocal microscopy (SPCM) owning to its ability to block the background noise scattered from back and forth of the focal plane. Without pinhole, the sectioning ability of SPCM will be degraded and many background noise signals will occurred together with useful signals, and sometimes these bad noises can submerge the details that we are interested in. However a pinhole with too small diameter will block both background noises and part of signals and decrease the intensity of the image. Therefore in many cases pinhole size should be selected carefully. Unfortunately because of constrains in mechanics, a pinhole that can change its size continuously, for example from 10 μm to 100 μm, is unavailable. For most commercial confocal microscopies, only several discrete pinhole sizes are provided, such as 10 μm, 30 μm, 60 μm etc. Things will be even harder for some imaging systems which use the input interface of a single mode fiber as the pinhole of SPCM, and then the pinhole size of these systems will be fixed, which far limit the optimization of systems' performance. In this paper, we design a size-variable pinhole setup that can offer a virtual pinhole with its diameter adjustable, which includes a physical pinhole (or single mode fiber) and a fine designed zoom relay (ZR) optical system. The magnification ratio of this ZR can vary smoothly while keeping the conjugation distance unchanged. The aberrations of the ZR are well balanced and diffraction-limited image performance are obtained so that the virtual pinhole can block background scattering noise and pass the in-focus signal effectively and accurately. Simulation results are also provided and discussed.

Untangling the effects of tinnitus and hypersensitivity to sound (hyperacusis) in the gap detection test.

PubMed

Salloum, R H; Sandridge, S; Patton, D J; Stillitano, G; Dawson, G; Niforatos, J; Santiago, L; Kaltenbach, J A

2016-01-01

In recent years, there has been increasing use of the gap detection reflex test to demonstrate induction of tinnitus in animals. Animals with tinnitus show weakened gap detection ability for background noise that matches the pitch of the tinnitus. The usual explanation is that the tinnitus 'fills in the gap'. It has recently been shown, however, that tinnitus is commonly associated with hyperacusis-like enhancements of the acoustic startle response, a change which might potentially alter responses in the gap detection test. We hypothesized that such enhancements could lead to an apparent reduction of gap suppression, resembling that caused by tinnitus, by altering responses to the startle stimulus or the background noise. To test this hypothesis, we compared gap detection abilities in 3 subsets of noise-exposed animals with those in unexposed controls. The results showed that exposed animals demonstrated altered gap detection abilities, but these alterations were sometimes explained as consequences of hyper-responsiveness to either the startle stimulus or to the background noise. Two of the three subsets of animals studied, however, displayed weakened gap detection abilities that could not be explained by enhanced responses to these stimuli or by reduced sound sensitivity or a reduction of temporal processing speed, consistent with the induction of tinnitus. These results demonstrate that not only hearing loss but also changes in sensitivity to background noise or to startle stimuli are potential confounds that, when present, can underlie changes in gap detection irrespective of tinnitus. We discuss how such confounds can be recognized and how they can be avoided. Copyright © 2015 Elsevier B.V. All rights reserved.

On the Uncertainty in Single Molecule Fluorescent Lifetime and Energy Emission Measurements

NASA Technical Reports Server (NTRS)

Brown, Emery N.; Zhang, Zhenhua; McCollom, Alex D.

1996-01-01

Time-correlated single photon counting has recently been combined with mode-locked picosecond pulsed excitation to measure the fluorescent lifetimes and energy emissions of single molecules in a flow stream. Maximum likelihood (ML) and least squares methods agree and are optimal when the number of detected photons is large, however, in single molecule fluorescence experiments the number of detected photons can be less than 20, 67 percent of those can be noise, and the detection time is restricted to 10 nanoseconds. Under the assumption that the photon signal and background noise are two independent inhomogeneous Poisson processes, we derive the exact joint arrival time probability density of the photons collected in a single counting experiment performed in the presence of background noise. The model obviates the need to bin experimental data for analysis, and makes it possible to analyze formally the effect of background noise on the photon detection experiment using both ML or Bayesian methods. For both methods we derive the joint and marginal probability densities of the fluorescent lifetime and fluorescent emission. The ML and Bayesian methods are compared in an analysis of simulated single molecule fluorescence experiments of Rhodamine 110 using different combinations of expected background noise and expected fluorescence emission. While both the ML or Bayesian procedures perform well for analyzing fluorescence emissions, the Bayesian methods provide more realistic measures of uncertainty in the fluorescent lifetimes. The Bayesian methods would be especially useful for measuring uncertainty in fluorescent lifetime estimates in current single molecule flow stream experiments where the expected fluorescence emission is low. Both the ML and Bayesian algorithms can be automated for applications in molecular biology.

Effect of Broadband Nature of Marine Mammal Echolocation Clicks on Click-Based Population Density Estimates

DTIC Science & Technology

2015-09-30

Blainville’s beaked whales (Mesoplodon densirostris), known to be sensitive to sonar sound and therefore of high relevance to the US Navy, and sperm whale...this study were obtained from von Benda-Beckmann et al. (2010) for the beaked whale, and Zimmer (2011) for the sperm whale. 4 For background...Blainville’s beaked whales and sperm whales are commonly present. Analysis of the noise levels on the system indicated that the background noise was system

Noise in any frequency range can enhance information transmission in a sensory neuron

NASA Astrophysics Data System (ADS)

Levin, Jacob E.

1997-05-01

The effect of noise on the neural encoding of broadband signals was investigated in the cricket cercal system, a mechanosensory system sensitive to small near-field air particle disturbances. Known air current stimuli were presented to the cricket through audio speakers in a controlled environment in a variety of background noise conditions. Spike trains from the second layer of neuronal processing, the primary sensory interneurons, were recorded with intracellular Electrodes and the performance of these neurons characterized with the tools of information theory. SNR, mutual information rates, and other measures of encoding accuracy were calculated for single frequency, narrowband, and broadband signals over the entire amplitude sensitivity range of the cells, in the presence of uncorrelated noise background also spanning the cells' frequency and amplitude sensitivity range. Significant enhancements of transmitted information through the addition of external noise were observed regardless of the frequency range of either the signal or noise waveforms, provided both were within the operating range of the cell. Considerable improvements in signal encoding were observed for almost an entire order of magnitude of near-threshold signal amplitudes. This included sinusoidal signals embedded in broadband white noise, broadband signals in broadband noise, and even broadband signals presented with narrowband noise in a completely non-overlapping frequency range. The noise related increases in mutual information rate for broadband signals were as high as 150%, and up to 600% increases in SNR were observed for sinusoidal signals. Additionally, it was shown that the amount of information about the signal carried, on average, by each spike was INCREASED for small signals when presented with noise—implying that added input noise can, in certain situations, actually improve the accuracy of the encoding process itself.

Noise levels in neonatal intensive care unit and use of sound absorbing panel in the isolette.

PubMed

Altuncu, E; Akman, I; Kulekci, S; Akdas, F; Bilgen, H; Ozek, E

2009-07-01

The purposes of this study were to measure the noise level of a busy neonatal intensive care unit (NICU) and to determine the effect of sound absorbing panel (SAP) on the level of noise inside the isolette. The sound pressure levels (SPL) of background noise, baby crying, alarms and closing of isolette's door/portholes were measured by a 2235-Brüel&Kjaer Sound Level Meter. Readings were repeated after applying SAP (3D pyramidal shaped open cell polyurethane foam) to the three lateral walls and ceiling of the isolette. The median SPL of background noise inside the NICU was 56dBA and it decreased to 47dBA inside the isolette. The median SPL of monitor alarms and baby crying inside the isolette were not different than SPL measured under radiant warmer (p>0.05). With SAP, the median SPL of temperature alarm inside the isolette decreased significantly from 82 to 72dBA, monitor alarm from 64 to 56dBA, porthole closing from 81 to 74dBA, and isolette door closing from 80 to 68dBA (p<0.01). There was a significant reduction in the noise produced by baby crying when SAP was used in the isolette (79dBA vs 69dBA, respectively) (p<0.0001). There was also significant attenuation effect of panel on the environmental noise. The noise level in our NICU is significantly above the universally recommended levels. Being inside the isolette protects infants from noise sources produced outside the isolette. However, very high noises are produced inside the isolette as well. Sound absorbing panel can be a simple solution and it attenuated the noise levels inside the isolette.

Background Acoustic Noise Models for the IMS Hydroacoustic Stations

DTIC Science & Technology

2010-09-01

noise models based on data from the 60’s and 70’s ( Urick , 1983). In some ocean basins, noise levels in the monitoring band (1-100 Hz) have risen 15...the 60?s and 70?s ( Urick , 1983). In some ocean basins, noise levels in the monitoring band (1-100 Hz) have risen 15 dB since the 1960?s. To address this...from Urick , 1983. 2010 Monitoring Research Review: Ground-Based Nuclear Explosion Monitoring Technologies 542 To address this issue and provide

Label-free fluorescence strategy for sensitive detection of adenosine triphosphate using a loop DNA probe with low background noise.

PubMed

Lin, Chunshui; Cai, Zhixiong; Wang, Yiru; Zhu, Zhi; Yang, Chaoyong James; Chen, Xi

2014-07-15

A simple, rapid, label-free, and ultrasensitive fluorescence strategy for adenosine triphosphate (ATP) detection was developed using a loop DNA probe with low background noise. In this strategy, a loop DNA probe, which is the substrate for both ligation and digestion enzyme reaction, was designed. SYBR green I (SG I), a double-stranded specific dye, was applied for the readout fluorescence signal. Exonuclease I (Exo I) and exonuclease III (Exo III), sequence-independent nucleases, were selected to digest the loop DNA probe in order to minimize the background fluorescence signal. As a result, in the absence of ATP, the loop DNA was completely digested by Exo I and Exo III, leading to low background fluorescence owing to the weak electrostatic interaction between SG I and mononucleotides. On the other hand, ATP induced the ligation of the nicking site, and the sealed loop DNA resisted the digestion of Exo I and ExoIII, resulting in a remarkable increase of fluorescence response. Upon background noise reduction, the sensitivity of the ATP determination was improved significantly, and the detection limitation was found to be 1.2 pM, which is much lower than that in almost all the previously reported methods. This strategy has promise for wide application in the determination of ATP.

Sensory-Cognitive Interaction in the Neural Encoding of Speech in Noise: A Review

PubMed Central

Anderson, Samira; Kraus, Nina

2011-01-01

Background Speech-in-noise (SIN) perception is one of the most complex tasks faced by listeners on a daily basis. Although listening in noise presents challenges for all listeners, background noise inordinately affects speech perception in older adults and in children with learning disabilities. Hearing thresholds are an important factor in SIN perception, but they are not the only factor. For successful comprehension, the listener must perceive and attend to relevant speech features, such as the pitch, timing, and timbre of the target speaker’s voice. Here, we review recent studies linking SIN and brainstem processing of speech sounds. Purpose To review recent work that has examined the ability of the auditory brainstem response to complex sounds (cABR), which reflects the nervous system’s transcription of pitch, timing, and timbre, to be used as an objective neural index for hearing-in-noise abilities. Study Sample We examined speech-evoked brainstem responses in a variety of populations, including children who are typically developing, children with language-based learning impairment, young adults, older adults, and auditory experts (i.e., musicians). Data Collection and Analysis In a number of studies, we recorded brainstem responses in quiet and babble noise conditions to the speech syllable /da/ in all age groups, as well as in a variable condition in children in which /da/ was presented in the context of seven other speech sounds. We also measured speech-in-noise perception using the Hearing-in-Noise Test (HINT) and the Quick Speech-in-Noise Test (QuickSIN). Results Children and adults with poor SIN perception have deficits in the subcortical spectrotemporal representation of speech, including low-frequency spectral magnitudes and the timing of transient response peaks. Furthermore, auditory expertise, as engendered by musical training, provides both behavioral and neural advantages for processing speech in noise. Conclusions These results have implications for future assessment and management strategies for young and old populations whose primary complaint is difficulty hearing in background noise. The cABR provides a clinically applicable metric for objective assessment of individuals with SIN deficits, for determination of the biologic nature of disorders affecting SIN perception, for evaluation of appropriate hearing aid algorithms, and for monitoring the efficacy of auditory remediation and training. PMID:21241645

Immersive audiomotor game play enhances neural and perceptual salience of weak signals in noise

PubMed Central

Whitton, Jonathon P.; Hancock, Kenneth E.; Polley, Daniel B.

2014-01-01

All sensory systems face the fundamental challenge of encoding weak signals in noisy backgrounds. Although discrimination abilities can improve with practice, these benefits rarely generalize to untrained stimulus dimensions. Inspired by recent findings that action video game training can impart a broader spectrum of benefits than traditional perceptual learning paradigms, we trained adult humans and mice in an immersive audio game that challenged them to forage for hidden auditory targets in a 2D soundscape. Both species learned to modulate their angular search vectors and target approach velocities based on real-time changes in the level of a weak tone embedded in broadband noise. In humans, mastery of this tone in noise task generalized to an improved ability to comprehend spoken sentences in speech babble noise. Neural plasticity in the auditory cortex of trained mice supported improved decoding of low-intensity sounds at the training frequency and an enhanced resistance to interference from background masking noise. These findings highlight the potential to improve the neural and perceptual salience of degraded sensory stimuli through immersive computerized games. PMID:24927596

Immersive audiomotor game play enhances neural and perceptual salience of weak signals in noise.

PubMed

Whitton, Jonathon P; Hancock, Kenneth E; Polley, Daniel B

2014-06-24

All sensory systems face the fundamental challenge of encoding weak signals in noisy backgrounds. Although discrimination abilities can improve with practice, these benefits rarely generalize to untrained stimulus dimensions. Inspired by recent findings that action video game training can impart a broader spectrum of benefits than traditional perceptual learning paradigms, we trained adult humans and mice in an immersive audio game that challenged them to forage for hidden auditory targets in a 2D soundscape. Both species learned to modulate their angular search vectors and target approach velocities based on real-time changes in the level of a weak tone embedded in broadband noise. In humans, mastery of this tone in noise task generalized to an improved ability to comprehend spoken sentences in speech babble noise. Neural plasticity in the auditory cortex of trained mice supported improved decoding of low-intensity sounds at the training frequency and an enhanced resistance to interference from background masking noise. These findings highlight the potential to improve the neural and perceptual salience of degraded sensory stimuli through immersive computerized games.

Regulation of Cortical Dynamic Range by Background Synaptic Noise and Feedforward Inhibition.

PubMed

Khubieh, Ayah; Ratté, Stéphanie; Lankarany, Milad; Prescott, Steven A

2016-08-01

The cortex encodes a broad range of inputs. This breadth of operation requires sensitivity to weak inputs yet non-saturating responses to strong inputs. If individual pyramidal neurons were to have a narrow dynamic range, as previously claimed, then staggered all-or-none recruitment of those neurons would be necessary for the population to achieve a broad dynamic range. Contrary to this explanation, we show here through dynamic clamp experiments in vitro and computer simulations that pyramidal neurons have a broad dynamic range under the noisy conditions that exist in the intact brain due to background synaptic input. Feedforward inhibition capitalizes on those noise effects to control neuronal gain and thereby regulates the population dynamic range. Importantly, noise allows neurons to be recruited gradually and occludes the staggered recruitment previously attributed to heterogeneous excitation. Feedforward inhibition protects spike timing against the disruptive effects of noise, meaning noise can enable the gain control required for rate coding without compromising the precise spike timing required for temporal coding. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Comparison of fluorescence rejection methods of baseline correction and shifted excitation Raman difference spectroscopy

NASA Astrophysics Data System (ADS)

Cai, Zhijian; Zou, Wenlong; Wu, Jianhong

2017-10-01

Raman spectroscopy has been extensively used in biochemical tests, explosive detection, food additive and environmental pollutants. However, fluorescence disturbance brings a big trouble to the applications of portable Raman spectrometer. Currently, baseline correction and shifted-excitation Raman difference spectroscopy (SERDS) methods are the most prevailing fluorescence suppressing methods. In this paper, we compared the performances of baseline correction and SERDS methods, experimentally and simulatively. Through the comparison, it demonstrates that the baseline correction can get acceptable fluorescence-removed Raman spectrum if the original Raman signal has good signal-to-noise ratio, but it cannot recover the small Raman signals out of large noise background. By using SERDS method, the Raman signals, even very weak compared to fluorescence intensity and noise level, can be clearly extracted, and the fluorescence background can be completely rejected. The Raman spectrum recovered by SERDS has good signal to noise ratio. It's proved that baseline correction is more suitable for large bench-top Raman system with better quality or signal-to-noise ratio, while the SERDS method is more suitable for noisy devices, especially the portable Raman spectrometers.

Radiation noise in a high sensitivity star sensor

NASA Technical Reports Server (NTRS)

Parkinson, J. B.; Gordon, E.

1972-01-01

An extremely accurate attitude determination was developed for space applications. This system uses a high sensitivity star sensor in which the photomultiplier tube is subject to noise generated by space radiations. The space radiation induced noise arises from trapped electrons, solar protons and other ionizing radiations, as well as from dim star background. The solar activity and hence the electron and proton environments are predicted through the end of the twentieth century. The available data for the response of the phototube to proton, electron, gamma ray, and bremsstrahlung radiations are reviewed and new experimental data is presented. A simulation was developed which represents the characteristics of the effect of radiations on the star sensor, including the non-stationarity of the backgrounds.

33 CFR 86.05 - Sound signal intensity and range of audibility.

Code of Federal Regulations, 2010 CFR

2010-07-01

... average background noise level at the listening posts (taken to be 68 dB in the octave band centered on... regarded as typical but under conditions of strong wind or high ambient noise level at the listening post...

Frequency response of the USGS short period telemetered seismic system and its suitability for network studies of local earthquakes

USGS Publications Warehouse

Eaton, Jerry P.

1977-01-01

The USGS telemetered seismic system was intended primarily to record small to moderate earthquakes (magnitude 0 to 4) at distances of a few km to several hundred km. Its frequency response is such that the recorded background noise at a moderately quite Coast Range site has a relatively flat 'record' spectrum from about 1/3 Hz to about 20 Hz. With the system magnification set so that the background noise is clearly recorded (about 1 mm peak-to-peak) one can anticipate that any seismic signal that exceeds background noise appreciably in this spectral region will be large enough to be seen on the seismogram. This response represents the highest sensitivity and broadest bandwidth that we were able to attain with a 1-Hz seismometer, a simple amplifier VCO employing very low-power integrated circuits, and an 8-channel constant-bandwidth FM subcarrier multiplex system for use with commercial voice-grade phone lines.

Virtual wayfinding using simulated prosthetic vision in gaze-locked viewing.

PubMed

Wang, Lin; Yang, Liancheng; Dagnelie, Gislin

2008-11-01

To assess virtual maze navigation performance with simulated prosthetic vision in gaze-locked viewing, under the conditions of varying luminance contrast, background noise, and phosphene dropout. Four normally sighted subjects performed virtual maze navigation using simulated prosthetic vision in gaze-locked viewing, under five conditions of luminance contrast, background noise, and phosphene dropout. Navigation performance was measured as the time required to traverse a 10-room maze using a game controller, and the number of errors made during the trip. Navigation performance time (1) became stable after 6 to 10 trials, (2) remained similar on average at luminance contrast of 68% and 16% but had greater variation at 16%, (3) was not significantly affected by background noise, and (4) increased by 40% when 30% of phosphenes were removed. Navigation performance time and number of errors were significantly and positively correlated. Assuming that the simulated gaze-locked viewing conditions are extended to implant wearers, such prosthetic vision can be helpful for wayfinding in simple mobility tasks, though phosphene dropout may interfere with performance.

Lenses in the forest: cross correlation of the Lyman-alpha flux with cosmic microwave background lensing.

PubMed

Vallinotto, Alberto; Das, Sudeep; Spergel, David N; Viel, Matteo

2009-08-28

We present a theoretical estimate for a new observable: the cross correlation between the Lyman-alpha flux fluctuations in quasar spectra and the convergence of the cosmic microwave background as measured along the same line of sight. As a first step toward the assessment of its detectability, we estimate the signal-to-noise ratio using linear theory. Although the signal-to-noise is small for a single line of sight and peaks at somewhat smaller redshifts than those probed by the Lyman-alpha forest, we estimate a total signal-to-noise of 9 for cross correlating quasar spectra of SDSS-III with Planck and 20 for cross correlating with a future polarization based cosmic microwave background experiment. The detection of this effect would be a direct measure of the neutral hydrogen-matter cross correlation and could provide important information on the growth of structures at large scales in a redshift range which is still poorly probed.

Background noise analysis in urban airport surroundings of Brazilian cities, Congonhas Airport, São Paulo.

PubMed

Scatolini, Fabio; Alves, Cláudio Jorge Pinto

2016-12-22

To perform a quantitative analysis of the background noise at Congonhas Airport surroundings based on large sampling and measurements with no interruption. Measuring sites were chosen from 62 and 72 DNL (day-night-level) noise contours, in urban sites compatible with residential use. Fifteen sites were monitored for at least 168 hours without interruption or seven consecutive days. Data compilation was based on cross-reference between noise measurements and air traffic control records, and results were validated by airport meteorological reports. Preliminary diagnoses were established using the standard NBR-13368. Background noise values were calculated based on the Sound Exposure Level (SEL). Statistic parameters were calculated in one-hour intervals. Only four of the fifteen sites assessed presented aircraft operations as a clear cause for the noise annoyance. Even so, it is possible to detect background noise levels above regulation limits during periods of low airport activity or when it closes at night. All the sites monitored showed background noise levels above regulation limits between 7:00 and 21:00. In the intervals between 6:00-6:59 and 21:00-22:59 the noise data, when analyzed with the current airport operational characteristics, still allow the development of additional mitigating measures. Avaliar quantitativamente o ruído de fundo no entorno do aeroporto de Congonhas, com base em ampla amostragem e medições sem interrupção. Locais de medição escolhidos a partir de curvas de ruído de 62 e 72 LDN (day-night level), em equipamentos urbanos de uso compatível com o residencial. Quinze locais foram avaliados por mais de 168 horas consecutivas cada um (sete dias). A compilação baseou-se em cruzamentos de dados do controle de tráfego aéreo e os resultados foram validados por meio de relatórios meteorológicos do aeroporto. Diagnósticos preliminares foram estabelecidos utilizando a NBR-13368. O ruído de fundo foi calculado com base no Sound Exposure Level (SEL). Os parâmetros estatísticos foram calculados em intervalos de uma hora. Apenas quatro dos 15 locais avaliados apresentaram clara contribuição da operação de aeronaves no incômodo. Mesmo assim, é possível identificar ruído de fundo acima do regulamentar durante os períodos de baixa atividade ou de fechamento do aeroporto durante a noite. Todos os locais avaliados apresentaram ruído de fundo acima do regulamentar entre 7:00h e 21:00h. Nos intervalos entre 6:00h-6:59h e 21:00h-22:59h, os dados de monitoramento, quando analisados em conjunto com as atuais características operacionais do aeroporto, ainda possibilitam a elaboração de medidas mitigadoras adicionais.

Ageing without hearing loss or cognitive impairment causes a decrease in speech intelligibility only in informational maskers.

PubMed

Rajan, R; Cainer, K E

2008-06-23

In most everyday settings, speech is heard in the presence of competing sounds and understanding speech requires skills in auditory streaming and segregation, followed by identification and recognition, of the attended signals. Ageing leads to difficulties in understanding speech in noisy backgrounds. In addition to age-related changes in hearing-related factors, cognitive factors also play a role but it is unclear to what extent these are generalized or modality-specific cognitive factors. We examined how ageing in normal-hearing decade age cohorts from 20 to 69 years affected discrimination of open-set speech in background noise. We used two types of sentences of similar structural and linguistic characteristics but different masking levels (i.e. differences in signal-to-noise ratios required for detection of sentences in a standard masker) so as to vary sentence demand, and two background maskers (one causing purely energetic masking effects and the other causing energetic and informational masking) to vary load conditions. There was a decline in performance (measured as speech reception thresholds for perception of sentences in noise) in the oldest cohort for both types of sentences, but only in the presence of the more demanding informational masker. We interpret these results to indicate a modality-specific decline in cognitive processing, likely a decrease in the ability to use acoustic and phonetic cues efficiently to segregate speech from background noise, in subjects aged >60.

Classroom Listening Conditions in Indian Primary Schools: A Survey of Four Schools

PubMed Central

Sundaravadhanan, Gayathri; Selvarajan, Heramba G.; McPherson, Bradley

2017-01-01

Introduction: Background noise affects the listening environment inside classrooms, especially for younger children. High background noise level adversely affects not only student speech perception but also teacher vocal hygiene. The current study aimed to give an overview of the classroom listening conditions in selected government primary schools in India. Materials and Methods: Noise measurements were taken in 23 classrooms of four government primary schools in southern India, using a type 2 sound level meter. In each classroom measurements were taken in occupied and unoccupied conditions. Teacher voice level was measured in the same classrooms. In addition, the classroom acoustical conditions were observed and the reverberation time for each classroom was calculated. Results: The mean occupied noise level was 62.1 dBA and 65.6 dBC, and the mean unoccupied level was 62.2 dBA and 65 dBC. The mean unamplified teacher speech-to-noise ratio was 10.6 dBA. Both the occupied and unoccupied noise levels exceeded national and international recommended levels and the teacher speech-to-noise ratio was also found to be inadequate in most classrooms. The estimated reverberation time in all classrooms was greater than 2.6 seconds, which is almost double the duration of accepted standards. In addition, observation of classrooms revealed insufficient acoustical treatment to effectively reduce internal and external noise and minimize reverberation. Conclusion: The results of this study point out the need to improve the listening environment for children in government primary schools in India. PMID:28164937

Classroom Listening Conditions in Indian Primary Schools: A Survey of Four Schools.

PubMed

Sundaravadhanan, Gayathri; Selvarajan, Heramba G; McPherson, Bradley

2017-01-01

Background noise affects the listening environment inside classrooms, especially for younger children. High background noise level adversely affects not only student speech perception but also teacher vocal hygiene. The current study aimed to give an overview of the classroom listening conditions in selected government primary schools in India. Noise measurements were taken in 23 classrooms of four government primary schools in southern India, using a type 2 sound level meter. In each classroom measurements were taken in occupied and unoccupied conditions. Teacher voice level was measured in the same classrooms. In addition, the classroom acoustical conditions were observed and the reverberation time for each classroom was calculated. The mean occupied noise level was 62.1 dBA and 65.6 dBC, and the mean unoccupied level was 62.2 dBA and 65 dBC. The mean unamplified teacher speech-to-noise ratio was 10.6 dBA. Both the occupied and unoccupied noise levels exceeded national and international recommended levels and the teacher speech-to-noise ratio was also found to be inadequate in most classrooms. The estimated reverberation time in all classrooms was greater than 2.6 seconds, which is almost double the duration of accepted standards. In addition, observation of classrooms revealed insufficient acoustical treatment to effectively reduce internal and external noise and minimize reverberation. The results of this study point out the need to improve the listening environment for children in government primary schools in India.

Effects of pedagogical ideology on the perceived loudness and noise levels in preschools

PubMed Central

Jonsdottir, Valdis; Rantala, Leena M.; Oskarsson, Gudmundur Kr.; Sala, Eeva

2015-01-01

High activity noise levels that result in detrimental effects on speech communication have been measured in preschools. To find out if different pedagogical ideologies affect the perceived loudness and levels of noise, a questionnaire study inquiring about the experience of loudness and voice symptoms was carried out in Iceland in eight private preschools, called “Hjalli model”, and in six public preschools. Noise levels were also measured in the preschools. Background variables (stress level, age, length of working career, education, smoking, and number of children per teacher) were also analyzed in order to determine how much they contributed toward voice symptoms and the experience of noisiness. Results indicate that pedagogical ideology is a significant factor for predicting noise and its consequences. Teachers in the preschool with tighter pedagogical control of discipline (the “Hjalli model”) experienced lower activity noise loudness than teachers in the preschool with a more relaxed control of behavior (public preschool). Lower noise levels were also measured in the “Hjalli model” preschool and fewer “Hjalli model” teachers reported voice symptoms. Public preschool teachers experienced more stress than “Hjalli model” teachers and the stress level was, indeed, the background variable that best explained the voice symptoms and the teacher's perception of a noisy environment. Discipline, structure, and organization in the type of activity predicted the activity noise level better than the number of children in the group. Results indicate that pedagogical ideology is a significant factor for predicting self-reported noise and its consequences. PMID:26356370

Low-frequency noise measurements: applications, methodologies and instrumentation

NASA Astrophysics Data System (ADS)

Ciofi, Carmine; Neri, Bruno

2003-05-01

Low frequency noise measurements (f<10Hz) are a powerful tool for the investigation of the quality and reliability of electron devices and material. In most cases, however, the application of this technique is made quite difficult both because of the effect of external interferences (temperature fluctuations, EMI, mechanical vibrations, etc.) and because of the high level of flicker noise of the commercial instrumentation. In this paper the most remarkable results we obtained by using low frequency noise measurements for the characterization of the reliability of VLSI metallic interconnections and thin oxides are resumed. Moreover, we discuss the effects of the several sources of noise and interferences which contribute to reduce the sensitivity of the measurement chain. In particular, we demonstrate that by means of a proper design, dedicated instrumentation can be built which allows for a considerable reduction of the overall background noise. Examples will be given with reference to voltage and transresistance amplifiers (both AC and DC coupled), to programmable biasing systems (both current and voltage sources), to thermal stabilization systems and to data acquisition systems. Finally, we will discuss methods which may allow, in proper conditions, to accurately measure noise levels well below the background noise of the input preamplifiers coupled to the device under test. As the systems we discuss are characterized by moderate complexity and employ components readily available on the market, we trust that this paper may also serve as a simple guideline to anyone interested in exploiting the possibility of using very low frequency noise measurements by building his own instrumentation.

The Majorana Low-noise Low-background Front-end Electronics

NASA Astrophysics Data System (ADS)

Abgrall, N.; Aguayo, E.; Avignone, F. T.; Barabash, A. S.; Bertrand, F. E.; Boswell, M.; Brudanin, V.; Busch, M.; Byram, D.; Caldwell, A. S.; Chan, Y.-D.; Christofferson, C. D.; Combs, D. C.; Cuesta, C.; Detwiler, J. A.; Doe, P. J.; Efremenko, Yu.; Egorov, V.; Ejiri, H.; Elliott, S. R.; Fast, J. E.; Finnerty, P.; Fraenkle, F. M.; Galindo-Uribarri, A.; Giovanetti, G. K.; Goett, J.; Green, M. P.; Gruszko, J.; Guiseppe, V. E.; Gusev, K.; Hallin, A. L.; Hazama, R.; Hegai, A.; Henning, R.; Hoppe, E. W.; Howard, S.; Howe, M. A.; Keeter, K. J.; Kidd, M. F.; Kochetov, O.; Konovalov, S. I.; Kouzes, R. T.; LaFerriere, B. D.; Leon, J.; Leviner, L. E.; Loach, J. C.; MacMullin, J.; MacMullin, S.; Martin, R. D.; Meijer, S.; Mertens, S.; Nomachi, M.; Orrell, J. L.; O'Shaughnessy, C.; Overman, N. R.; Phillips, D. G.; Poon, A. W. P.; Pushkin, K.; Radford, D. C.; Rager, J.; Rielage, K.; Robertson, R. G. H.; Romero-Romero, E.; Ronquest, M. C.; Schubert, A. G.; Shanks, B.; Shima, T.; Shirchenko, M.; Snavely, K. J.; Snyder, N.; Suriano, A. M.; Thompson, J.; Timkin, V.; Tornow, W.; Trimble, J. E.; Varner, R. L.; Vasilyev, S.; Vetter, K.; Vorren, K.; White, B. R.; Wilkerson, J. F.; Wiseman, C.; Xu, W.; Yakushev, E.; Young, A. R.; Yu, C.-H.; Yumatov, V.

The MAJORANA DEMONSTRATOR will search for the neutrinoless double beta decay (ββ(0ν)) of the isotope 76Ge with a mixed array of enriched and natural germanium detectors. In view of the next generation of tonne-scale germanium-based ββ(0ν)-decay searches, a major goal of the MAJORANA DEMONSTRATOR is to demonstrate a path forward to achieving a background rate at or below 1 cnt/(ROI-t-y) in the 4 keV region of interest (ROI) around the 2039-keV Q-value of the 76Ge ββ(0ν)-decay. Such a requirement on the background level significantly constrains the design of the readout electronics, which is further driven by noise and energy resolution performances. We present here the low-noise low- background front-end electronics developed for the low-capacitance p-type point contact (P-PC) germanium detectors of the MAJORANA DEMONSTRATOR. This resistive-feedback front-end, specifically designed to have low mass, is fabricated on a radioassayed fused-silica substrate where the feedback resistor consists of a sputtered thin film of high purity amorphous germanium and the feedback capacitor is based on the capacitance between gold conductive traces.

Stochastic Background from Coalescences of Neutron Star-Neutron Star Binaries

NASA Astrophysics Data System (ADS)

Regimbau, T.; de Freitas Pacheco, J. A.

2006-05-01

In this work, numerical simulations were used to investigate the gravitational stochastic background produced by coalescences of double neutron star systems occurring up to z~5. The cosmic coalescence rate was derived from Monte Carlo methods using the probability distributions for massive binaries to form and for a coalescence to occur in a given redshift. A truly continuous background is produced by events located only beyond the critical redshift z*=0.23. Events occurring in the redshift interval 0.027

Initial Assessment of Acoustic Source Visibility with a 24-Element Microphone Array in the Arnold Engineering Development Center 80- by 120-Foot Wind Tunnel at NASA Ames Research Center

NASA Technical Reports Server (NTRS)

Horne, William C.

2011-01-01

Measurements of background noise were recently obtained with a 24-element phased microphone array in the test section of the Arnold Engineering Development Center 80- by120-Foot Wind Tunnel at speeds of 50 to 100 knots (27.5 to 51.4 m/s). The array was mounted in an aerodynamic fairing positioned with array center 1.2m from the floor and 16 m from the tunnel centerline, The array plate was mounted flush with the fairing surface as well as recessed in. (1.27 cm) behind a porous Kevlar screen. Wind-off speaker measurements were also acquired every 15 on a 10 m semicircular arc to assess directional resolution of the array with various processing algorithms, and to estimate minimum detectable source strengths for future wind tunnel aeroacoustic studies. The dominant background noise of the facility is from the six drive fans downstream of the test section and first set of turning vanes. Directional array response and processing methods such as background-noise cross-spectral-matrix subtraction suggest that sources 10-15 dB weaker than the background can be detected.

The Majorana low-noise low-background front-end electronics

DOE PAGES

Abgrall, N.; Aguayo, E.; Avignone, III, F. T.; ...

2015-03-24

The Majorana Demonstrator will search for the neutrinoless double beta decay (ββ(0ν)) of the isotope ⁷⁶Ge with a mixed array of enriched and natural germanium detectors. In view of the next generation of tonne-scale germanium-based ββ(0ν)-decay searches, a major goal of the Majorana Demonstrator is to demonstrate a path forward to achieving a background rate at or below 1 cnt/(ROI-t-y) in the 4 keV region of interest (ROI) around the 2039-keV Q-value of the ⁷⁶Ge ββ(0ν)-decay. Such a requirement on the background level significantly constrains the design of the readout electronics, which is further driven by noise and energy resolutionmore » performances. We present here the low-noise low-background front-end electronics developed for the low-capacitance p-type point contact (P-PC) germanium detectors of the Majorana Demonstrator. This resistive-feedback front-end, specifically designed to have low mass, is fabricated on a radioassayed fused-silica substrate where the feedback resistor consists of a sputtered thin film of high purity amorphous germanium and the feedback capacitor is based on the capacitance between gold conductive traces.« less

Influence of background size, luminance and eccentricity on different adaptation mechanisms

PubMed Central

Gloriani, Alejandro H.; Matesanz, Beatriz M.; Barrionuevo, Pablo A.; Arranz, Isabel; Issolio, Luis; Mar, Santiago; Aparicio, Juan A.

2016-01-01

Mechanisms of light adaptation have been traditionally explained with reference to psychophysical experimentation. However, the neural substrata involved in those mechanisms remain to be elucidated. Our study analyzed links between psychophysical measurements and retinal physiological evidence with consideration for the phenomena of rod-cone interactions, photon noise, and spatial summation. Threshold test luminances were obtained with steady background fields at mesopic and photopic light levels (i.e., 0.06–110 cd/m2) for retinal eccentricities from 0° to 15° using three combinations of background/test field sizes (i.e., 10°/2°, 10°/0.45°, and 1°/0.45°). A two-channel Maxwellian view optical system was employed to eliminate pupil effects on the measured thresholds. A model based on visual mechanisms that were described in the literature was optimized to fit the measured luminance thresholds in all experimental conditions. Our results can be described by a combination of visual mechanisms. We determined how spatial summation changed with eccentricity and how subtractive adaptation changed with eccentricity and background field size. According to our model, photon noise plays a significant role to explain contrast detection thresholds measured with the 1/0.45° background/test size combination at mesopic luminances and at off-axis eccentricities. In these conditions, our data reflect the presence of rod-cone interaction for eccentricities between 6° and 9° and luminances between 0.6 and 5 cd/m2. In spite of the increasing noise effects with eccentricity, results also show that the visual system tends to maintain a constant signal-to-noise ratio in the off-axis detection task over the whole mesopic range. PMID:27210038

Influence of background size, luminance and eccentricity on different adaptation mechanisms.

PubMed

Gloriani, Alejandro H; Matesanz, Beatriz M; Barrionuevo, Pablo A; Arranz, Isabel; Issolio, Luis; Mar, Santiago; Aparicio, Juan A

2016-08-01

Mechanisms of light adaptation have been traditionally explained with reference to psychophysical experimentation. However, the neural substrata involved in those mechanisms remain to be elucidated. Our study analyzed links between psychophysical measurements and retinal physiological evidence with consideration for the phenomena of rod-cone interactions, photon noise, and spatial summation. Threshold test luminances were obtained with steady background fields at mesopic and photopic light levels (i.e., 0.06-110cd/m(2)) for retinal eccentricities from 0° to 15° using three combinations of background/test field sizes (i.e., 10°/2°, 10°/0.45°, and 1°/0.45°). A two-channel Maxwellian view optical system was employed to eliminate pupil effects on the measured thresholds. A model based on visual mechanisms that were described in the literature was optimized to fit the measured luminance thresholds in all experimental conditions. Our results can be described by a combination of visual mechanisms. We determined how spatial summation changed with eccentricity and how subtractive adaptation changed with eccentricity and background field size. According to our model, photon noise plays a significant role to explain contrast detection thresholds measured with the 1/0.45° background/test size combination at mesopic luminances and at off-axis eccentricities. In these conditions, our data reflect the presence of rod-cone interaction for eccentricities between 6° and 9° and luminances between 0.6 and 5cd/m(2). In spite of the increasing noise effects with eccentricity, results also show that the visual system tends to maintain a constant signal-to-noise ratio in the off-axis detection task over the whole mesopic range. Copyright © 2016 Elsevier Ltd. All rights reserved.

Study of improving signal-noise ratio for fluorescence channel

NASA Astrophysics Data System (ADS)

Wang, Guoqing; Li, Xin; Lou, Yue; Chen, Dong; Zhao, Xin; Wang, Ran; Yan, Debao; Zhao, Qi

2017-10-01

Laser-induced fluorescence(LIFS), which is one of most effective discrimination methods to identify the material at the molecular level by inducing fluorescence spectrum, has been popularized for its fast and accurate probe's results. According to the research, violet laser or ultraviolet laser is always used as excitation light source. While, There is no atmospheric window for violet laser and ultraviolet laser, causing laser attenuation along its propagation path. What's worse, as the laser reaching sample, part of the light is reflected. That is, excitation laser really react on sample to produce fluorescence is very poor, leading to weak fluorescence mingled with the background light collected by LIFS' processing unit, when it used outdoor. In order to spread LIFS to remote probing under the complex background, study of improving signal-noise ratio for fluorescence channel is a meaningful work. Enhancing the fluorescence intensity and inhibiting background light both can improve fluorescence' signal-noise ratio. In this article, three different approaches of inhibiting background light are discussed to improve the signal-noise ratio of LIFS. The first method is increasing fluorescence excitation area in the proportion of LIFS' collecting field by expanding laser beam, if the collecting filed is fixed. The second one is changing field angle base to accommodate laser divergence angle. The third one is setting a very narrow gating circuit to control acquisition circuit, which is shortly open only when fluorescence arriving. At some level, these methods all can reduce the background light. But after discussion, the third one is best with adding gating acquisition circuit to acquisition circuit instead of changing light path, which is effective and economic.

Exploring Noise: Sound Pollution.

ERIC Educational Resources Information Center

Rillo, Thomas J.

1979-01-01

Part one of a three-part series about noise pollution and its effects on humans. This section presents the background information for teachers who are preparing a unit on sound. The next issues will offer learning activities for measuring the effects of sound and some references. (SA)

Sensor system for heart sound biomonitor

NASA Astrophysics Data System (ADS)

Maple, Jarrad L.; Hall, Leonard T.; Agzarian, John; Abbott, Derek

1999-09-01

Heart sounds can be utilized more efficiently by medical doctors when they are displayed visually, rather than through a conventional stethoscope. A system whereby a digital stethoscope interfaces directly to a PC will be directly along with signal processing algorithms, adopted. The sensor is based on a noise cancellation microphone, with a 450 Hz bandwidth and is sampled at 2250 samples/sec with 12-bit resolution. Further to this, we discuss for comparison a piezo-based sensor with a 1 kHz bandwidth. A major problem is that the recording of the heart sound into these devices is subject to unwanted background noise which can override the heart sound and results in a poor visual representation. This noise originates from various sources such as skin contact with the stethoscope diaphragm, lung sounds, and other surrounding sounds such as speech. Furthermore we demonstrate a solution using 'wavelet denoising'. The wavelet transform is used because of the similarity between the shape of wavelets and the time-domain shape of a heartbeat sound. Thus coding of the waveform into the wavelet domain is achieved with relatively few wavelet coefficients, in contrast to the many Fourier components that would result from conventional decomposition. We show that the background noise can be dramatically reduced by a thresholding operation in the wavelet domain. The principle is that the background noise codes into many small broadband wavelet coefficients that can be removed without significant degradation of the signal of interest.

Metabolic and Respiratory Costs of Increasing Song Amplitude in Zebra Finches

PubMed Central

Zollinger, Sue Anne; Goller, Franz; Brumm, Henrik

2011-01-01

Bird song is a widely used model in the study of animal communication and sexual selection, and several song features have been shown to reflect the quality of the singer. Recent studies have demonstrated that song amplitude may be an honest signal of current condition in males and that females prefer high amplitude songs. In addition, birds raise the amplitude of their songs to communicate in noisy environments. Although it is generally assumed that louder song should be more costly to produce, there has been little empirical evidence to support this assumption. We tested the assumption by measuring oxygen consumption and respiratory patterns in adult male zebra finches (Taeniopygia guttata) singing at different amplitudes in different background noise conditions. As background noise levels increased, birds significantly increased the sound pressure level of their songs. We found that louder songs required significantly greater subsyringeal air sac pressure than quieter songs. Though increased pressure is probably achieved by increasing respiratory muscle activity, these increases did not correlate with measurable increases in oxygen consumption. In addition, we found that oxygen consumption increased in higher background noise, independent of singing behaviour. This observation supports previous research in mammals showing that high levels of environmental noise can induce physiological stress responses. While our study did not find that increasing vocal amplitude increased metabolic costs, further research is needed to determine whether there are other non-metabolic costs of singing louder or costs associated with chronic noise exposure. PMID:21915258

Searching for stochastic gravitational waves using data from the two colocated LIGO Hanford detectors

NASA Astrophysics Data System (ADS)

Aasi, J.; Abadie, J.; Abbott, B. P.; Abbott, R.; Abbott, T.; Abernathy, M. R.; Accadia, T.; Acernese, F.; Adams, C.; Adams, T.; Addesso, P.; Adhikari, R. X.; Affeldt, C.; Agathos, M.; Aggarwal, N.; Aguiar, O. D.; Ajith, P.; Allen, B.; Allocca, A.; Amador Ceron, E.; Amariutei, D.; Anderson, R. A.; Anderson, S. B.; Anderson, W. G.; Arai, K.; Araya, M. C.; Arceneaux, C.; Areeda, J.; Ast, S.; Aston, S. M.; Astone, P.; Aufmuth, P.; Aulbert, C.; Austin, L.; Aylott, B. E.; Babak, S.; Baker, P. T.; Ballardin, G.; Ballmer, S. W.; Barayoga, J. C.; Barker, D.; Barnum, S. H.; Barone, F.; Barr, B.; Barsotti, L.; Barsuglia, M.; Barton, M. A.; Bartos, I.; Bassiri, R.; Basti, A.; Batch, J.; Bauchrowitz, J.; Bauer, Th. S.; Bebronne, M.; Behnke, B.; Bejger, M.; Beker, M. G.; Bell, A. S.; Bell, C.; Belopolski, I.; Bergmann, G.; Berliner, J. M.; Bersanetti, D.; Bertolini, A.; Bessis, D.; Betzwieser, J.; Beyersdorf, P. T.; Bhadbhade, T.; Bilenko, I. A.; Billingsley, G.; Birch, J.; Biscans, S.; Bitossi, M.; Bizouard, M. A.; Black, E.; Blackburn, J. K.; Blackburn, L.; Blair, D.; Blom, M.; Bock, O.; Bodiya, T. P.; Boer, M.; Bogan, C.; Bond, C.; Bondu, F.; Bonelli, L.; Bonnand, R.; Bork, R.; Born, M.; Boschi, V.; Bose, S.; Bosi, L.; Bowers, J.; Bradaschia, C.; Brady, P. R.; Braginsky, V. B.; Branchesi, M.; Brannen, C. A.; Brau, J. E.; Breyer, J.; Briant, T.; Bridges, D. O.; Brillet, A.; Brinkmann, M.; Brisson, V.; Britzger, M.; Brooks, A. F.; Brown, D. A.; Brown, D. D.; Brückner, F.; Bulik, T.; Bulten, H. J.; Buonanno, A.; Buskulic, D.; Buy, C.; Byer, R. L.; Cadonati, L.; Cagnoli, G.; Calderón Bustillo, J.; Calloni, E.; Camp, J. B.; Campsie, P.; Cannon, K. C.; Canuel, B.; Cao, J.; Capano, C. D.; Carbognani, F.; Carbone, L.; Caride, S.; Castiglia, A.; Caudill, S.; Cavaglià, M.; Cavalier, F.; Cavalieri, R.; Cella, G.; Cepeda, C.; Cesarini, E.; Chakraborty, R.; Chalermsongsak, T.; Chao, S.; Charlton, P.; Chassande-Mottin, E.; Chen, X.; Chen, Y.; Chincarini, A.; Chiummo, A.; Cho, H. S.; Chow, J.; Christensen, N.; Chu, Q.; Chua, S. S. Y.; Chung, S.; Ciani, G.; Clara, F.; Clark, D. E.; Clark, J. A.; Cleva, F.; Coccia, E.; Cohadon, P.-F.; Colla, A.; Colombini, M.; Constancio, M.; Conte, A.; Cook, D.; Corbitt, T. R.; Cordier, M.; Cornish, N.; Corsi, A.; Costa, C. A.; Coughlin, M. W.; Coulon, J.-P.; Countryman, S.; Couvares, P.; Coward, D. M.; Cowart, M.; Coyne, D. C.; Craig, K.; Creighton, J. D. E.; Creighton, T. D.; Crowder, S. G.; Cumming, A.; Cunningham, L.; Cuoco, E.; Dahl, K.; Dal Canton, T.; Damjanic, M.; Danilishin, S. L.; D'Antonio, S.; Danzmann, K.; Dattilo, V.; Daudert, B.; Daveloza, H.; Davier, M.; Davies, G. S.; Daw, E. J.; Day, R.; Dayanga, T.; Debreczeni, G.; Degallaix, J.; Deleeuw, E.; Deléglise, S.; Del Pozzo, W.; Denker, T.; Dent, T.; Dereli, H.; Dergachev, V.; DeRosa, R. T.; De Rosa, R.; DeSalvo, R.; Dhurandhar, S.; Díaz, M.; Dietz, A.; Di Fiore, L.; Di Lieto, A.; Di Palma, I.; Di Virgilio, A.; Dmitry, K.; Donovan, F.; Dooley, K. L.; Doravari, S.; Drago, M.; Drever, R. W. P.; Driggers, J. C.; Du, Z.; Dumas, J.-C.; Dwyer, S.; Eberle, T.; Edwards, M.; Effler, A.; Ehrens, P.; Eichholz, J.; Eikenberry, S. S.; Endrőczi, G.; Essick, R.; Etzel, T.; Evans, K.; Evans, M.; Evans, T.; Factourovich, M.; Fafone, V.; Fairhurst, S.; Fang, Q.; Farr, B.; Farr, W.; Favata, M.; Fazi, D.; Fehrmann, H.; Feldbaum, D.; Ferrante, I.; Ferrini, F.; Fidecaro, F.; Finn, L. S.; Fiori, I.; Fisher, R.; Flaminio, R.; Foley, E.; Foley, S.; Forsi, E.; Fotopoulos, N.; Fournier, J.-D.; Franco, S.; Frasca, S.; Frasconi, F.; Frede, M.; Frei, M.; Frei, Z.; Freise, A.; Frey, R.; Fricke, T. T.; Fritschel, P.; Frolov, V. V.; Fujimoto, M.-K.; Fulda, P.; Fyffe, M.; Gair, J.; Gammaitoni, L.; Garcia, J.; Garufi, F.; Gehrels, N.; Gemme, G.; Genin, E.; Gennai, A.; Gergely, L.; Ghosh, S.; Giaime, J. A.; Giampanis, S.; Giardina, K. D.; Giazotto, A.; Gil-Casanova, S.; Gill, C.; Gleason, J.; Goetz, E.; Goetz, R.; Gondan, L.; González, G.; Gordon, N.; Gorodetsky, M. L.; Gossan, S.; Goßler, S.; Gouaty, R.; Graef, C.; Graff, P. B.; Granata, M.; Grant, A.; Gras, S.; Gray, C.; Greenhalgh, R. J. S.; Gretarsson, A. M.; Griffo, C.; Grote, H.; Grover, K.; Grunewald, S.; Guidi, G. M.; Guido, C.; Gushwa, K. E.; Gustafson, E. K.; Gustafson, R.; Hall, B.; Hall, E.; Hammer, D.; Hammond, G.; Hanke, M.; Hanks, J.; Hanna, C.; Hanson, J.; Harms, J.; Harry, G. M.; Harry, I. W.; Harstad, E. D.; Hartman, M. T.; Haughian, K.; Hayama, K.; Heefner, J.; Heidmann, A.; Heintze, M.; Heitmann, H.; Hello, P.; Hemming, G.; Hendry, M.; Heng, I. S.; Heptonstall, A. W.; Heurs, M.; Hild, S.; Hoak, D.; Hodge, K. A.; Holt, K.; Hong, T.; Hooper, S.; Horrom, T.; Hosken, D. J.; Hough, J.; Howell, E. J.; Hu, Y.; Hua, Z.; Huang, V.; Huerta, E. A.; Hughey, B.; Husa, S.; Huttner, S. H.; Huynh, M.; Huynh-Dinh, T.; Iafrate, J.; Ingram, D. R.; Inta, R.; Isogai, T.; Ivanov, A.; Iyer, B. R.; Izumi, K.; Jacobson, M.; James, E.; Jang, H.; Jang, Y. J.; Jaranowski, P.; Jiménez-Forteza, F.; Johnson, W. W.; Jones, D. I.; Jones, D.; Jones, R.; Jonker, R. J. G.; Ju, L.; Haris, K.; Kalmus, P.; Kalogera, V.; Kandhasamy, S.; Kang, G.; Kanner, J. B.; Kasprzack, M.; Kasturi, R.; Katsavounidis, E.; Katzman, W.; Kaufer, H.; Kaufman, K.; Kawabe, K.; Kawamura, S.; Kawazoe, F.; Kéfélian, F.; Keitel, D.; Kelley, D. B.; Kells, W.; Keppel, D. G.; Khalaidovski, A.; Khalili, F. Y.; Khazanov, E. A.; Kim, B. K.; Kim, C.; Kim, K.; Kim, N.; Kim, W.; Kim, Y.-M.; King, E.; King, P. J.; Kinzel, D. L.; Kissel, J. S.; Klimenko, S.; Kline, J.; Koehlenbeck, S.; Kokeyama, K.; Kondrashov, V.; Koranda, S.; Korth, W. Z.; Kowalska, I.; Kozak, D.; Kremin, A.; Kringel, V.; Krishnan, B.; Królak, A.; Kucharczyk, C.; Kudla, S.; Kuehn, G.; Kumar, A.; Kumar, D. Nanda; Kumar, P.; Kumar, R.; Kurdyumov, R.; Kwee, P.; Landry, M.; Lantz, B.; Larson, S.; Lasky, P. D.; Lawrie, C.; Lazzarini, A.; Leaci, P.; Lebigot, E. O.; Lee, C.-H.; Lee, H. K.; Lee, H. M.; Lee, J. J.; Lee, J.; Leonardi, M.; Leong, J. R.; Le Roux, A.; Leroy, N.; Letendre, N.; Levine, B.; Lewis, J. B.; Lhuillier, V.; Li, T. G. F.; Lin, A. C.; Littenberg, T. B.; Litvine, V.; Liu, F.; Liu, H.; Liu, Y.; Liu, Z.; Lloyd, D.; Lockerbie, N. A.; Lockett, V.; Lodhia, D.; Loew, K.; Logue, J.; Lombardi, A. L.; Lorenzini, M.; Loriette, V.; Lormand, M.; Losurdo, G.; Lough, J.; Luan, J.; Lubinski, M. J.; Lück, H.; Lundgren, A. P.; Macarthur, J.; Macdonald, E.; Machenschalk, B.; MacInnis, M.; Macleod, D. M.; Magana-Sandoval, F.; Mageswaran, M.; Mailand, K.; Majorana, E.; Maksimovic, I.; Malvezzi, V.; Man, N.; Manca, G. M.; Mandel, I.; Mandic, V.; Mangano, V.; Mantovani, M.; Marchesoni, F.; Marion, F.; Márka, S.; Márka, Z.; Markosyan, A.; Maros, E.; Marque, J.; Martelli, F.; Martellini, L.; Martin, I. W.; Martin, R. M.; Martini, G.; Martynov, D.; Marx, J. N.; Mason, K.; Masserot, A.; Massinger, T. J.; Matichard, F.; Matone, L.; Matzner, R. A.; Mavalvala, N.; May, G.; Mazumder, N.; Mazzolo, G.; McCarthy, R.; McClelland, D. E.; McGuire, S. C.; McIntyre, G.; McIver, J.; Meacher, D.; Meadors, G. D.; Mehmet, M.; Meidam, J.; Meier, T.; Melatos, A.; Mendell, G.; Mercer, R. A.; Meshkov, S.; Messenger, C.; Meyer, M. S.; Miao, H.; Michel, C.; Mikhailov, E.; Milano, L.; Miller, J.; Minenkov, Y.; Mingarelli, C. M. F.; Mitra, S.; Mitrofanov, V. P.; Mitselmakher, G.; Mittleman, R.; Moe, B.; Mohan, M.; Mohapatra, S. R. P.; Mokler, F.; Moraru, D.; Moreno, G.; Morgado, N.; Mori, T.; Morriss, S. R.; Mossavi, K.; Mours, B.; Mow-Lowry, C. M.; Mueller, C. L.; Mueller, G.; Mukherjee, S.; Mullavey, A.; Munch, J.; Murphy, D.; Murray, P. G.; Mytidis, A.; Nagy, M. F.; Nardecchia, I.; Nash, T.; Naticchioni, L.; Nayak, R.; Necula, V.; Neri, I.; Neri, M.; Newton, G.; Nguyen, T.; Nishida, E.; Nishizawa, A.; Nitz, A.; Nocera, F.; Nolting, D.; Normandin, M. E.; Nuttall, L. K.; Ochsner, E.; O'Dell, J.; Oelker, E.; Ogin, G. H.; Oh, J. J.; Oh, S. H.; Ohme, F.; Oppermann, P.; O'Reilly, B.; Ortega Larcher, W.; O'Shaughnessy, R.; Osthelder, C.; Ottaway, D. J.; Ottens, R. S.; Ou, J.; Overmier, H.; Owen, B. J.; Padilla, C.; Pai, A.; Palomba, C.; Pan, Y.; Pankow, C.; Paoletti, F.; Paoletti, R.; Paris, H.; Pasqualetti, A.; Passaquieti, R.; Passuello, D.; Pedraza, M.; Peiris, P.; Penn, S.; Perreca, A.; Phelps, M.; Pichot, M.; Pickenpack, M.; Piergiovanni, F.; Pierro, V.; Pinard, L.; Pindor, B.; Pinto, I. M.; Pitkin, M.; Poeld, J.; Poggiani, R.; Poole, V.; Postiglione, F.; Poux, C.; Predoi, V.; Prestegard, T.; Price, L. R.; Prijatelj, M.; Privitera, S.; Prodi, G. A.; Prokhorov, L.; Puncken, O.; Punturo, M.; Puppo, P.; Quetschke, V.; Quintero, E.; Quitzow-James, R.; Raab, F. J.; Rabeling, D. S.; Rácz, I.; Radkins, H.; Raffai, P.; Raja, S.; Rajalakshmi, G.; Rakhmanov, M.; Ramet, C.; Rapagnani, P.; Raymond, V.; Re, V.; Reed, C. M.; Reed, T.; Regimbau, T.; Reid, S.; Reitze, D. H.; Ricci, F.; Riesen, R.; Riles, K.; Robertson, N. A.; Robinet, F.; Rocchi, A.; Roddy, S.; Rodriguez, C.; Rodruck, M.; Roever, C.; Rolland, L.; Rollins, J. G.; Romano, J. D.; Romano, R.; Romanov, G.; Romie, J. H.; Rosińska, D.; Rowan, S.; Rüdiger, A.; Ruggi, P.; Ryan, K.; Salemi, F.; Sammut, L.; Sandberg, V.; Sanders, J.; Sannibale, V.; Santiago-Prieto, I.; Saracco, E.; Sassolas, B.; Sathyaprakash, B. S.; Saulson, P. R.; Savage, R.; Schilling, R.; Schnabel, R.; Schofield, R. M. S.; Schreiber, E.; Schuette, D.; Schulz, B.; Schutz, B. F.; Schwinberg, P.; Scott, J.; Scott, S. M.; Seifert, F.; Sellers, D.; Sengupta, A. S.; Sentenac, D.; Sequino, V.; Sergeev, A.; Shaddock, D.; Shah, S.; Shahriar, M. S.; Shaltev, M.; Shapiro, B.; Shawhan, P.; Shoemaker, D. H.; Sidery, T. L.; Siellez, K.; Siemens, X.; Sigg, D.; Simakov, D.; Singer, A.; Singer, L.; Sintes, A. M.; Skelton, G. R.; Slagmolen, B. J. J.; Slutsky, J.; Smith, J. R.; Smith, M. R.; Smith, R. J. E.; Smith-Lefebvre, N. D.; Soden, K.; Son, E. J.; Sorazu, B.; Souradeep, T.; Sperandio, L.; Staley, A.; Steinert, E.; Steinlechner, J.; Steinlechner, S.; Steplewski, S.; Stevens, D.; Stochino, A.; Stone, R.; Strain, K. A.; Straniero, N.; Strigin, S.; Stroeer, A. S.; Sturani, R.; Stuver, A. L.; Summerscales, T. Z.; Susmithan, S.; Sutton, P. J.; Swinkels, B.; Szeifert, G.; Tacca, M.; Talukder, D.; Tang, L.; Tanner, D. B.; Tarabrin, S. P.; Taylor, R.; ter Braack, A. P. M.; Thirugnanasambandam, M. P.; Thomas, M.; Thomas, P.; Thorne, K. A.; Thorne, K. S.; Thrane, E.; Tiwari, V.; Tokmakov, K. V.; Tomlinson, C.; Toncelli, A.; Tonelli, M.; Torre, O.; Torres, C. V.; Torrie, C. I.; Travasso, F.; Traylor, G.; Tse, M.; Ugolini, D.; Unnikrishnan, C. S.; Vahlbruch, H.; Vajente, G.; Vallisneri, M.; van den Brand, J. F. J.; Van Den Broeck, C.; van der Putten, S.; van der Sluys, M. V.; van Heijningen, J.; van Veggel, A. A.; Vass, S.; Vasúth, M.; Vaulin, R.; Vecchio, A.; Vedovato, G.; Veitch, P. J.; Veitch, J.; Venkateswara, K.; Verkindt, D.; Verma, S.; Vetrano, F.; Viceré, A.; Vincent-Finley, R.; Vinet, J.-Y.; Vitale, S.; Vitale, S.; Vlcek, B.; Vo, T.; Vocca, H.; Vorvick, C.; Vousden, W. D.; Vrinceanu, D.; Vyachanin, S. P.; Wade, A.; Wade, L.; Wade, M.; Waldman, S. J.; Walker, M.; Wallace, L.; Wan, Y.; Wang, J.; Wang, M.; Wang, X.; Wanner, A.; Ward, R. L.; Was, M.; Weaver, B.; Wei, L.-W.; Weinert, M.; Weinstein, A. J.; Weiss, R.; Welborn, T.; Wen, L.; Wessels, P.; West, M.; Westphal, T.; Wette, K.; Whelan, J. T.; White, D. J.; Whiting, B. F.; Wibowo, S.; Wiesner, K.; Wilkinson, C.; Williams, L.; Williams, R.; Williams, T.; Willis, J. L.; Willke, B.; Wimmer, M.; Winkelmann, L.; Winkler, W.; Wipf, C. C.; Wittel, H.; Woan, G.; Worden, J.; Yablon, J.; Yakushin, I.; Yamamoto, H.; Yancey, C. C.; Yang, H.; Yeaton-Massey, D.; Yoshida, S.; Yum, H.; Yvert, M.; ZadroŻny, A.; Zanolin, M.; Zendri, J.-P.; Zhang, F.; Zhang, L.; Zhao, C.; Zhu, H.; Zhu, X. J.; Zotov, N.; Zucker, M. E.; Zweizig, J.; LIGO Scientific Collaboration; Virgo Collaboration

2015-01-01

Searches for a stochastic gravitational-wave background (SGWB) using terrestrial detectors typically involve cross-correlating data from pairs of detectors. The sensitivity of such cross-correlation analyses depends, among other things, on the separation between the two detectors: the smaller the separation, the better the sensitivity. Hence, a colocated detector pair is more sensitive to a gravitational-wave background than a noncolocated detector pair. However, colocated detectors are also expected to suffer from correlated noise from instrumental and environmental effects that could contaminate the measurement of the background. Hence, methods to identify and mitigate the effects of correlated noise are necessary to achieve the potential increase in sensitivity of colocated detectors. Here we report on the first SGWB analysis using the two LIGO Hanford detectors and address the complications arising from correlated environmental noise. We apply correlated noise identification and mitigation techniques to data taken by the two LIGO Hanford detectors, H1 and H2, during LIGO's fifth science run. At low frequencies, 40-460 Hz, we are unable to sufficiently mitigate the correlated noise to a level where we may confidently measure or bound the stochastic gravitational-wave signal. However, at high frequencies, 460-1000 Hz, these techniques are sufficient to set a 95% confidence level upper limit on the gravitational-wave energy density of Ω (f )<7.7 ×1 0-4(f /900 Hz )3 , which improves on the previous upper limit by a factor of ˜180 . In doing so, we demonstrate techniques that will be useful for future searches using advanced detectors, where correlated noise (e.g., from global magnetic fields) may affect even widely separated detectors.

Searching for Stochastic Gravitational Waves Using Data from the Two Co-Located LIGO Hanford Detectors

NASA Technical Reports Server (NTRS)

Aasi, J.; Abadie, J.; Abbott, B. P.; Abbott, R.; Abbott, T.; Abernathy, M. R.; Accadia, T.; Acernese, F.; Adams, C.; Adams, T.;

Estimation of background noise level on seismic station using statistical analysis for improved analysis accuracy

NASA Astrophysics Data System (ADS)

Han, S. M.; Hahm, I.

2015-12-01

We evaluated the background noise level of seismic stations in order to collect the observation data of high quality and produce accurate seismic information. Determining of the background noise level was used PSD (Power Spectral Density) method by McNamara and Buland (2004) in this study. This method that used long-term data is influenced by not only innate electronic noise of sensor and a pulse wave resulting from stabilizing but also missing data and controlled by the specified frequency which is affected by the irregular signals without site characteristics. It is hard and inefficient to implement process that filters out the abnormal signal within the automated system. To solve these problems, we devised a method for extracting the data which normally distributed with 90 to 99% confidence intervals at each period. The availability of the method was verified using 62-seismic stations with broadband and short-period sensors operated by the KMA (Korea Meteorological Administration). Evaluation standards were NHNM (New High Noise Model) and NLNM (New Low Noise Model) published by the USGS (United States Geological Survey). It was designed based on the western United States. However, Korean Peninsula surrounded by the ocean on three sides has a complicated geological structure and a high population density. So, we re-designed an appropriate model in Korean peninsula by statistically combined result. The important feature is that secondary-microseism peak appeared at a higher frequency band. Acknowledgements: This research was carried out as a part of "Research for the Meteorological and Earthquake Observation Technology and Its Application" supported by the 2015 National Institute of Meteorological Research (NIMR) in the Korea Meteorological Administration.

On the relationship between auditory cognition and speech intelligibility in cochlear implant users: An ERP study.

PubMed

Finke, Mareike; Büchner, Andreas; Ruigendijk, Esther; Meyer, Martin; Sandmann, Pascale

2016-07-01

There is a high degree of variability in speech intelligibility outcomes across cochlear-implant (CI) users. To better understand how auditory cognition affects speech intelligibility with the CI, we performed an electroencephalography study in which we examined the relationship between central auditory processing, cognitive abilities, and speech intelligibility. Postlingually deafened CI users (N=13) and matched normal-hearing (NH) listeners (N=13) performed an oddball task with words presented in different background conditions (quiet, stationary noise, modulated noise). Participants had to categorize words as living (targets) or non-living entities (standards). We also assessed participants' working memory (WM) capacity and verbal abilities. For the oddball task, we found lower hit rates and prolonged response times in CI users when compared with NH listeners. Noise-related prolongation of the N1 amplitude was found for all participants. Further, we observed group-specific modulation effects of event-related potentials (ERPs) as a function of background noise. While NH listeners showed stronger noise-related modulation of the N1 latency, CI users revealed enhanced modulation effects of the N2/N4 latency. In general, higher-order processing (N2/N4, P3) was prolonged in CI users in all background conditions when compared with NH listeners. Longer N2/N4 latency in CI users suggests that these individuals have difficulties to map acoustic-phonetic features to lexical representations. These difficulties seem to be increased for speech-in-noise conditions when compared with speech in quiet background. Correlation analyses showed that shorter ERP latencies were related to enhanced speech intelligibility (N1, N2/N4), better lexical fluency (N1), and lower ratings of listening effort (N2/N4) in CI users. In sum, our findings suggest that CI users and NH listeners differ with regards to both the sensory and the higher-order processing of speech in quiet as well as in noisy background conditions. Our results also revealed that verbal abilities are related to speech processing and speech intelligibility in CI users, confirming the view that auditory cognition plays an important role for CI outcome. We conclude that differences in auditory-cognitive processing contribute to the variability in speech performance outcomes observed in CI users. Copyright © 2016 Elsevier Ltd. All rights reserved.

Ballistic Missile Defense Glossary Version 3.0.

DTIC Science & Technology

1997-06-01

The suppression of background noise for the improvement of an object signal. Battlefield Area Evaluation (USA term). Best and Final Offer...field of the lens are focused. An FPA is a matrix of photon sensitive detectors which, when combined with low noise preamplifiers, provides image data...orbital planes with an orbit period of 12 hours at 10,900 nautical miles altitude. Each satellite transmits three L-band, pseudo-random noise -coded

Optical communication noise rejection using corelated photons

NASA Technical Reports Server (NTRS)

Jackson, D.; Hockney, G. M.; Dowling, J. P.

2002-01-01

This paper describes a completely new way to perform noise rejection using photons correlated through quantum entanglement to improve an optical communications link in the presence of uncorrelated noise. In particular, a detailed analysis is made of the case where a classical link would be saturated by an intense background, such as when a satellite is in front of the sun, and identifies where the quantum correlating system has superior performance.

Measurement of Model Noise in a Hard-Wall Wind Tunnel

NASA Technical Reports Server (NTRS)

Soderman, Paul T.

2006-01-01

Identification, analysis, and control of fluid-mechanically-generated sound from models of aircraft and automobiles in special low-noise, semi-anechoic wind tunnels are an important research endeavor. Such studies can also be done in aerodynamic wind tunnels that have hard walls if phased microphone arrays are used to focus on the noise-source regions and reject unwanted reflections or background noise. Although it may be difficult to simulate the total flyover or drive-by noise in a closed wind tunnel, individual noise sources can be isolated and analyzed. An acoustic and aerodynamic study was made of a 7-percent-scale aircraft model in a NASA Ames 7-by-10-ft (about 2-by-3-m) wind tunnel for the purpose of identifying and attenuating airframe noise sources. Simulated landing, takeoff, and approach configurations were evaluated at Mach 0.26. Using a phased microphone array mounted in the ceiling over the inverted model, various noise sources in the high-lift system, landing gear, fins, and miscellaneous other components were located and compared for sound level and frequency at one flyover location. Numerous noise-alleviation devices and modifications of the model were evaluated. Simultaneously with acoustic measurements, aerodynamic forces were recorded to document aircraft conditions and any performance changes caused by geometric modifications. Most modern microphone-array systems function in the frequency domain in the sense that spectra of the microphone outputs are computed, then operations are performed on the matrices of microphone-signal cross-spectra. The entire acoustic field at one station in such a system is acquired quickly and interrogated during postprocessing. Beam-forming algorithms are employed to scan a plane near the model surface and locate noise sources while rejecting most background noise and spurious reflections. In the case of the system used in this study, previous studies in the wind tunnel have identified noise sources up to 19 dB below the normal background noise of the wind tunnel. Theoretical predictions of array performance are used to minimize the width and the side lobes of the beam pattern of the microphone array for a given test arrangement. To capture flyover noise of the inverted model, a 104-element microphone array in a 622-mm-diameter cluster was installed in a 19-mm-thick poly(methyl methacrylate) plate in the ceiling of the test section of the wind tunnel above the aircraft model (see Figure 1). The microphones were of the condenser type, and their diaphragms were mounted flush in the array plate, which was recessed 12.7 mm into the ceiling and covered by a porous aromatic polyamide cloth (not shown in the figure) to minimize boundary-layer noise. This design caused the level of flow noise to be much less than that of flush-mount designs. The drawback of this design was that the cloth attenuated sound somewhat and created acoustic resonances that could grow to several dB at a frequency of 10 kHz.

The Shock Pulse Index and Its Application in the Fault Diagnosis of Rolling Element Bearings

PubMed Central

Sun, Peng; Liao, Yuhe; Lin, Jin

2017-01-01

The properties of the time domain parameters of vibration signals have been extensively studied for the fault diagnosis of rolling element bearings (REBs). Parameters like kurtosis and Envelope Harmonic-to-Noise Ratio are the most widely applied in this field and some important progress has been made. However, since only one-sided information is contained in these parameters, problems still exist in practice when the signals collected are of complicated structure and/or contaminated by strong background noises. A new parameter, named Shock Pulse Index (SPI), is proposed in this paper. It integrates the mutual advantages of both the parameters mentioned above and can help effectively identify fault-related impulse components under conditions of interference of strong background noises, unrelated harmonic components and random impulses. The SPI optimizes the parameters of Maximum Correlated Kurtosis Deconvolution (MCKD), which is used to filter the signals under consideration. Finally, the transient information of interest contained in the filtered signal can be highlighted through demodulation with the Teager Energy Operator (TEO). Fault-related impulse components can therefore be extracted accurately. Simulations show the SPI can correctly indicate the fault impulses under the influence of strong background noises, other harmonic components and aperiodic impulse and experiment analyses verify the effectiveness and correctness of the proposed method. PMID:28282883

SiPM electro-optical detection system noise suppression method

NASA Astrophysics Data System (ADS)

Bi, Xiangli; Yang, Suhui; Hu, Tao; Song, Yiheng

2014-11-01

In this paper, the single photon detection principle of Silicon Photomultipliers (SiPM) device is introduced. The main noise factors that infect the sensitivity of the electro-optical detection system are analyzed, including background light noise, detector dark noise, preamplifier noise and signal light noise etc. The Optical, electrical and thermodynamic methods are used to suppress the SiPM electro-optical detection system noise, which improved the response sensitivity of the detector. Using SiPM optoelectronic detector with a even high sensitivity, together with small field large aperture optical system, high cutoff narrow bandwidth filters, low-noise operational amplifier circuit, the modular design of functional circuit, semiconductor refrigeration technology, greatly improved the sensitivity of optical detection system, reduced system noise and achieved long-range detection of weak laser radiation signal. Theoretical analysis and experimental results show that the proposed methods are reasonable and efficient.

Advanced Background Subtraction Applied to Aeroacoustic Wind Tunnel Testing

NASA Technical Reports Server (NTRS)

Bahr, Christopher J.; Horne, William C.

2015-01-01

An advanced form of background subtraction is presented and applied to aeroacoustic wind tunnel data. A variant of this method has seen use in other fields such as climatology and medical imaging. The technique, based on an eigenvalue decomposition of the background noise cross-spectral matrix, is robust against situations where isolated background auto-spectral levels are measured to be higher than levels of combined source and background signals. It also provides an alternate estimate of the cross-spectrum, which previously might have poor definition for low signal-to-noise ratio measurements. Simulated results indicate similar performance to conventional background subtraction when the subtracted spectra are weaker than the true contaminating background levels. Superior performance is observed when the subtracted spectra are stronger than the true contaminating background levels. Experimental results show limited success in recovering signal behavior for data where conventional background subtraction fails. They also demonstrate the new subtraction technique's ability to maintain a proper coherence relationship in the modified cross-spectral matrix. Beam-forming and de-convolution results indicate the method can successfully separate sources. Results also show a reduced need for the use of diagonal removal in phased array processing, at least for the limited data sets considered.

Invited article: Characterization of background sources in space-based time-of-flight mass spectrometers.

PubMed

Gilbert, J A; Gershman, D J; Gloeckler, G; Lundgren, R A; Zurbuchen, T H; Orlando, T M; McLain, J; von Steiger, R

2014-09-01

For instruments that use time-of-flight techniques to measure space plasma, there are common sources of background signals that evidence themselves in the data. The background from these sources may increase the complexity of data analysis and reduce the signal-to-noise response of the instrument, thereby diminishing the science value or usefulness of the data. This paper reviews several sources of background commonly found in time-of-flight mass spectrometers and illustrates their effect in actual data using examples from ACE-SWICS and MESSENGER-FIPS. Sources include penetrating particles and radiation, UV photons, energy straggling and angular scattering, electron stimulated desorption of ions, ion-induced electron emission, accidental coincidence events, and noise signatures from instrument electronics. Data signatures of these sources are shown, as well as mitigation strategies and design considerations for future instruments.

Research on the algorithm of infrared target detection based on the frame difference and background subtraction method

NASA Astrophysics Data System (ADS)

Liu, Yun; Zhao, Yuejin; Liu, Ming; Dong, Liquan; Hui, Mei; Liu, Xiaohua; Wu, Yijian

2015-09-01

As an important branch of infrared imaging technology, infrared target tracking and detection has a very important scientific value and a wide range of applications in both military and civilian areas. For the infrared image which is characterized by low SNR and serious disturbance of background noise, an innovative and effective target detection algorithm is proposed in this paper, according to the correlation of moving target frame-to-frame and the irrelevance of noise in sequential images based on OpenCV. Firstly, since the temporal differencing and background subtraction are very complementary, we use a combined detection method of frame difference and background subtraction which is based on adaptive background updating. Results indicate that it is simple and can extract the foreground moving target from the video sequence stably. For the background updating mechanism continuously updating each pixel, we can detect the infrared moving target more accurately. It paves the way for eventually realizing real-time infrared target detection and tracking, when transplanting the algorithms on OpenCV to the DSP platform. Afterwards, we use the optimal thresholding arithmetic to segment image. It transforms the gray images to black-white images in order to provide a better condition for the image sequences detection. Finally, according to the relevance of moving objects between different frames and mathematical morphology processing, we can eliminate noise, decrease the area, and smooth region boundaries. Experimental results proves that our algorithm precisely achieve the purpose of rapid detection of small infrared target.

Stability of monitoring weak changes in multiply scattering media with ambient noise correlation: laboratory experiments.

PubMed

Hadziioannou, Céline; Larose, Eric; Coutant, Olivier; Roux, Philippe; Campillo, Michel

2009-06-01

Previous studies have shown that small changes can be monitored in a scattering medium by observing phase shifts in the coda. Passive monitoring of weak changes through ambient noise correlation has already been applied to seismology, acoustics, and engineering. Usually, this is done under the assumption that a properly reconstructed Green function (GF), as well as stable background noise sources, is necessary. In order to further develop this monitoring technique, a laboratory experiment was performed in the 2.5 MHz range in a gel with scattering inclusions, comparing an active (pulse-echo) form of monitoring to a passive (correlation) one. Present results show that temperature changes in the medium can be observed even if the GF of the medium is not reconstructed. Moreover, this article establishes that the GF reconstruction in the correlations is not a necessary condition: The only condition to monitoring with correlation (passive experiment) is the relative stability of the background noise structure.

Stochastic resonant damping in a noisy monostable system: theory and experiment.

PubMed

Volpe, Giovanni; Perrone, Sandro; Rubi, J Miguel; Petrov, Dmitri

2008-05-01

Usually in the presence of a background noise an increased effort put in controlling a system stabilizes its behavior. Rarely it is thought that an increased control of the system can lead to a looser response and, therefore, to a poorer performance. Strikingly there are many systems that show this weird behavior; examples can be drawn form physical, biological, and social systems. Until now no simple and general mechanism underlying such behaviors has been identified. Here we show that such a mechanism, named stochastic resonant damping, can be provided by the interplay between the background noise and the control exerted on the system. We experimentally verify our prediction on a physical model system based on a colloidal particle held in an oscillating optical potential. Our result adds a tool for the study of intrinsically noisy phenomena, joining the many constructive facets of noise identified in the past decades-for example, stochastic resonance, noise-induced activation, and Brownian ratchets.

SNSMIL, a real-time single molecule identification and localization algorithm for super-resolution fluorescence microscopy

PubMed Central

Tang, Yunqing; Dai, Luru; Zhang, Xiaoming; Li, Junbai; Hendriks, Johnny; Fan, Xiaoming; Gruteser, Nadine; Meisenberg, Annika; Baumann, Arnd; Katranidis, Alexandros; Gensch, Thomas

2015-01-01

Single molecule localization based super-resolution fluorescence microscopy offers significantly higher spatial resolution than predicted by Abbe’s resolution limit for far field optical microscopy. Such super-resolution images are reconstructed from wide-field or total internal reflection single molecule fluorescence recordings. Discrimination between emission of single fluorescent molecules and background noise fluctuations remains a great challenge in current data analysis. Here we present a real-time, and robust single molecule identification and localization algorithm, SNSMIL (Shot Noise based Single Molecule Identification and Localization). This algorithm is based on the intrinsic nature of noise, i.e., its Poisson or shot noise characteristics and a new identification criterion, QSNSMIL, is defined. SNSMIL improves the identification accuracy of single fluorescent molecules in experimental or simulated datasets with high and inhomogeneous background. The implementation of SNSMIL relies on a graphics processing unit (GPU), making real-time analysis feasible as shown for real experimental and simulated datasets. PMID:26098742

Image processing of metal surface with structured light

NASA Astrophysics Data System (ADS)

Luo, Cong; Feng, Chang; Wang, Congzheng

2014-09-01

In structured light vision measurement system, the ideal image of structured light strip, in addition to black background , contains only the gray information of the position of the stripe. However, the actual image contains image noise, complex background and so on, which does not belong to the stripe, and it will cause interference to useful information. To extract the stripe center of mental surface accurately, a new processing method was presented. Through adaptive median filtering, the noise can be preliminary removed, and the noise which introduced by CCD camera and measured environment can be further removed with difference image method. To highlight fine details and enhance the blurred regions between the stripe and noise, the sharping algorithm is used which combine the best features of Laplacian operator and Sobel operator. Morphological opening operation and closing operation are used to compensate the loss of information.Experimental results show that this method is effective in the image processing, not only to restrain the information but also heighten contrast. It is beneficial for the following processing.

The Potential Role of the cABR in Assessment and Management of Hearing Impairment

PubMed Central

Anderson, Samira; Kraus, Nina

2013-01-01

Hearing aid technology has improved dramatically in the last decade, especially in the ability to adaptively respond to dynamic aspects of background noise. Despite these advancements, however, hearing aid users continue to report difficulty hearing in background noise and having trouble adjusting to amplified sound quality. These difficulties may arise in part from current approaches to hearing aid fittings, which largely focus on increased audibility and management of environmental noise. These approaches do not take into account the fact that sound is processed all along the auditory system from the cochlea to the auditory cortex. Older adults represent the largest group of hearing aid wearers; yet older adults are known to have deficits in temporal resolution in the central auditory system. Here we review evidence that supports the use of the auditory brainstem response to complex sounds (cABR) in the assessment of hearing-in-noise difficulties and auditory training efficacy in older adults. PMID:23431313

Sensitivity of an imaging space infrared interferometer.

PubMed

Nakajima, T; Matsuhara, H

2001-02-01

We study the sensitivities of space infrared interferometers. We formulate the signal-to-noise ratios of infrared images obtained by aperture synthesis in the presence of source shot noise, background shot noise, and detector read noise. We consider the case in which n beams are combined pairwise at n(n-1)/2 detectors and the case in which all the n beams are combined at a single detector. We apply the results to future missions, Terrestrial Planet Finder and Darwin. We also discuss the potential of a far-infrared interferometer for a deep galaxy survey.

Some propulsion system noise data handling conventions and computer programs used at the Lewis Research Center

NASA Technical Reports Server (NTRS)

Montegani, F. J.

1974-01-01

Methods of handling one-third-octave band noise data originating from the outdoor full-scale fan noise facility and the engine acoustic facility at the Lewis Research Center are presented. Procedures for standardizing, retrieving, extrapolating, and reporting these data are explained. Computer programs are given which are used to accomplish these and other noise data analysis tasks. This information is useful as background for interpretation of data from these facilities appearing in NASA reports and can aid data exchange by promoting standardization.

A Comparison of seismic instrument noise coherence analysis techniques

USGS Publications Warehouse

Ringler, A.T.; Hutt, C.R.; Evans, J.R.; Sandoval, L.D.

2011-01-01

The self-noise of a seismic instrument is a fundamental characteristic used to evaluate the quality of the instrument. It is important to be able to measure this self-noise robustly, to understand how differences among test configurations affect the tests, and to understand how different processing techniques and isolation methods (from nonseismic sources) can contribute to differences in results. We compare two popular coherence methods used for calculating incoherent noise, which is widely used as an estimate of instrument self-noise (incoherent noise and self-noise are not strictly identical but in observatory practice are approximately equivalent; Holcomb, 1989; Sleeman et al., 2006). Beyond directly comparing these two coherence methods on similar models of seismometers, we compare how small changes in test conditions can contribute to incoherent-noise estimates. These conditions include timing errors, signal-to-noise ratio changes (ratios between background noise and instrument incoherent noise), relative sensor locations, misalignment errors, processing techniques, and different configurations of sensor types.

Quantum correlation measurements in interferometric gravitational-wave detectors

NASA Astrophysics Data System (ADS)

Martynov, D. V.; Frolov, V. V.; Kandhasamy, S.; Izumi, K.; Miao, H.; Mavalvala, N.; Hall, E. D.; Lanza, R.; Abbott, B. P.; Abbott, R.; Abbott, T. D.; Adams, C.; Adhikari, R. X.; Anderson, S. B.; Ananyeva, A.; Appert, S.; Arai, K.; Aston, S. M.; Ballmer, S. W.; Barker, D.; Barr, B.; Barsotti, L.; Bartlett, J.; Bartos, I.; Batch, J. C.; Bell, A. S.; Betzwieser, J.; Billingsley, G.; Birch, J.; Biscans, S.; Biwer, C.; Blair, C. D.; Bork, R.; Brooks, A. F.; Ciani, G.; Clara, F.; Countryman, S. T.; Cowart, M. J.; Coyne, D. C.; Cumming, A.; Cunningham, L.; Danzmann, K.; Da Silva Costa, C. F.; Daw, E. J.; DeBra, D.; DeRosa, R. T.; DeSalvo, R.; Dooley, K. L.; Doravari, S.; Driggers, J. C.; Dwyer, S. E.; Effler, A.; Etzel, T.; Evans, M.; Evans, T. M.; Factourovich, M.; Fair, H.; Fernández Galiana, A.; Fisher, R. P.; Fritschel, P.; Fulda, P.; Fyffe, M.; Giaime, J. A.; Giardina, K. D.; Goetz, E.; Goetz, R.; Gras, S.; Gray, C.; Grote, H.; Gushwa, K. E.; Gustafson, E. K.; Gustafson, R.; Hammond, G.; Hanks, J.; Hanson, J.; Hardwick, T.; Harry, G. M.; Heintze, M. C.; Heptonstall, A. W.; Hough, J.; Jones, R.; Karki, S.; Kasprzack, M.; Kaufer, S.; Kawabe, K.; Kijbunchoo, N.; King, E. J.; King, P. J.; Kissel, J. S.; Korth, W. Z.; Kuehn, G.; Landry, M.; Lantz, B.; Lockerbie, N. A.; Lormand, M.; Lundgren, A. P.; MacInnis, M.; Macleod, D. M.; Márka, S.; Márka, Z.; Markosyan, A. S.; Maros, E.; Martin, I. W.; Mason, K.; Massinger, T. J.; Matichard, F.; McCarthy, R.; McClelland, D. E.; McCormick, S.; McIntyre, G.; McIver, J.; Mendell, G.; Merilh, E. L.; Meyers, P. M.; Miller, J.; Mittleman, R.; Moreno, G.; Mueller, G.; Mullavey, A.; Munch, J.; Nuttall, L. K.; Oberling, J.; Oppermann, P.; Oram, Richard J.; O'Reilly, B.; Ottaway, D. J.; Overmier, H.; Palamos, J. R.; Paris, H. R.; Parker, W.; Pele, A.; Penn, S.; Phelps, M.; Pierro, V.; Pinto, I.; Principe, M.; Prokhorov, L. G.; Puncken, O.; Quetschke, V.; Quintero, E. A.; Raab, F. J.; Radkins, H.; Raffai, P.; Reid, S.; Reitze, D. H.; Robertson, N. A.; Rollins, J. G.; Roma, V. J.; Romie, J. H.; Rowan, S.; Ryan, K.; Sadecki, T.; Sanchez, E. J.; Sandberg, V.; Savage, R. L.; Schofield, R. M. S.; Sellers, D.; Shaddock, D. A.; Shaffer, T. J.; Shapiro, B.; Shawhan, P.; Shoemaker, D. H.; Sigg, D.; Slagmolen, B. J. J.; Smith, B.; Smith, J. R.; Sorazu, B.; Staley, A.; Strain, K. A.; Tanner, D. B.; Taylor, R.; Thomas, M.; Thomas, P.; Thorne, K. A.; Thrane, E.; Torrie, C. I.; Traylor, G.; Vajente, G.; Valdes, G.; van Veggel, A. A.; Vecchio, A.; Veitch, P. J.; Venkateswara, K.; Vo, T.; Vorvick, C.; Walker, M.; Ward, R. L.; Warner, J.; Weaver, B.; Weiss, R.; Weßels, P.; Willke, B.; Wipf, C. C.; Worden, J.; Wu, G.; Yamamoto, H.; Yancey, C. C.; Yu, Hang; Yu, Haocun; Zhang, L.; Zucker, M. E.; Zweizig, J.; LSC Instrument Authors

2017-04-01

Quantum fluctuations in the phase and amplitude quadratures of light set limitations on the sensitivity of modern optical instruments. The sensitivity of the interferometric gravitational-wave detectors, such as the Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO), is limited by quantum shot noise, quantum radiation pressure noise, and a set of classical noises. We show how the quantum properties of light can be used to distinguish these noises using correlation techniques. Particularly, in the first part of the paper we show estimations of the coating thermal noise and gas phase noise, hidden below the quantum shot noise in the Advanced LIGO sensitivity curve. We also make projections on the observatory sensitivity during the next science runs. In the second part of the paper we discuss the correlation technique that reveals the quantum radiation pressure noise from the background of classical noises and shot noise. We apply this technique to the Advanced LIGO data, collected during the first science run, and experimentally estimate the quantum correlations and quantum radiation pressure noise in the interferometer.

Joint Service Aircrew Mask (JSAM) - Tactical Aircraft (TA) A/P22P-14A Respirator Assembly (V)5: Speech Intelligibility Performance with Double Hearing Protection, HGU-84/P Flight Helmet

DTIC Science & Technology

2017-04-06

Pressure Level (SPL) background pink noise. The speech intelligibility tests shall result in a Modified Rhyme Test (MRT) score as listed below...Speech intelligibility testing shall be measured per ANSI S3.2 for each background pink noise level using a minimum of ten talkers and of ten...listeners. The test shall be conducted wearing the JSAM-TA using appropriate communication 6 DISTRIBUTION STATEMENT A: Approved for public release

Summary Report of the Defense Sciences Research Council Summer Conference Held in La Jolla, California on July 6 - 31, 1992.

DTIC Science & Technology

1992-07-01

environments of high temperature or high electrical background noise . The sensitivity or speed of the sensor may not be adequate. The sensor signal may be...hard to interpret, or to deconvolve from background noise . These are all issues that must be addressed; however, at the present, there is still much...WAVELENGTH 3 (4 AND 8-101gM) QWIP DETECTOR I I i QW #2 WAFER MOW #1 Substrate THREE TERMINAL DEVICE I UNEAR RRA /Output Device #2Output Device #1 Sp

Full characterisation of a background limited antenna coupled KID over an octave of bandwidth for THz radiation

NASA Astrophysics Data System (ADS)

Bueno, J.; Yurduseven, O.; Yates, S. J. C.; Llombart, N.; Murugesan, V.; Thoen, D. J.; Baryshev, A. M.; Neto, A.; Baselmans, J. J. A.

2017-06-01

We present the design, fabrication, and full characterisation (sensitivity, beam pattern, and frequency response) of a background limited broadband antenna coupled kinetic inductance detector covering the frequency range from 1.4 to 2.8 THz. This device shows photon noise limited performance with a noise equivalent power of 2.5 × 10-19 W/Hz1/2 at 1.55 THz and can be easily scaled to a kilo-pixel array. The measured optical efficiency, beam pattern, and antenna frequency response match very well the simulations.

Influence of range-gated intensifiers on underwater imaging system SNR

NASA Astrophysics Data System (ADS)

Wang, Xia; Hu, Ling; Zhi, Qiang; Chen, Zhen-yue; Jin, Wei-qi

2013-08-01

Range-gated technology has been a hot research field in recent years due to its high effective back scattering eliminating. As a result, it can enhance the contrast between a target and its background and extent the working distance of the imaging system. The underwater imaging system is required to have the ability to image in low light level conditions, as well as the ability to eliminate the back scattering effect, which means that the receiver has to be high-speed external trigger function, high resolution, high sensitivity, low noise, higher gain dynamic range. When it comes to an intensifier, the noise characteristics directly restrict the observation effect and range of the imaging system. The background noise may decrease the image contrast and sharpness, even covering the signal making it impossible to recognize the target. So it is quite important to investigate the noise characteristics of intensifiers. SNR is an important parameter reflecting the noise features of a system. Through the use of underwater laser range-gated imaging prediction model, and according to the linear SNR system theory, the gated imaging noise performance of the present market adopted super second generation and generation Ⅲ intensifiers were theoretically analyzed. Based on the active laser underwater range-gated imaging model, the effect to the system by gated intensifiers and the relationship between the system SNR and MTF were studied. Through theoretical and simulation analysis to the image intensifier background noise and SNR, the different influence on system SNR by super second generation and generation Ⅲ ICCD was obtained. Range-gated system SNR formula was put forward, and compared the different effect influence on the system by using two kind of ICCDs was compared. According to the matlab simulation, a detailed analysis was carried out theoretically. All the work in this paper lays a theoretical foundation to further eliminating back scattering effect, improving image SNR, designing and manufacturing higher performance underwater range-gated imaging systems.

ANOPP2 User's Manual: Version 1.2

NASA Technical Reports Server (NTRS)

Lopes, L. V.; Burley, C. L.

2016-01-01

This manual documents the Aircraft NOise Prediction Program 2 (ANOPP2). ANOPP2 is a toolkit that includes a framework, noise prediction methods, and peripheral software to aid a user in predicting and understanding aircraft noise. This manual includes an explanation of the overall design and structure of ANOPP2, including a brief introduction to aircraft noise prediction and the ANOPP2 background, philosophy, and architecture. The concept of nested acoustic data surfaces and its application to a mixed-fidelity noise prediction are presented. The structure and usage of ANOPP2, which includes the communication between the user, the ANOPP2 framework, and noise prediction methods, are presented for two scenarios: wind-tunnel and flight. These scenarios serve to provide the user with guidance and documentation references for performing a noise prediction using ANOPP2.

Method of recognizing the high-speed railway noise barriers based on the distance image

NASA Astrophysics Data System (ADS)

Ma, Le; Shao, Shuangyun; Feng, Qibo; Liu, Bingqian; Kim, Chol Ryong

2016-10-01

The damage or lack of the noise barriers is one of the important hidden troubles endangering the safety of high-speed railway. In order to obtain the vibration information of the noise barriers, the online detection systems based on laser vision were proposed. The systems capture images of the laser stripe on the noise barriers and export data files containing distance information between the detection systems on the train and the noise barriers. The vibration status or damage of the noise barriers can be estimated depending on the distance information. In this paper, we focused on the method of separating the area of noise barrier from the background automatically. The test results showed that the proposed method is in good efficiency and accuracy.

Techniques to improve the accuracy of noise power spectrum measurements in digital x-ray imaging based on background trends removal.

PubMed

Zhou, Zhongxing; Gao, Feng; Zhao, Huijuan; Zhang, Lixin

2011-03-01

Noise characterization through estimation of the noise power spectrum (NPS) is a central component of the evaluation of digital x-ray systems. Extensive works have been conducted to achieve accurate and precise measurement of NPS. One approach to improve the accuracy of the NPS measurement is to reduce the statistical variance of the NPS results by involving more data samples. However, this method is based on the assumption that the noise in a radiographic image is arising from stochastic processes. In the practical data, the artifactuals always superimpose on the stochastic noise as low-frequency background trends and prevent us from achieving accurate NPS. The purpose of this study was to investigate an appropriate background detrending technique to improve the accuracy of NPS estimation for digital x-ray systems. In order to achieve the optimal background detrending technique for NPS estimate, four methods for artifactuals removal were quantitatively studied and compared: (1) Subtraction of a low-pass-filtered version of the image, (2) subtraction of a 2-D first-order fit to the image, (3) subtraction of a 2-D second-order polynomial fit to the image, and (4) subtracting two uniform exposure images. In addition, background trend removal was separately applied within original region of interest or its partitioned sub-blocks for all four methods. The performance of background detrending techniques was compared according to the statistical variance of the NPS results and low-frequency systematic rise suppression. Among four methods, subtraction of a 2-D second-order polynomial fit to the image was most effective in low-frequency systematic rise suppression and variances reduction for NPS estimate according to the authors' digital x-ray system. Subtraction of a low-pass-filtered version of the image led to NPS variance increment above low-frequency components because of the side lobe effects of frequency response of the boxcar filtering function. Subtracting two uniform exposure images obtained the worst result on the smoothness of NPS curve, although it was effective in low-frequency systematic rise suppression. Subtraction of a 2-D first-order fit to the image was also identified effective for background detrending, but it was worse than subtraction of a 2-D second-order polynomial fit to the image according to the authors' digital x-ray system. As a result of this study, the authors verified that it is necessary and feasible to get better NPS estimate by appropriate background trend removal. Subtraction of a 2-D second-order polynomial fit to the image was the most appropriate technique for background detrending without consideration of processing time.

Impulse Noise Cancellation of Medical Images Using Wavelet Networks and Median Filters

PubMed Central

Sadri, Amir Reza; Zekri, Maryam; Sadri, Saeid; Gheissari, Niloofar

2012-01-01

This paper presents a new two-stage approach to impulse noise removal for medical images based on wavelet network (WN). The first step is noise detection, in which the so-called gray-level difference and average background difference are considered as the inputs of a WN. Wavelet Network is used as a preprocessing for the second stage. The second step is removing impulse noise with a median filter. The wavelet network presented here is a fixed one without learning. Experimental results show that our method acts on impulse noise effectively, and at the same time preserves chromaticity and image details very well. PMID:23493998

A temporal and spatial analysis of anthropogenic noise sources affecting SNMR

NASA Astrophysics Data System (ADS)

Dalgaard, E.; Christiansen, P.; Larsen, J. J.; Auken, E.

2014-11-01

One of the biggest challenges when using the surface nuclear magnetic resonance (SNMR) method in urban areas is a relatively low signal level compared to a high level of background noise. To understand the temporal and spatial behavior of anthropogenic noise sources like powerlines and electric fences, we have developed a multichannel instrument, noiseCollector (nC), which measures the full noise spectrum up to 10 kHz. Combined with advanced signal processing we can interpret the noise as seen by a SNMR instrument and also obtain insight into the more fundamental behavior of the noise. To obtain a specified acceptable noise level for a SNMR sounding the stack size can be determined by quantifying the different noise sources. Two common noise sources, electromagnetic fields stemming from powerlines and fences are analyzed and show a 1/r2 dependency in agreement with theoretical relations. A typical noise map, obtained with the nC instrument prior to a SNMR field campaign, clearly shows the location of noise sources, and thus we can efficiently determine the optimal location for the SNMR sounding from a noise perspective.

Relationship between Speech Intelligibility and Speech Comprehension in Babble Noise

ERIC Educational Resources Information Center

Fontan, Lionel; Tardieu, Julien; Gaillard, Pascal; Woisard, Virginie; Ruiz, Robert

2015-01-01

Purpose: The authors investigated the relationship between the intelligibility and comprehension of speech presented in babble noise. Method: Forty participants listened to French imperative sentences (commands for moving objects) in a multitalker babble background for which intensity was experimentally controlled. Participants were instructed to…

Partial and Total Annoyance Due to Road Traffic Noise Combined with Aircraft or Railway Noise: Structural Equation Analysis.

PubMed

Gille, Laure-Anne; Marquis-Favre, Catherine; Lam, Kin-Che

2017-11-30

Structural equation modeling was used to analyze partial and total in situ annoyance in combined transportation noise situations. A psychophysical total annoyance model and a perceptual total annoyance model were proposed. Results show a high contribution of Noise exposure and Noise sensitivity to Noise annoyance , as well as a causal relationship between noise annoyance and lower Dwelling satisfaction. Moreover, the Visibility of noise source may increase noise annoyance, even when the visible noise source is different from the annoying source under study. With regards to total annoyance due to road traffic noise combined with railway or aircraft noise, even though in both situations road traffic noise may be considered background noise and the other noise source event noise, the contribution of road traffic noise to the models is greater than railway noise and smaller than aircraft noise. This finding may be explained by the difference in sound pressure levels between these two types of combined exposures or by the aircraft noise level, which may also indicate the city in which the respondents live. Finally, the results highlight the importance of sample size and variable distribution in the database, as different results can be observed depending on the sample or variables considered.

Partial and Total Annoyance Due to Road Traffic Noise Combined with Aircraft or Railway Noise: Structural Equation Analysis

PubMed Central

Gille, Laure-Anne; Marquis-Favre, Catherine; Lam, Kin-Che

2017-01-01

Structural equation modeling was used to analyze partial and total in situ annoyance in combined transportation noise situations. A psychophysical total annoyance model and a perceptual total annoyance model were proposed. Results show a high contribution of Noise exposure and Noise sensitivity to Noise annoyance, as well as a causal relationship between noise annoyance and lower Dwelling satisfaction. Moreover, the Visibility of noise source may increase noise annoyance, even when the visible noise source is different from the annoying source under study. With regards to total annoyance due to road traffic noise combined with railway or aircraft noise, even though in both situations road traffic noise may be considered background noise and the other noise source event noise, the contribution of road traffic noise to the models is greater than railway noise and smaller than aircraft noise. This finding may be explained by the difference in sound pressure levels between these two types of combined exposures or by the aircraft noise level, which may also indicate the city in which the respondents live. Finally, the results highlight the importance of sample size and variable distribution in the database, as different results can be observed depending on the sample or variables considered. PMID:29189751

The Effects of Hearing Aid Directional Microphone and Noise Reduction Processing on Listening Effort in Older Adults with Hearing Loss.

PubMed

Desjardins, Jamie L

2016-01-01

Older listeners with hearing loss may exert more cognitive resources to maintain a level of listening performance similar to that of younger listeners with normal hearing. Unfortunately, this increase in cognitive load, which is often conceptualized as increased listening effort, may come at the cost of cognitive processing resources that might otherwise be available for other tasks. The purpose of this study was to evaluate the independent and combined effects of a hearing aid directional microphone and a noise reduction (NR) algorithm on reducing the listening effort older listeners with hearing loss expend on a speech-in-noise task. Participants were fitted with study worn commercially available behind-the-ear hearing aids. Listening effort on a sentence recognition in noise task was measured using an objective auditory-visual dual-task paradigm. The primary task required participants to repeat sentences presented in quiet and in a four-talker babble. The secondary task was a digital visual pursuit rotor-tracking test, for which participants were instructed to use a computer mouse to track a moving target around an ellipse that was displayed on a computer screen. Each of the two tasks was presented separately and concurrently at a fixed overall speech recognition performance level of 50% correct with and without the directional microphone and/or the NR algorithm activated in the hearing aids. In addition, participants reported how effortful it was to listen to the sentences in quiet and in background noise in the different hearing aid listening conditions. Fifteen older listeners with mild sloping to severe sensorineural hearing loss participated in this study. Listening effort in background noise was significantly reduced with the directional microphones activated in the hearing aids. However, there was no significant change in listening effort with the hearing aid NR algorithm compared to no noise processing. Correlation analysis between objective and self-reported ratings of listening effort showed no significant relation. Directional microphone processing effectively reduced the cognitive load of listening to speech in background noise. This is significant because it is likely that listeners with hearing impairment will frequently encounter noisy speech in their everyday communications. American Academy of Audiology.

Frequency-Agile LIDAR Receiver for Chemical and Biological Agent Sensing

DTIC Science & Technology

2010-06-01

transimpedance preamplifier architecture was optimized around the selected IR detector diode – Input-referenced noise density of 0.8 nV/ Hz0.5  A portion of...objectives: • Reduce baseline (background) photon flux on detector : Tunable Fabry-Perot etalon in optical train • Reduce input-referenced amplifier noise ...custom amplifier • Reduce detector dark current: High impedance detector  Performance Metrics: – Noise equivalent power of receiver system (NEP

Geostatistical noise filtering of geophysical images : application to unexploded ordnance (UXO) sites.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saito, Hirotaka; McKenna, Sean Andrew; Coburn, Timothy C.

2004-07-01

Geostatistical and non-geostatistical noise filtering methodologies, factorial kriging and a low-pass filter, and a region growing method are applied to analytic signal magnetometer images at two UXO contaminated sites to delineate UXO target areas. Overall delineation performance is improved by removing background noise. Factorial kriging slightly outperforms the low-pass filter but there is no distinct difference between them in terms of finding anomalies of interest.

Reducing the Effects of Background Noise during Auditory Functional Magnetic Resonance Imaging of Speech Processing: Qualitative and Quantitative Comparisons between Two Image Acquisition Schemes and Noise Cancellation

ERIC Educational Resources Information Center

Blackman, Graham A.; Hall, Deborah A.

2011-01-01

Purpose: The intense sound generated during functional magnetic resonance imaging (fMRI) complicates studies of speech and hearing. This experiment evaluated the benefits of using active noise cancellation (ANC), which attenuates the level of the scanner sound at the participant's ear by up to 35 dB around the peak at 600 Hz. Method: Speech and…

Mobile videoconferencing for enhanced emergency medical communication - a shot in the dark or a walk in the park? ‒‒ A simulation study.

PubMed

Melbye, Sigurd; Hotvedt, Martin; Bolle, Stein Roald

2014-06-02

Videoconferencing on mobile phones may enhance communication, but knowledge on its quality in various situations is needed before it can be used in medical emergencies. Mobile phones automatically activate loudspeaker functionality during videoconferencing, making calls particularly vulnerable to background noise. The aim of this study was to investigate if videoconferencing can be used between lay bystanders and Emergency Medical Dispatch (EMD) operators for initial emergency calls during medical emergencies, under suboptimal sound and light conditions. Videoconferencing was tested between 90 volunteers and an emergency medical dispatcher in a standardized scenario of a medical emergency. Three different environments were used for the trials: indoors with moderate background noise, outdoors with daylight and much background noise, and outdoors during nighttime with little background noise. Thirty participants were recruited for each of the three locations. After informed consent, each participant was asked to use a video mobile phone to communicate with an EMD operator. During the video call the EMD operator gave instructions for tasks to be performed by the participant. The video quality from the caller to the EMD was evaluated by the EMD operator and rated on a five step scale ranging from "not able to see" to "good video quality". Sound quality between participants and EMD operators was assessed by a method developed for this trial. Kruskal - Wallis and Chi-square tests were used for statistical analysis. Video quality was significantly different between the groups (p <0.001), and the nighttime group had lower video quality. For most sessions in the nighttime group it was still possible to see actions done at the simulated emergency site. All participants were able to perform their tasks according to the instructions given by dispatchers, although with a need for more repetitions during sessions with much background noise. No calls were rated by dispatchers as incomprehensible due to low sound quality and only 3% of the calls were considered somewhat difficult or very difficult to understand. Videoconferencing on mobile phones can be used for the initial emergency call during medical emergencies also in suboptimal conditions.

The statistical mechanics of relativistic orbits around a massive black hole

NASA Astrophysics Data System (ADS)

Bar-Or, Ben; Alexander, Tal

2014-12-01

Stars around a massive black hole (MBH) move on nearly fixed Keplerian orbits, in a centrally-dominated potential. The random fluctuations of the discrete stellar background cause small potential perturbations, which accelerate the evolution of orbital angular momentum by resonant relaxation. This drives many phenomena near MBHs, such as extreme mass-ratio gravitational wave inspirals, the warping of accretion disks, and the formation of exotic stellar populations. We present here a formal statistical mechanics framework to analyze such systems, where the background potential is described as a correlated Gaussian noise. We derive the leading order, phase-averaged 3D stochastic Hamiltonian equations of motion, for evolving the orbital elements of a test star, and obtain the effective Fokker-Planck equation for a general correlated Gaussian noise, for evolving the stellar distribution function. We show that the evolution of angular momentum depends critically on the temporal smoothness of the background potential fluctuations. Smooth noise has a maximal variability frequency {{ν }max }. We show that in the presence of such noise, the evolution of the normalized angular momentum j=\\sqrt{1-{{e}2}} of a relativistic test star, undergoing Schwarzschild (in-plane) general relativistic precession with frequency {{ν }GR}/{{j}2}, is exponentially suppressed for j\\lt {{j}b}, where {{ν }GR}/jb2˜ {{ν }max }, due to the adiabatic invariance of the precession against the slowly varying random background torques. This results in an effective Schwarzschild precession-induced barrier in angular momentum. When jb is large enough, this barrier can have significant dynamical implications for processes near the MBH.

Influence of electronic apex locators and a gutta-percha heating device on implanted cardiac devices: an in vivo study.

PubMed

Moraes, A P; Silva, E J; Lamas, C C; Portugal, P H; Neves, A A

2016-06-01

To evaluate the potential for electromagnetic interference (EMI) of electronic apex locators (EALs) and a gutta-percha heating device (HD) in patients with implantable cardiac pacemakers (ICPs) or cardioverter-defibrillators (ICDs). Two types of EALs (Romiapex A-15 and Novapex) and a HD (Touch'n Heat) were tested in patients followed in an outpatient clinic for cardiac arrhythmias. The heart rhythm was monitored on a computer screen during all experimental phases. After baseline data collection, the patient held each appliance (turned on) for 30 s, simulating their clinical use. If background noise was detected on the cardiac monitor, the sensitivity of the ICP/ICD was lowered by the cardiologist to evaluate the intensity of the detected EMI. Twelve patients were evaluated (5 female and 7 male), and in nine instances, background noise in their cardiac devices related to the use of the endodontic devices was detected (6 patients). After lowering the sensitivity of the cardiac implants, three patients had more severe EMI in six instances, including pauses in ICP function. The presence of a symptomatic or asymptomatic pause was related to the patient's underlying heart rhythm. The HD device produced background noise more often compared to EALs. These were associated with more severe types of EMI. The EALs and gutta-percha HD were capable of causing background noise detection or pauses in cardiac implants in vivo. The use of electronic dental devices nearby patients with cardiac implants should be carefully considered in clinical practice. © 2015 International Endodontic Journal. Published by John Wiley & Sons Ltd.

Evaluation of the annoyance due to helicopter rotor noise

NASA Technical Reports Server (NTRS)

Sternfeld, H., Jr.; Doyle, L. B.

1978-01-01

A program was conducted in which 25 test subjects adjusted the levels of various helicopter rotor spectra until the combination of the harmonic noise and a broadband background noise was judged equally annoying as a higher level of the same broadband noise spectrum. The subjective measure of added harmonic noise was equated to the difference in the two levels of broadband noise. The test participants also made subjective evaluations of the rotor noise signatures which they created. The test stimuli consisted of three degrees of rotor impulsiveness, each presented at four blade passage rates. Each of these 12 harmonic sounds was combined with three broadband spectra and was adjusted to match the annoyance of three different sound pressure levels of broadband noise. Analysis of variance indicated that the important variables were level and impulsiveness. Regression analyses indicated that inclusion of crest factor improved correlation between the subjective measures and various objective or physical measures.

Influence of auditory fatigue on masked speech intelligibility

NASA Technical Reports Server (NTRS)

Parker, D. E.; Martens, W. L.; Johnston, P. A.

1980-01-01

Intelligibility of PB word lists embedded in simultaneous masking noise was evaluated before and after fatiguing-noise exposure, which was determined by observing the number of words correctly repeated during a shadowing task. Both the speech signal and the masking noise were filtered to a 2825-3185-Hz band. Masking-noise leves were varied from 0- to 90-dB SL. Fatigue was produced by a 1500-3000-Hz octave band of noise at 115 dB (re 20 micron-Pa) presented continuously for 5 min. The results of three experiments indicated that speed intelligibility was reduced when the speech was presented against a background of silence but that the fatiguing-noise exposure had no effect on intelligibility when the speech was made more intense and embedded in masking noise of 40-90-dB SL. These observations are interpreted by considering the recruitment produced by fatigue and masking noise.

Evaluation of the risk of noise-induced hearing loss among unscreened male industrial workers.

PubMed

Prince, Mary M; Gilbert, Stephen J; Smith, Randall J; Stayner, Leslie T

2003-02-01

Variability in background risk and distribution of various risk factors for hearing loss may explain some of the diversity in excess risk of noise-induced hearing loss (NIHL). This paper examines the impact of various risk factors on excess risk estimates of NIHL using data from the 1968-1972 NIOSH Occupational Noise and Hearing Survey (ONHS). Previous analyses of a subset of these data focused on 1172 highly "screened" workers. In the current analysis, an additional 894 white males (609 noise-exposed and 285 controls), who were excluded for various reasons (i.e., nonoccupational noise exposure, otologic or medical conditions affecting hearing, prior occupational noise exposure) have been added 2066) to assess excess risk of noise-induced material impairment in an unscreened population. Data are analyzed by age, duration of exposure, and sound level (8-h TWA) for four different definitions of noise-induced hearing impairment, defined as the binaural pure-tone average (PTA) hearing threshold level greater than 25 dB for the following frequencies: (a) 1-4 kHz (PTA1234), (b) 1-3 kHz (PTA123), (c) 0.5, 1, and 2 kHz (PTA512), and (d) 3, 4, and 6 kHz (PTA346). Results indicate that populations with higher background risks of hearing loss may show lower excess risks attributable to noise relative to highly screened populations. Estimates of lifetime excess risk of hearing impairment were found to be significantly different between screened and unscreened population for noise levels greater than 90 dBA. Predicted age-related risk of material hearing impairment in the ONHS unscreened population was similar to that predicted from Annex B and C of ANSI S3.44 for ages less than 60 years. Results underscore the importance of understanding differential risk patterns for hearing loss and the use of appropriate reference (control) populations when evaluating risk of noise-induced hearing impairment among contemporary industrial populations.

Musicians change their tune: how hearing loss alters the neural code.

PubMed

Parbery-Clark, Alexandra; Anderson, Samira; Kraus, Nina

2013-08-01

Individuals with sensorineural hearing loss have difficulty understanding speech, especially in background noise. This deficit remains even when audibility is restored through amplification, suggesting that mechanisms beyond a reduction in peripheral sensitivity contribute to the perceptual difficulties associated with hearing loss. Given that normal-hearing musicians have enhanced auditory perceptual skills, including speech-in-noise perception, coupled with heightened subcortical responses to speech, we aimed to determine whether similar advantages could be observed in middle-aged adults with hearing loss. Results indicate that musicians with hearing loss, despite self-perceptions of average performance for understanding speech in noise, have a greater ability to hear in noise relative to nonmusicians. This is accompanied by more robust subcortical encoding of sound (e.g., stimulus-to-response correlations and response consistency) as well as more resilient neural responses to speech in the presence of background noise (e.g., neural timing). Musicians with hearing loss also demonstrate unique neural signatures of spectral encoding relative to nonmusicians: enhanced neural encoding of the speech-sound's fundamental frequency but not of its upper harmonics. This stands in contrast to previous outcomes in normal-hearing musicians, who have enhanced encoding of the harmonics but not the fundamental frequency. Taken together, our data suggest that although hearing loss modifies a musician's spectral encoding of speech, the musician advantage for perceiving speech in noise persists in a hearing-impaired population by adaptively strengthening underlying neural mechanisms for speech-in-noise perception. Copyright © 2013 Elsevier B.V. All rights reserved.

Evaluation of noise limits to improve image processing in soft X-ray projection microscopy.

PubMed

Jamsranjav, Erdenetogtokh; Kuge, Kenichi; Ito, Atsushi; Kinjo, Yasuhito; Shiina, Tatsuo

2017-03-03

Soft X-ray microscopy has been developed for high resolution imaging of hydrated biological specimens due to the availability of water window region. In particular, a projection type microscopy has advantages in wide viewing area, easy zooming function and easy extensibility to computed tomography (CT). The blur of projection image due to the Fresnel diffraction of X-rays, which eventually reduces spatial resolution, could be corrected by an iteration procedure, i.e., repetition of Fresnel and inverse Fresnel transformations. However, it was found that the correction is not enough to be effective for all images, especially for images with low contrast. In order to improve the effectiveness of image correction by computer processing, we in this study evaluated the influence of background noise in the iteration procedure through a simulation study. In the study, images of model specimen with known morphology were used as a substitute for the chromosome images, one of the targets of our microscope. Under the condition that artificial noise was distributed on the images randomly, we introduced two different parameters to evaluate noise effects according to each situation where the iteration procedure was not successful, and proposed an upper limit of the noise within which the effective iteration procedure for the chromosome images was possible. The study indicated that applying the new simulation and noise evaluation method was useful for image processing where background noises cannot be ignored compared with specimen images.

A New Statistical Model of Electroencephalogram Noise Spectra for Real-Time Brain-Computer Interfaces.

PubMed

Paris, Alan; Atia, George K; Vosoughi, Azadeh; Berman, Stephen A

2017-08-01

A characteristic of neurological signal processing is high levels of noise from subcellular ion channels up to whole-brain processes. In this paper, we propose a new model of electroencephalogram (EEG) background periodograms, based on a family of functions which we call generalized van der Ziel-McWhorter (GVZM) power spectral densities (PSDs). To the best of our knowledge, the GVZM PSD function is the only EEG noise model that has relatively few parameters, matches recorded EEG PSD's with high accuracy from 0 to over 30 Hz, and has approximately 1/f θ behavior in the midfrequencies without infinities. We validate this model using three approaches. First, we show how GVZM PSDs can arise in a population of ion channels at maximum entropy equilibrium. Second, we present a class of mixed autoregressive models, which simulate brain background noise and whose periodograms are asymptotic to the GVZM PSD. Third, we present two real-time estimation algorithms for steady-state visual evoked potential (SSVEP) frequencies, and analyze their performance statistically. In pairwise comparisons, the GVZM-based algorithms showed statistically significant accuracy improvement over two well-known and widely used SSVEP estimators. The GVZM noise model can be a useful and reliable technique for EEG signal processing. Understanding EEG noise is essential for EEG-based neurology and applications such as real-time brain-computer interfaces, which must make accurate control decisions from very short data epochs. The GVZM approach represents a successful new paradigm for understanding and managing this neurological noise.

Objective speech quality assessment and the RPE-LTP coding algorithm in different noise and language conditions.

PubMed

Hansen, J H; Nandkumar, S

1995-01-01

The formulation of reliable signal processing algorithms for speech coding and synthesis require the selection of a prior criterion of performance. Though coding efficiency (bits/second) or computational requirements can be used, a final performance measure must always include speech quality. In this paper, three objective speech quality measures are considered with respect to quality assessment for American English, noisy American English, and noise-free versions of seven languages. The purpose is to determine whether objective quality measures can be used to quantify changes in quality for a given voice coding method, with a known subjective performance level, as background noise or language conditions are changed. The speech coding algorithm chosen is regular-pulse excitation with long-term prediction (RPE-LTP), which has been chosen as the standard voice compression algorithm for the European Digital Mobile Radio system. Three areas are considered for objective quality assessment which include: (i) vocoder performance for American English in a noise-free environment, (ii) speech quality variation for three additive background noise sources, and (iii) noise-free performance for seven languages which include English, Japanese, Finnish, German, Hindi, Spanish, and French. It is suggested that although existing objective quality measures will never replace subjective testing, they can be a useful means of assessing changes in performance, identifying areas for improvement in algorithm design, and augmenting subjective quality tests for voice coding/compression algorithms in noise-free, noisy, and/or non-English applications.

Active Noise Control for Dishwasher noise

NASA Astrophysics Data System (ADS)

Lee, Nokhaeng; Park, Youngjin

2016-09-01

The dishwasher is a useful home appliance and continually used for automatically washing dishes. It's commonly placed in the kitchen with built-in style for practicality and better use of space. In this environment, people are easily exposed to dishwasher noise, so it is an important issue for the consumers, especially for the people living in open and narrow space. Recently, the sound power levels of the noise are about 40 - 50 dBA. It could be achieved by removal of noise sources and passive means of insulating acoustical path. For more reduction, such a quiet mode with the lower speed of cycle has been introduced, but this deteriorates the washing capacity. Under this background, we propose active noise control for dishwasher noise. It is observed that the noise is propagating mainly from the lower part of the front side. Control speakers are placed in the part for the collocation. Observation part of estimating sound field distribution and control part of generating the anti-noise are designed for active noise control. Simulation result shows proposed active noise control scheme could have a potential application for dishwasher noise reduction.

A pilot study of human response to general aviation aircraft noise

NASA Technical Reports Server (NTRS)

Stearns, J.; Brown, R.; Neiswander, P.

1983-01-01

A pilot study, conducted to evaluate procedures for measuring the noise impact and community response to general aviation aircraft around Torrance Municipal Airport, a typical large GA airport, employed Torrance Airport's computer-based aircraft noise monitoring system, which includes nine permanent monitor stations surrounding the airport. Some 18 residences near these monitor stations were equipped with digital noise level recorders to measure indoor noise levels. Residents were instructed to fill out annoyance diaries for periods of 5-6 days, logging the time of each annoying aircraft overflight noise event and judging its degree of annoyance on a seven-point scale. Among the noise metrics studied, the differential between outdoor maximum A-weighted noise level of the aircraft and the outdoor background level showed the best correlation with annoyance; this correlation was clearly seen at only high noise levels, And was only slightly better than that using outdoor aircraft noise level alone. The results indicate that, on a national basis, a telephone survey coupled with outdoor noise measurements would provide an efficient and practical means of assessing the noise impact of general aviation aircraft.

Audio-Visual Speech in Noise Perception in Dyslexia

ERIC Educational Resources Information Center

van Laarhoven, Thijs; Keetels, Mirjam; Schakel, Lemmy; Vroomen, Jean

2018-01-01

Individuals with developmental dyslexia (DD) may experience, besides reading problems, other speech-related processing deficits. Here, we examined the influence of visual articulatory information (lip-read speech) at various levels of background noise on auditory word recognition in children and adults with DD. We found that children with a…

Sensory Biology: How Female Treefrogs Pick Mates at a Noisy Party.

PubMed

Taylor, Ryan C

2017-03-06

A recent study has found that, despite strong acoustic masking from background noise, female treefrogs are able to select among individual males advertising for mates by taking advantage of small, periodic decreases in the overall noise structure. Copyright © 2017 Elsevier Ltd. All rights reserved.

Noise and Hearing Loss: A Review

ERIC Educational Resources Information Center

Daniel, Eileen

2007-01-01

Background: Noise-induced hearing loss is a major cause of deafness and hearing impairment in the United States. Though genetics and advanced age are major risk factors, temporary and permanent hearing impairments are becoming more common among young adults and children especially with the increased exposure to portable music players. Though…

Associations of Short-Term Particle and Noise Exposures with Markers of Cardiovascular and Respiratory Health among Highway Maintenance Workers

EPA Science Inventory

Background: Highway maintenance workers are constantly and simultaneously exposed to traffic-related particle and noise emissions, and both have been linked to increased cardiovascular morbidity and mortality in population-based epidemiology studies. Objectives: We aimed to in...

Motion artifact and background noise suppression on optical microangiography frames using a naïve Bayes mask.

PubMed

Reif, Roberto; Baran, Utku; Wang, Ruikang K

2014-07-01

Optical coherence tomography (OCT) is a technique that allows for the three-dimensional (3D) imaging of small volumes of tissue (a few millimeters) with high resolution (∼10  μm). Optical microangiography (OMAG) is a method of processing OCT data, which allows for the extraction of the tissue vasculature with capillary resolution from the OCT images. Cross-sectional B-frame OMAG images present the location of the patent blood vessels; however, the signal-to-noise-ratio of these images can be affected by several factors such as the quality of the OCT system and the tissue motion artifact. This background noise can appear in the en face projection view image. In this work we propose to develop a binary mask that can be applied on the cross-sectional B-frame OMAG images, which will reduce the background noise while leaving the signal from the blood vessels intact. The mask is created by using a naïve Bayes (NB) classification algorithm trained with a gold standard image which is manually segmented by an expert. The masked OMAG images present better contrast for binarizing the image and quantifying the result without the influence of noise. The results are compared with a previously developed frequency rejection filter (FRF) method which is applied on the en face projection view image. It is demonstrated that both the NB and FRF methods provide similar vessel length fractions. The advantage of the NB method is that the results are applicable in 3D and that its use is not limited to periodic motion artifacts.

Auditory Processing in Noise Is Associated With Complex Patterns of Disrupted Functional Connectivity in Autism Spectrum Disorder

PubMed Central

Mamashli, Fahimeh; Khan, Sheraz; Bharadwaj, Hari; Michmizos, Konstantinos; Ganesan, Santosh; Garel, Keri-Lee A.; Hashmi, Javeria Ali; Herbert, Martha R.; Hämäläinen, Matti; Kenet, Tal

2017-01-01

Autism spectrum disorder (ASD) is associated with difficulty in processing speech in a noisy background, but the neural mechanisms that underlie this deficit have not been mapped. To address this question, we used magnetoencephalography to compare the cortical responses between ASD and typically developing (TD) individuals to a passive mismatch paradigm. We repeated the paradigm twice, once in a quiet background, and once in the presence of background noise. We focused on both the evoked mismatch field (MMF) response in temporal and frontal cortical locations, and functional connectivity with spectral specificity between those locations. In the quiet condition, we found common neural sources of the MMF response in both groups, in the right temporal gyrus and inferior frontal gyrus (IFG). In the noise condition, the MMF response in the right IFG was preserved in the TD group, but reduced relative to the quiet condition in ASD group. The MMF response in the right IFG also correlated with severity of ASD. Moreover, in noise, we found significantly reduced normalized coherence (deviant normalized by standard) in ASD relative to TD, in the beta band (14–25 Hz), between left temporal and left inferior frontal sub-regions. However, unnormalized coherence (coherence during deviant or standard) was significantly increased in ASD relative to TD, in multiple frequency bands. Our findings suggest increased recruitment of neural resources in ASD irrespective of the task difficulty, alongside a reduction in top-down modulations, usually mediated by the beta band, needed to mitigate the impact of noise on auditory processing. PMID:27910247

Homebuilt single-molecule scanning confocal fluorescence microscope studies of single DNA/protein interactions.

PubMed

Zheng, Haocheng; Goldner, Lori S; Leuba, Sanford H

2007-03-01

Many technical improvements in fluorescence microscopy over the years have focused on decreasing background and increasing the signal to noise ratio (SNR). The scanning confocal fluorescence microscope (SCFM) represented a major improvement in these efforts. The SCFM acquires signal from a thin layer of a thick sample, rejecting light whose origin is not in the focal plane thereby dramatically decreasing the background signal. A second major innovation was the advent of high quantum-yield, low noise, single-photon counting detectors. The superior background rejection of SCFM combined with low-noise, high-yield detectors makes it possible to detect the fluorescence from single-dye molecules. By labeling a DNA molecule or a DNA/protein complex with a donor/acceptor dye pair, fluorescence resonance energy transfer (FRET) can be used to track conformational changes in the molecule/complex itself, on a single molecule/complex basis. In this methods paper, we describe the core concepts of SCFM in the context of a study that uses FRET to reveal conformational fluctuations in individual Holliday junction DNA molecules and nucleosomal particles. We also discuss data processing methods for SCFM.

Bayesian Analysis of the Cosmic Microwave Background

NASA Technical Reports Server (NTRS)

Jewell, Jeffrey

2007-01-01

There is a wealth of cosmological information encoded in the spatial power spectrum of temperature anisotropies of the cosmic microwave background! Experiments designed to map the microwave sky are returning a flood of data (time streams of instrument response as a beam is swept over the sky) at several different frequencies (from 30 to 900 GHz), all with different resolutions and noise properties. The resulting analysis challenge is to estimate, and quantify our uncertainty in, the spatial power spectrum of the cosmic microwave background given the complexities of "missing data", foreground emission, and complicated instrumental noise. Bayesian formulation of this problem allows consistent treatment of many complexities including complicated instrumental noise and foregrounds, and can be numerically implemented with Gibbs sampling. Gibbs sampling has now been validated as an efficient, statistically exact, and practically useful method for low-resolution (as demonstrated on WMAP 1 and 3 year temperature and polarization data). Continuing development for Planck - the goal is to exploit the unique capabilities of Gibbs sampling to directly propagate uncertainties in both foreground and instrument models to total uncertainty in cosmological parameters.

Speech Enhancement based on the Dominant Classification Between Speech and Noise Using Feature Data in Spectrogram of Observation Signal

NASA Astrophysics Data System (ADS)

Nomura, Yukihiro; Lu, Jianming; Sekiya, Hiroo; Yahagi, Takashi

This paper presents a speech enhancement using the classification between the dominants of speech and noise. In our system, a new classification scheme between the dominants of speech and noise is proposed. The proposed classifications use the standard deviation of the spectrum of observation signal in each band. We introduce two oversubtraction factors for the dominants of speech and noise, respectively. And spectral subtraction is carried out after the classification. The proposed method is tested on several noise types from the Noisex-92 database. From the investigation of segmental SNR, Itakura-Saito distance measure, inspection of spectrograms and listening tests, the proposed system is shown to be effective to reduce background noise. Moreover, the enhanced speech using our system generates less musical noise and distortion than that of conventional systems.

Solutions to the Cocktail Party Problem in Insects: Selective Filters, Spatial Release from Masking and Gain Control in Tropical Crickets

PubMed Central

Schmidt, Arne K. D.; Römer, Heiner

2011-01-01

Background Insects often communicate by sound in mixed species choruses; like humans and many vertebrates in crowded social environments they thus have to solve cocktail-party-like problems in order to ensure successful communication with conspecifics. This is even more a problem in species-rich environments like tropical rainforests, where background noise levels of up to 60 dB SPL have been measured. Principal Findings Using neurophysiological methods we investigated the effect of natural background noise (masker) on signal detection thresholds in two tropical cricket species Paroecanthus podagrosus and Diatrypa sp., both in the laboratory and outdoors. We identified three ‘bottom-up’ mechanisms which contribute to an excellent neuronal representation of conspecific signals despite the masking background. First, the sharply tuned frequency selectivity of the receiver reduces the amount of masking energy around the species-specific calling song frequency. Laboratory experiments yielded an average signal-to-noise ratio (SNR) of −8 dB, when masker and signal were broadcast from the same side. Secondly, displacing the masker by 180° from the signal improved SNRs by further 6 to 9 dB, a phenomenon known as spatial release from masking. Surprisingly, experiments carried out directly in the nocturnal rainforest yielded SNRs of about −23 dB compared with those in the laboratory with the same masker, where SNRs reached only −14.5 and −16 dB in both species. Finally, a neuronal gain control mechanism enhances the contrast between the responses to signals and the masker, by inhibition of neuronal activity in interstimulus intervals. Conclusions Thus, conventional speaker playbacks in the lab apparently do not properly reconstruct the masking noise situation in a spatially realistic manner, since under real world conditions multiple sound sources are spatially distributed in space. Our results also indicate that without knowledge of the receiver properties and the spatial release mechanisms the detrimental effect of noise may be strongly overestimated. PMID:22163041

Speech Processing to Improve the Perception of Speech in Background Noise for Children With Auditory Processing Disorder and Typically Developing Peers.

PubMed

Flanagan, Sheila; Zorilă, Tudor-Cătălin; Stylianou, Yannis; Moore, Brian C J

2018-01-01

Auditory processing disorder (APD) may be diagnosed when a child has listening difficulties but has normal audiometric thresholds. For adults with normal hearing and with mild-to-moderate hearing impairment, an algorithm called spectral shaping with dynamic range compression (SSDRC) has been shown to increase the intelligibility of speech when background noise is added after the processing. Here, we assessed the effect of such processing using 8 children with APD and 10 age-matched control children. The loudness of the processed and unprocessed sentences was matched using a loudness model. The task was to repeat back sentences produced by a female speaker when presented with either speech-shaped noise (SSN) or a male competing speaker (CS) at two signal-to-background ratios (SBRs). Speech identification was significantly better with SSDRC processing than without, for both groups. The benefit of SSDRC processing was greater for the SSN than for the CS background. For the SSN, scores were similar for the two groups at both SBRs. For the CS, the APD group performed significantly more poorly than the control group. The overall improvement produced by SSDRC processing could be useful for enhancing communication in a classroom where the teacher's voice is broadcast using a wireless system.

Masked speech perception across the adult lifespan: Impact of age and hearing impairment.

PubMed

Goossens, Tine; Vercammen, Charlotte; Wouters, Jan; van Wieringen, Astrid

2017-02-01

As people grow older, speech perception difficulties become highly prevalent, especially in noisy listening situations. Moreover, it is assumed that speech intelligibility is more affected in the event of background noises that induce a higher cognitive load, i.e., noises that result in informational versus energetic masking. There is ample evidence showing that speech perception problems in aging persons are partly due to hearing impairment and partly due to age-related declines in cognition and suprathreshold auditory processing. In order to develop effective rehabilitation strategies, it is indispensable to know how these different degrading factors act upon speech perception. This implies disentangling effects of hearing impairment versus age and examining the interplay between both factors in different background noises of everyday settings. To that end, we investigated open-set sentence identification in six participant groups: a young (20-30 years), middle-aged (50-60 years), and older cohort (70-80 years), each including persons who had normal audiometric thresholds up to at least 4 kHz, on the one hand, and persons who were diagnosed with elevated audiometric thresholds, on the other hand. All participants were screened for (mild) cognitive impairment. We applied stationary and amplitude modulated speech-weighted noise, which are two types of energetic maskers, and unintelligible speech, which causes informational masking in addition to energetic masking. By means of these different background noises, we could look into speech perception performance in listening situations with a low and high cognitive load, respectively. Our results indicate that, even when audiometric thresholds are within normal limits up to 4 kHz, irrespective of threshold elevations at higher frequencies, and there is no indication of even mild cognitive impairment, masked speech perception declines by middle age and decreases further on to older age. The impact of hearing impairment is as detrimental for young and middle-aged as it is for older adults. When the background noise becomes cognitively more demanding, there is a larger decline in speech perception, due to age or hearing impairment. Hearing impairment seems to be the main factor underlying speech perception problems in background noises that cause energetic masking. However, in the event of informational masking, which induces a higher cognitive load, age appears to explain a significant part of the communicative impairment as well. We suggest that the degrading effect of age is mediated by deficiencies in temporal processing and central executive functions. This study may contribute to the improvement of auditory rehabilitation programs aiming to prevent aging persons from missing out on conversations, which, in turn, will improve their quality of life. Copyright © 2016 Elsevier B.V. All rights reserved.

The Analysis and Suppression of the spike noise in vibrator record

NASA Astrophysics Data System (ADS)

Jia, H.; Jiang, T.; Xu, X.; Ge, L.; Lin, J.; Yang, Z.

2013-12-01

During the seismic exploration with vibrator, seismic recording systems have often been affected by random spike noise in the background, which leads to strong data distortions as a result of the cross-correlation processing of the vibrator method. Partial or total loss of the desired seismic information is possible if no automatic spike reduction is available in the field prior to correlation of the field record. Generally speaking, original record of vibrator is uncorrelated data, in which the signal is non-wavelet form. In order to obtain the seismic record similar to explosive source, the signal of uncorrelated data needs to use the correlation algorithm to compress into wavelet form. The correlation process results in that the interference of spike in correlated data is not only being suppressed, but also being expanded. So the spike noise suppression of vibrator is indispensable. According to numerical simulation results, the effect of spike in the vibrator record is mainly affected by the amplitude and proportional points in the uncorrelated record. When the spike noise ratio in uncorrelated record reaches 1.5% and the average amplitude exceeds 200, it will make the SNR(signal-to-noise ratio) of the correlated record lower than 0dB, so that it is difficult to separate the signal. While the amplitude and ratio is determined by the intensity of background noise. Therefore, when the noise level is strong, in order to improve SNR of the seismic data, the uncorrelated record of vibrator need to take necessary steps to suppress spike noise. For the sake of reducing the influence of the spike noise, we need to make the detection and suppression of spike noise process for the uncorrelated record. Because vibrator works by inputting sweep signal into the underground long time, ideally, the peak and valley values of each trace have little change. On the basis of the peak and valley values, we can get a reference amplitude value. Then the spike can be detected and suppressed. After this process, it can reduce the effection of spike noise in the uncorrelated record to improve the SNR. At present, because the memory space of vibrator uncorrelated data is always very large, in order to reduce acquisition costs, we usually record correlated data directly. It's reasonable if there is no strong spike sneaking into uncorrelated record. However, due to the fact that the random spike in the background is not avoidable in the acquisition process, and the instantaneous input energy of the vibrator is probably smaller than spike noise, which makes the uncorrelated data contain a certain amount of spike noise, it severely reduces the acquisition quality of vibrator if there is no noise suppression module beforehand. Of course, the suppressing process of spike noise can be carried out in the field acquisition or data processing stage. In the field of vibrator acquisition system, we can use the spike noise suppression before the correlated module, so that it can directly record correlated data without the spike affection. If in the stage of data processing, it is necessary to record uncorrelated data.

Secretary of the Navy, Processor of Oceanography

DTIC Science & Technology

2009-07-20

earliest days of SOFAR transmissions. We proposed that scattering from internal waves could account for the penetration, and this has now been confirmed...related to change in obliquity (C2). D. Acoustic Noise generated by Ocean Waves . Farrell and I have found that the acoustic noise background in the...deep ocean down to 5 km is associated with short surface waves . There is some evidence for a noise minimum centered at 27 Hz (Dl, D2). This might be

Quantum limited performance of optical receivers

NASA Astrophysics Data System (ADS)

Farrell, Thomas C.

2018-05-01

While the fundamental performance limit for traditional radio frequency (RF) communications is often set by background noise on the channel, the fundamental limit for optical communications is set by the quantum nature of light. Both types of systems are based on electro-magnetic waves, differing only in carrier frequency. It is, in fact, the frequency that determines which of these limits dominates. We explore this in the first part of this paper. This leads to a difference in methods of analysis of the two different types of systems. While equations predicting the probability of bit error for RF systems are usually based on the signal to background noise ratio, similar equations for optical systems are often based on the physics of the quantum limit and are simply a function of the detected signal energy received per bit. These equations are derived in the second part of this paper for several frequently used modulation schemes: On-off keying (OOK), pulse position modulation (PPM), and binary differential phase shift keying (DPSK). While these equations ignore the effects of background noise and non-quantum internal noise sources in the detector and receiver electronics, they provide a useful bound for obtainable performance of optical communication systems. For example, these equations may be used in initial link budgets to assess the feasibility of system architectures, even before specific receiver designs are considered.

Angiotensin-converting enzyme gene polymorphisms and hypertension in occupational noise exposure in Egypt

PubMed Central

Zawilla, Nermin; Shaker, Dalia; Abdelaal, Amaal; Aref, Wael

2014-01-01

Background: The gene–environment interaction in the pathogenesis of hypertension has not been extensively studied in occupational noise. Objectives: The aim of this study was to determine the relationship between noise and hypertension in Egyptian workers, the interaction of angiotensin-converting enzyme (ACE) gene polymorphisms as modifiers, and the possible relationship between noise hearing impairment and hypertension. Methods: Study subjects were divided into two groups depending on noise exposure level. The control group (n = 161) was exposed to noise intensity <85 dB and the exposed group (n = 217) was exposed to noise intensity ≧85 dB. A polymerase chain reaction was used to differentiate the various genotypes of ACE insertion/deletion (I/D) and ACE G2350A. Results: Noise significantly increased the likelihood of hypertension. Carriers of the genotypes AG, GG, and DD were vulnerable to hypertension on noise exposure. No association between hypertension and hearing impairment or noise-induced hearing loss (NIHL) was found. Conclusion: Our results support the association between ACE gene polymorphisms and occurrence of hypertension in noise-exposed workers. PMID:25000107

Conductivity noise in transmembrane ion channels due to ion concentration fluctuations via diffusion.

PubMed

Mak, D O; Webb, W W

1997-03-01

A Green's function approach is developed from first principles to evaluate the power spectral density of conductance fluctuations caused by ion concentration fluctuations via diffusion in an electrolyte system. This is applied to simple geometric models of transmembrane ion channels to obtain an estimate of the magnitude of ion concentration fluctuation noise in the channel current. Pure polypeptide alamethicin forms stable ion channels with multiple conductance states in artificial phospholipid bilayers isolated onto tips of micropipettes with gigaohm seals. In the single-channel current recorded by voltage-clamp techniques, excess noise was found after the background instrumental noise and the intrinsic Johnson and shot noises were removed. The noise que to ion concentration fluctuations via diffusion was isolated by the dependence of the excess current noise on buffer ion concentration. The magnitude of the concentration fluctuation noise derived from experimental data lies within limits estimated using our simple geometric channel models. Variation of the noise magnitude for alamethicin channels in various conductance states agrees with theoretical prediction.

Noise pollution is pervasive in U.S. protected areas.

PubMed

Buxton, Rachel T; McKenna, Megan F; Mennitt, Daniel; Fristrup, Kurt; Crooks, Kevin; Angeloni, Lisa; Wittemyer, George

2017-05-05

Anthropogenic noise threatens ecological systems, including the cultural and biodiversity resources in protected areas. Using continental-scale sound models, we found that anthropogenic noise doubled background sound levels in 63% of U.S. protected area units and caused a 10-fold or greater increase in 21%, surpassing levels known to interfere with human visitor experience and disrupt wildlife behavior, fitness, and community composition. Elevated noise was also found in critical habitats of endangered species, with 14% experiencing a 10-fold increase in sound levels. However, protected areas with more stringent regulations had less anthropogenic noise. Our analysis indicates that noise pollution in protected areas is closely linked with transportation, development, and extractive land use, providing insight into where mitigation efforts can be most effective. Copyright © 2017, American Association for the Advancement of Science.

Performance of charge-injection-device infrared detector arrays at low and moderate backgrounds

NASA Technical Reports Server (NTRS)

Mckelvey, M. E.; Mccreight, C. R.; Goebel, J. H.; Reeves, A. A.

1985-01-01

Three 2 x 64 element charge injection device infrared detector arrays were tested at low and moderate background to evaluate their usefulness for space based astronomical observations. Testing was conducted both in the laboratory and in ground based telescope observations. The devices showed an average readout noise level below 200 equivalent electrons, a peak responsivity of 4 A/W, and a noise equivalent power of 3x10 sq root of W/Hz. Array well capacity was measured to be significantly smaller than predicted. The measured sensitivity, which compares well with that of nonintegrating discrete extrinsic silicon photoconductors, shows these arrays to be useful for certain astronomical observations. However, the measured readout efficiency and frequency response represent serious limitations in low background applications.

49 CFR 227.109 - Audiometric testing program.

Code of Federal Regulations, 2011 CFR

2011-10-01

...) Measurements of background sound pressure levels in the audiometric test room as required in appendix D of this... occupational noise in excess of the action level. Hearing protectors may be used as a substitute for the... railroad shall notify its employees of the need to avoid high levels of non-occupational noise exposure...

Comparative efficiency of a scheme of cyclic alternating-period subtraction

NASA Astrophysics Data System (ADS)

Golikov, V. S.; Artemenko, I. G.; Malinin, A. P.

1986-06-01

The estimation of the detection quality of a signal on a background of correlated noise according to the Neumann-Pearson criterion is examined. It is shown that, in a number of cases, the cyclic alternating-period subtraction scheme has a higher noise immunity than the conventional alternating-period subtraction scheme.

Listeners Experience Linguistic Masking Release in Noise-Vocoded Speech-in-Speech Recognition

ERIC Educational Resources Information Center

Viswanathan, Navin; Kokkinakis, Kostas; Williams, Brittany T.

2018-01-01

Purpose: The purpose of this study was to evaluate whether listeners with normal hearing perceiving noise-vocoded speech-in-speech demonstrate better intelligibility of target speech when the background speech was mismatched in language (linguistic release from masking [LRM]) and/or location (spatial release from masking [SRM]) relative to the…

Acquiring L2 Sentence Comprehension: A Longitudinal Study of Word Monitoring in Noise

ERIC Educational Resources Information Center

Oliver, Georgina; Gullberg, Marianne; Hellwig, Frauke; Mitterer, Holger; Indefrey, Peter

2012-01-01

This study investigated the development of second language online auditory processing with ab initio German learners of Dutch. We assessed the influence of different levels of background noise and different levels of semantic and syntactic target word predictability on word-monitoring latencies. There was evidence of syntactic, but not…

A Psychophysical Test of the Visual Pathway of Children with Autism

ERIC Educational Resources Information Center

Sanchez-Marin, Francisco J.; Padilla-Medina, Jose A.

2008-01-01

Signal detection psychophysical experiments were conducted to investigate the visual path of children with autism. Computer generated images with Gaussian noise were used. Simple signals, still and in motion were embedded in the background noise. The computer monitor was linearized to properly display the contrast changes. To our knowledge, this…

Estimation of neural energy in microelectrode signals

NASA Astrophysics Data System (ADS)

Gaumond, R. P.; Clement, R.; Silva, R.; Sander, D.

2004-09-01

We considered the problem of determining the neural contribution to the signal recorded by an intracortical electrode. We developed a linear least-squares approach to determine the energy fraction of a signal attributable to an arbitrary number of autocorrelation-defined signals buried in noise. Application of the method requires estimation of autocorrelation functions Rap(tgr) characterizing the action potential (AP) waveforms and Rn(tgr) characterizing background noise. This method was applied to the analysis of chronically implanted microelectrode signals from motor cortex of rat. We found that neural (AP) energy consisted of a large-signal component which grows linearly with the number of threshold-detected neural events and a small-signal component unrelated to the count of threshold-detected AP signals. The addition of pseudorandom noise to electrode signals demonstrated the algorithm's effectiveness for a wide range of noise-to-signal energy ratios (0.08 to 39). We suggest, therefore, that the method could be of use in providing a measure of neural response in situations where clearly identified spike waveforms cannot be isolated, or in providing an additional 'background' measure of microelectrode neural activity to supplement the traditional AP spike count.

Implementation and performance evaluation of acoustic denoising algorithms for UAV

NASA Astrophysics Data System (ADS)

Chowdhury, Ahmed Sony Kamal

Unmanned Aerial Vehicles (UAVs) have become popular alternative for wildlife monitoring and border surveillance applications. Elimination of the UAV's background noise and classifying the target audio signal effectively are still a major challenge. The main goal of this thesis is to remove UAV's background noise by means of acoustic denoising techniques. Existing denoising algorithms, such as Adaptive Least Mean Square (LMS), Wavelet Denoising, Time-Frequency Block Thresholding, and Wiener Filter, were implemented and their performance evaluated. The denoising algorithms were evaluated for average Signal to Noise Ratio (SNR), Segmental SNR (SSNR), Log Likelihood Ratio (LLR), and Log Spectral Distance (LSD) metrics. To evaluate the effectiveness of the denoising algorithms on classification of target audio, we implemented Support Vector Machine (SVM) and Naive Bayes classification algorithms. Simulation results demonstrate that LMS and Discrete Wavelet Transform (DWT) denoising algorithm offered superior performance than other algorithms. Finally, we implemented the LMS and DWT algorithms on a DSP board for hardware evaluation. Experimental results showed that LMS algorithm's performance is robust compared to DWT for various noise types to classify target audio signals.

Wiener filtering of the COBE Differential Microwave Radiometer data

NASA Technical Reports Server (NTRS)

Bunn, Emory F.; Fisher, Karl B.; Hoffman, Yehuda; Lahav, Ofer; Silk, Joseph; Zaroubi, Saleem

1994-01-01

We derive an optimal linear filter to suppress the noise from the cosmic background explorer satellite (COBE) Differential Microwave Radiometer (DMR) sky maps for a given power spectrum. We then apply the filter to the first-year DMR data, after removing pixels within 20 deg of the Galactic plane from the data. We are able to identify particular hot and cold spots in the filtered maps at a level 2 to 3 times the noise level. We use the formalism of constrained realizations of Gaussian random fields to assess the uncertainty in the filtered sky maps. In addition to improving the signal-to-noise ratio of the map as a whole, these techniques allow us to recover some information about the cosmic microwave background anisotropy in the missing Galactic plane region. From these maps we are able to determine which hot and cold spots in the data are statistically significant, and which may have been produced by noise. In addition, the filtered maps can be used for comparison with other experiments on similar angular scales.

Complexity and multifractality of neuronal noise in mouse and human hippocampal epileptiform dynamics.

PubMed

Serletis, Demitre; Bardakjian, Berj L; Valiante, Taufik A; Carlen, Peter L

2012-10-01

Fractal methods offer an invaluable means of investigating turbulent nonlinearity in non-stationary biomedical recordings from the brain. Here, we investigate properties of complexity (i.e. the correlation dimension, maximum Lyapunov exponent, 1/f(γ) noise and approximate entropy) and multifractality in background neuronal noise-like activity underlying epileptiform transitions recorded at the intracellular and local network scales from two in vitro models: the whole-intact mouse hippocampus and lesional human hippocampal slices. Our results show evidence for reduced dynamical complexity and multifractal signal features following transition to the ictal epileptiform state. These findings suggest that pathological breakdown in multifractal complexity coincides with loss of signal variability or heterogeneity, consistent with an unhealthy ictal state that is far from the equilibrium of turbulent yet healthy fractal dynamics in the brain. Thus, it appears that background noise-like activity successfully captures complex and multifractal signal features that may, at least in part, be used to classify and identify brain state transitions in the healthy and epileptic brain, offering potential promise for therapeutic neuromodulatory strategies for afflicted patients suffering from epilepsy and other related neurological disorders.

Above the Noise: The Search for Periodicities in the Inner Heliosphere

NASA Astrophysics Data System (ADS)

Threlfall, James; De Moortel, Ineke; Conlon, Thomas

2017-11-01

Remote sensing of coronal and heliospheric periodicities can provide vital insight into the local conditions and dynamics of the solar atmosphere. We seek to trace long (one hour or longer) periodic oscillatory signatures (previously identified above the limb in the corona by, e.g., Telloni et al. in Astrophys. J. 767, 138, 2013) from their origin at the solar surface out into the heliosphere. To do this, we combined on-disk measurements taken by the Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO) and concurrent extreme ultra-violet (EUV) and coronagraph data from one of the Solar Terrestrial Relations Observatory (STEREO) spacecraft to study the evolution of two active regions in the vicinity of an equatorial coronal hole over several days in early 2011. Fourier and wavelet analysis of signals were performed. Applying white-noise-based confidence levels to the power spectra associated with detrended intensity time series yields detections of oscillatory signatures with periods from 6 - 13 hours in both AIA and STEREO data. As was found by Telloni et al. (2013), these signatures are aligned with local magnetic structures. However, typical spectral power densities all vary substantially as a function of period, indicating spectra dominated by red (rather than white) noise. Contrary to the white-noise-based results, applying global confidence levels based on a generic background-noise model (allowing a combination of white noise, red noise, and transients following Auchère et al. in Astrophys. J. 825, 110, 2016) without detrending the time series uncovers only sporadic, spatially uncorrelated evidence of periodic signatures in either instrument. Automating this method to individual pixels in the STEREO/COR coronagraph field of view is non-trivial. Efforts to identify and implement a more robust automatic background noise model fitting procedure are needed.

Edge enhancement and noise suppression for infrared image based on feature analysis

NASA Astrophysics Data System (ADS)

Jiang, Meng

2018-06-01

Infrared images are often suffering from background noise, blurred edges, few details and low signal-to-noise ratios. To improve infrared image quality, it is essential to suppress noise and enhance edges simultaneously. To realize it in this paper, we propose a novel algorithm based on feature analysis in shearlet domain. Firstly, as one of multi-scale geometric analysis (MGA), we introduce the theory and superiority of shearlet transform. Secondly, after analyzing the defects of traditional thresholding technique to suppress noise, we propose a novel feature extraction distinguishing image structures from noise well and use it to improve the traditional thresholding technique. Thirdly, with computing the correlations between neighboring shearlet coefficients, the feature attribute maps identifying the weak detail and strong edges are completed to improve the generalized unsharped masking (GUM). At last, experiment results with infrared images captured in different scenes demonstrate that the proposed algorithm suppresses noise efficiently and enhances image edges adaptively.

Preliminary measurement of the airframe noise from an F-106B delta wing aircraft at low flyover speeds. [establishment of lower limit for noise level of supersonic transport aircraft

NASA Technical Reports Server (NTRS)

Burley, R. R.

1974-01-01

To establish a realistic lower limit for the noise level of advanced supersonic transport aircraft will require knowledge concerning the amount of noise generated by the airframe itself as it moves through the air. The airframe noise level of an F-106B aircraft was determined and was compared to that predicted from an existing empirical relationship. The data were obtained from flyover and static tests conducted to determine the background noise level of the F-106B aircraft. Preliminary results indicate that the spectrum associated with airframe noise was broadband and peaked at a frequency of about 570 hertz. An existing empirical method successfully predicted the frequency where the spectrum peaked. However, the predicted OASPL value of 105 db was considerably greater than the measures value of 83 db.

Image quality enhancement in low-light-level ghost imaging using modified compressive sensing method

NASA Astrophysics Data System (ADS)

Shi, Xiaohui; Huang, Xianwei; Nan, Suqin; Li, Hengxing; Bai, Yanfeng; Fu, Xiquan

2018-04-01

Detector noise has a significantly negative impact on ghost imaging at low light levels, especially for existing recovery algorithm. Based on the characteristics of the additive detector noise, a method named modified compressive sensing ghost imaging is proposed to reduce the background imposed by the randomly distributed detector noise at signal path. Experimental results show that, with an appropriate choice of threshold value, modified compressive sensing ghost imaging algorithm can dramatically enhance the contrast-to-noise ratio of the object reconstruction significantly compared with traditional ghost imaging and compressive sensing ghost imaging methods. The relationship between the contrast-to-noise ratio of the reconstruction image and the intensity ratio (namely, the average signal intensity to average noise intensity ratio) for the three reconstruction algorithms are also discussed. This noise suppression imaging technique will have great applications in remote-sensing and security areas.

Low-frequency noise effect on terahertz tomography using thermal detectors.

PubMed

Guillet, J P; Recur, B; Balacey, H; Bou Sleiman, J; Darracq, F; Lewis, D; Mounaix, P

2015-08-01

In this paper, the impact of low-frequency noise on terahertz-computed tomography (THz-CT) is analyzed for several measurement configurations and pyroelectric detectors. We acquire real noise data from a continuous millimeter-wave tomographic scanner in order to figure out its impact on reconstructed images. Second, noise characteristics are quantified according to two distinct acquisition methods by (i) extrapolating from experimental acquisitions a sinogram for different noise backgrounds and (ii) reconstructing the corresponding spatial distributions in a slice using a CT reconstruction algorithm. Then we describe the low-frequency noise fingerprint and its influence on reconstructed images. Thanks to the observations, we demonstrate that some experimental choices can dramatically affect the 3D rendering of reconstructions. Thus, we propose some experimental methodologies optimizing the resulting quality and accuracy of the 3D reconstructions, with respect to the low-frequency noise characteristics observed during acquisitions.

Laboratory Study of the Noticeability and Annoyance of Sounds of Low Signal-to-Noise Ratio

NASA Technical Reports Server (NTRS)

Sneddon, Matthew; Howe, Richard; Pearsons, Karl; Fidell, Sanford

1996-01-01

This report describes a study of the noticeability and annoyance of intruding noises to test participants who were engaged in a distracting foreground task. Ten test participants read material of their own choosing while seated individually in front of a loudspeaker in an anechoic chamber. One of three specially constructed masking noise environments with limited dynamic range was heard at all times. A laboratory computer produced sounds of aircraft and ground vehicles as heard at varying distances at unpredictable intervals and carefully controlled levels. Test participants were instructed to click a computer mouse at any time that a noise distinct from the background noise environment came to their attention, and then to indicate their degree of annoyance with the noise that they had noticed. The results confirmed that both the noticeability of noise intrusions and their annoyance were closely related to their audibility.

Thermal background noise limitations

NASA Technical Reports Server (NTRS)

Gulkis, S.

1982-01-01

Modern detection systems are increasingly limited in sensitivity by the background thermal photons which enter the receiving system. Expressions for the fluctuations of detected thermal radiation are derived. Incoherent and heterodyne detection processes are considered. References to the subject of photon detection statistics are given.

Background noise spectra of global seismic stations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wada, M.M.; Claassen, J.P.

1996-08-01

Over an extended period of time station noise spectra were collected from various sources for use in estimating the detection and location performance of global networks of seismic stations. As the database of noise spectra enlarged and duplicate entries became available, an effort was mounted to more carefully select station noise spectra while discarding others. This report discusses the methodology and criteria by which the noise spectra were selected. It also identifies and illustrates the station noise spectra which survived the selection process and which currently contribute to the modeling efforts. The resulting catalog of noise statistics not only benefitsmore » those who model network performance but also those who wish to select stations on the basis of their noise level as may occur in designing networks or in selecting seismological data for analysis on the basis of station noise level. In view of the various ways by which station noise were estimated by the different contributors, it is advisable that future efforts which predict network performance have available station noise data and spectral estimation methods which are compatible with the statistics underlying seismic noise. This appropriately requires (1) averaging noise over seasonal and/or diurnal cycles, (2) averaging noise over time intervals comparable to those employed by actual detectors, and (3) using logarithmic measures of the noise.« less

Algorithm for astronomical, point source, signal to noise ratio calculations

NASA Technical Reports Server (NTRS)

Jayroe, R. R.; Schroeder, D. J.

1984-01-01

An algorithm was developed to simulate the expected signal to noise ratios as a function of observation time in the charge coupled device detector plane of an optical telescope located outside the Earth's atmosphere for a signal star, and an optional secondary star, embedded in a uniform cosmic background. By choosing the appropriate input values, the expected point source signal to noise ratio can be computed for the Hubble Space Telescope using the Wide Field/Planetary Camera science instrument.

Procedures for Estimating the Flat-Weighted Peak Level Produced by Surface and Buried Charges

DTIC Science & Technology

1988-08-01

Demolitions and Their Equivalent Weights 11 3 Blast Noise Complaint Potential 15 4 Results of Tests at Fort Lewis, WA in dB 16 5 Results of Tests at...PRODUCED BY SURFACE AND BURIED CHARGES 1 INTRODUCTION Background Blast noise from Army demolitions often causes residents of nearby communities to... blast noise were compared to measurements made at two different locations. The basic equations used in this procedure are discussed in detail in USA

An improved algorithm to reduce noise in high-order thermal ghost imaging.

PubMed

Chen, Xi-Hao; Wu, Shuang-Shuang; Wu, Wei; Guo, Wang-Yuan; Meng, Shao-Ying; Sun, Zhi-Bin; Zhai, Guang-Jie; Li, Ming-Fei; Wu, Ling-An

2014-09-01

A modified Nth-order correlation function is derived that can effectively remove the noise background encountered in high-order thermal light ghost imaging (GI). Based on this, the quality of the reconstructed images in an Nth-order lensless GI setup has been greatly enhanced compared to former high-order schemes for the same sampling number. In addition, the dependence of the visibility and signal-to-noise ratio for different high-order images on the sampling number has been measured and compared.

Brain Activation during Addition and Subtraction Tasks In-Noise and In-Quiet

PubMed Central

Abd Hamid, Aini Ismafairus; Yusoff, Ahmad Nazlim; Mukari, Siti Zamratol-Mai Sarah; Mohamad, Mazlyfarina

2011-01-01

Background: In spite of extensive research conducted to study how human brain works, little is known about a special function of the brain that stores and manipulates information—the working memory—and how noise influences this special ability. In this study, Functional magnetic resonance imaging (fMRI) was used to investigate brain responses to arithmetic problems solved in noisy and quiet backgrounds. Methods: Eighteen healthy young males performed simple arithmetic operations of addition and subtraction with in-quiet and in-noise backgrounds. The MATLAB-based Statistical Parametric Mapping (SPM8) was implemented on the fMRI datasets to generate and analyse the activated brain regions. Results: Group results showed that addition and subtraction operations evoked extended activation in the left inferior parietal lobe, left precentral gyrus, left superior parietal lobe, left supramarginal gyrus, and left middle temporal gyrus. This supported the hypothesis that the human brain relatively activates its left hemisphere more compared with the right hemisphere when solving arithmetic problems. The insula, middle cingulate cortex, and middle frontal gyrus, however, showed more extended right hemispheric activation, potentially due to the involvement of attention, executive processes, and working memory. For addition operations, there was extensive left hemispheric activation in the superior temporal gyrus, inferior frontal gyrus, and thalamus. In contrast, subtraction tasks evoked a greater activation of similar brain structures in the right hemisphere. For both addition and subtraction operations, the total number of activated voxels was higher for in-noise than in-quiet conditions. Conclusion: These findings suggest that when arithmetic operations were delivered auditorily, the auditory, attention, and working memory functions were required to accomplish the executive processing of the mathematical calculation. The respective brain activation patterns appear to be modulated by the noisy background condition. PMID:22135581

On the uncertainty in single molecule fluorescent lifetime and energy emission measurements

NASA Technical Reports Server (NTRS)

Brown, Emery N.; Zhang, Zhenhua; Mccollom, Alex D.

1995-01-01

Time-correlated single photon counting has recently been combined with mode-locked picosecond pulsed excitation to measure the fluorescent lifetimes and energy emissions of single molecules in a flow stream. Maximum likelihood (ML) and least square methods agree and are optimal when the number of detected photons is large however, in single molecule fluorescence experiments the number of detected photons can be less than 20, 67% of those can be noise and the detection time is restricted to 10 nanoseconds. Under the assumption that the photon signal and background noise are two independent inhomogeneous poisson processes, we derive the exact joint arrival time probably density of the photons collected in a single counting experiment performed in the presence of background noise. The model obviates the need to bin experimental data for analysis, and makes it possible to analyze formally the effect of background noise on the photon detection experiment using both ML or Bayesian methods. For both methods we derive the joint and marginal probability densities of the fluorescent lifetime and fluorescent emission. the ML and Bayesian methods are compared in an analysis of simulated single molecule fluorescence experiments of Rhodamine 110 using different combinations of expected background nose and expected fluorescence emission. While both the ML or Bayesian procedures perform well for analyzing fluorescence emissions, the Bayesian methods provide more realistic measures of uncertainty in the fluorescent lifetimes. The Bayesian methods would be especially useful for measuring uncertainty in fluorescent lifetime estimates in current single molecule flow stream experiments where the expected fluorescence emission is low. Both the ML and Bayesian algorithms can be automated for applications in molecular biology.

The Galker test of speech reception in noise; associations with background variables, middle ear status, hearing, and language in Danish preschool children.

PubMed

Lauritsen, Maj-Britt Glenn; Söderström, Margareta; Kreiner, Svend; Dørup, Jens; Lous, Jørgen

2016-01-01

We tested "the Galker test", a speech reception in noise test developed for primary care for Danish preschool children, to explore if the children's ability to hear and understand speech was associated with gender, age, middle ear status, and the level of background noise. The Galker test is a 35-item audio-visual, computerized word discrimination test in background noise. Included were 370 normally developed children attending day care center. The children were examined with the Galker test, tympanometry, audiometry, and the Reynell test of verbal comprehension. Parents and daycare teachers completed questionnaires on the children's ability to hear and understand speech. As most of the variables were not assessed using interval scales, non-parametric statistics (Goodman-Kruskal's gamma) were used for analyzing associations with the Galker test score. For comparisons, analysis of variance (ANOVA) was used. Interrelations were adjusted for using a non-parametric graphic model. In unadjusted analyses, the Galker test was associated with gender, age group, language development (Reynell revised scale), audiometry, and tympanometry. The Galker score was also associated with the parents' and day care teachers' reports on the children's vocabulary, sentence construction, and pronunciation. Type B tympanograms were associated with a mean hearing 5-6dB below that of than type A, C1, or C2. In the graphic analysis, Galker scores were closely and significantly related to Reynell test scores (Gamma (G)=0.35), the children's age group (G=0.33), and the day care teachers' assessment of the children's vocabulary (G=0.26). The Galker test of speech reception in noise appears promising as an easy and quick tool for evaluating preschool children's understanding of spoken words in noise, and it correlated well with the day care teachers' reports and less with the parents' reports. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Observer efficiency in free-localization tasks with correlated noise.

PubMed

Abbey, Craig K; Eckstein, Miguel P

2014-01-01

The efficiency of visual tasks involving localization has traditionally been evaluated using forced choice experiments that capitalize on independence across locations to simplify the performance of the ideal observer. However, developments in ideal observer analysis have shown how an ideal observer can be defined for free-localization tasks, where a target can appear anywhere in a defined search region and subjects respond by localizing the target. Since these tasks are representative of many real-world search tasks, it is of interest to evaluate the efficiency of observer performance in them. The central question of this work is whether humans are able to effectively use the information in a free-localization task relative to a similar task where target location is fixed. We use a yes-no detection task at a cued location as the reference for this comparison. Each of the tasks is evaluated using a Gaussian target profile embedded in four different Gaussian noise backgrounds having power-law noise power spectra with exponents ranging from 0 to 3. The free localization task had a square 6.7° search region. We report on two follow-up studies investigating efficiency in a detect-and-localize task, and the effect of processing the white-noise backgrounds. In the fixed-location detection task, we find average observer efficiency ranges from 35 to 59% for the different noise backgrounds. Observer efficiency improves dramatically in the tasks involving localization, ranging from 63 to 82% in the forced localization tasks and from 78 to 92% in the detect-and- localize tasks. Performance in white noise, the lowest efficiency condition, was improved by filtering to give them a power-law exponent of 2. Classification images, used to examine spatial frequency weights for the tasks, show better tuning to ideal weights in the free-localization tasks. The high absolute levels of efficiency suggest that observers are well-adapted to free-localization tasks.

Observer efficiency in free-localization tasks with correlated noise

PubMed Central

Abbey, Craig K.; Eckstein, Miguel P.

2014-01-01

The efficiency of visual tasks involving localization has traditionally been evaluated using forced choice experiments that capitalize on independence across locations to simplify the performance of the ideal observer. However, developments in ideal observer analysis have shown how an ideal observer can be defined for free-localization tasks, where a target can appear anywhere in a defined search region and subjects respond by localizing the target. Since these tasks are representative of many real-world search tasks, it is of interest to evaluate the efficiency of observer performance in them. The central question of this work is whether humans are able to effectively use the information in a free-localization task relative to a similar task where target location is fixed. We use a yes-no detection task at a cued location as the reference for this comparison. Each of the tasks is evaluated using a Gaussian target profile embedded in four different Gaussian noise backgrounds having power-law noise power spectra with exponents ranging from 0 to 3. The free localization task had a square 6.7° search region. We report on two follow-up studies investigating efficiency in a detect-and-localize task, and the effect of processing the white-noise backgrounds. In the fixed-location detection task, we find average observer efficiency ranges from 35 to 59% for the different noise backgrounds. Observer efficiency improves dramatically in the tasks involving localization, ranging from 63 to 82% in the forced localization tasks and from 78 to 92% in the detect-and- localize tasks. Performance in white noise, the lowest efficiency condition, was improved by filtering to give them a power-law exponent of 2. Classification images, used to examine spatial frequency weights for the tasks, show better tuning to ideal weights in the free-localization tasks. The high absolute levels of efficiency suggest that observers are well-adapted to free-localization tasks. PMID:24817854

Structural correlates of cognitive deficit and elevated gamma noise power in schizophrenia.

PubMed

Suazo, Vanessa; Díez, Álvaro; Montes, Carlos; Molina, Vicente

2014-03-01

The aim of this study was to assess the relation between cognition, gray matter (GM) volumes and gamma noise power (amount of background oscillatory activity in the gamma band) in schizophrenia. We explored the relation between cognitive performance and regional GM volumes using voxel-based morphometry (VBM), in order to discover if the association between gamma noise power (an electroencephalography measurement of background activity in the gamma band) and cognition is observed through structural deficits related to the disease. Noise power, magnetic resonance imaging and cognitive assessments were obtained in 17 drug-free paranoid patients with schizophrenia and 13 healthy controls. In comparison with controls, patients showed GM deficits at posterior cingulate (bilateral),left inferior parietal (supramarginal gyrus) and left inferior dorsolateral prefrontal regions. Patients exhibited a direct association between performance in working memory and right temporal (superior and inferior gyri) GM densities. They also displayed a negative association between right anterior cerebellum volume and gamma noise power at the frontal midline (Fz) site. A structural deficit in the cerebellum may be involved in gamma activity disorganization in schizophrenia. Temporal structural deficits may relate to cognitive dysfunction in this illness. © 2013 The Authors. Psychiatry and Clinical Neurosciences © 2013 Japanese Society of Psychiatry and Neurology.

Assessment of Noise and Associated Health Impacts at Selected Secondary Schools in Ibadan, Nigeria

PubMed Central

Ana, Godson R. E. E.; Shendell, Derek G.; Brown, G. E.; Sridhar, M. K. C.

2009-01-01

Background. Most schools in Ibadan, Nigeria, are located near major roads (mobile line sources). We conducted an initial assessment of noise levels and adverse noise-related health and learning effects. Methods. For this descriptive, cross-sectional study, four schools were selected randomly from eight participating in overall project. We administered 200 questionnaires, 50 per school, assessing health and learning-related outcomes. Noise levels (A-weighted decibels, dBA) were measured with calibrated sound level meters. Traffic density was assessed for school with the highest measured dBA. Observational checklists assessed noise control parameters and building physical attributes. Results. Short-term, cross-sectional school-day noise levels ranged 68.3–84.7 dBA. Over 60% of respondents reported that vehicular traffic was major source of noise, and over 70% complained being disturbed by noise. Three schools reported tiredness, and one school lack of concentration, as the most prevalent noise-related health problems. Conclusion. Secondary school occupants in Ibadan, Nigeria were potentially affected by exposure to noise from mobile line sources. PMID:20041025

Improving Efficiency in Multi-Strange Baryon Reconstruction in d-Au at STAR

NASA Astrophysics Data System (ADS)

Leight, William

2003-10-01

We report preliminary multi-strange baryon measurements for d-Au collisions recorded at RHIC by the STAR experiment. After using classical topological analysis, in which cuts for each discriminating variable are adjusted by hand, we investigate improvements in signal-to-noise optimization using Linear Discriminant Analysis (LDA). LDA is an algorithm for finding, in the n-dimensional space of the n discriminating variables, the axis on which the signal and noise distributions are most separated. LDA is the first step in moving towards more sophisticated techniques for signal-to-noise optimization, such as Artificial Neural Nets. Due to the relatively low background and sufficiently high yields of d-Au collisions, they form an ideal system to study these possibilities for improving reconstruction methods. Such improvements will be extremely important for forthcoming Au-Au runs in which the size of the combinatoric background is a major problem in reconstruction efforts.

Wavelet analysis techniques applied to removing varying spectroscopic background in calibration model for pear sugar content

NASA Astrophysics Data System (ADS)

Liu, Yande; Ying, Yibin; Lu, Huishan; Fu, Xiaping

2005-11-01

A new method is proposed to eliminate the varying background and noise simultaneously for multivariate calibration of Fourier transform near infrared (FT-NIR) spectral signals. An ideal spectrum signal prototype was constructed based on the FT-NIR spectrum of fruit sugar content measurement. The performances of wavelet based threshold de-noising approaches via different combinations of wavelet base functions were compared. Three families of wavelet base function (Daubechies, Symlets and Coiflets) were applied to estimate the performance of those wavelet bases and threshold selection rules by a series of experiments. The experimental results show that the best de-noising performance is reached via the combinations of Daubechies 4 or Symlet 4 wavelet base function. Based on the optimization parameter, wavelet regression models for sugar content of pear were also developed and result in a smaller prediction error than a traditional Partial Least Squares Regression (PLSR) mode.

Fringe-projection profilometry based on two-dimensional empirical mode decomposition.

PubMed

Zheng, Suzhen; Cao, Yiping

2013-11-01

In 3D shape measurement, because deformed fringes often contain low-frequency information degraded with random noise and background intensity information, a new fringe-projection profilometry is proposed based on 2D empirical mode decomposition (2D-EMD). The fringe pattern is first decomposed into numbers of intrinsic mode functions by 2D-EMD. Because the method has partial noise reduction, the background components can be removed to obtain the fundamental components needed to perform Hilbert transformation to retrieve the phase information. The 2D-EMD can effectively extract the modulation phase of a single direction fringe and an inclined fringe pattern because it is a full 2D analysis method and considers the relationship between adjacent lines of a fringe patterns. In addition, as the method does not add noise repeatedly, as does ensemble EMD, the data processing time is shortened. Computer simulations and experiments prove the feasibility of this method.

A novel star extraction method based on modified water flow model

NASA Astrophysics Data System (ADS)

Zhang, Hao; Niu, Yanxiong; Lu, Jiazhen; Ouyang, Zibiao; Yang, Yanqiang

2017-11-01

Star extraction is the essential procedure for attitude measurement of star sensor. The great challenge for star extraction is to segment star area exactly from various noise and background. In this paper, a novel star extraction method based on Modified Water Flow Model(MWFM) is proposed. The star image is regarded as a 3D terrain. The morphology is adopted for noise elimination and Tentative Star Area(TSA) selection. Star area can be extracted through adaptive water flowing within TSAs. This method can achieve accurate star extraction with improved efficiency under complex conditions such as loud noise and uneven backgrounds. Several groups of different types of star images are processed using proposed method. Comparisons with existing methods are conducted. Experimental results show that MWFM performs excellently under different imaging conditions. The star extraction rate is better than 95%. The star centroid accuracy is better than 0.075 pixels. The time-consumption is also significantly reduced.

Circuit Models and Experimental Noise Measurements of Micropipette Amplifiers for Extracellular Neural Recordings from Live Animals

PubMed Central

Chen, Chang Hao; Pun, Sio Hang; Mak, Peng Un; Vai, Mang I; Klug, Achim; Lei, Tim C.

2014-01-01

Glass micropipettes are widely used to record neural activity from single neurons or clusters of neurons extracellularly in live animals. However, to date, there has been no comprehensive study of noise in extracellular recordings with glass micropipettes. The purpose of this work was to assess various noise sources that affect extracellular recordings and to create model systems in which novel micropipette neural amplifier designs can be tested. An equivalent circuit of the glass micropipette and the noise model of this circuit, which accurately describe the various noise sources involved in extracellular recordings, have been developed. Measurement schemes using dead brain tissue as well as extracellular recordings from neurons in the inferior colliculus, an auditory brain nucleus of an anesthetized gerbil, were used to characterize noise performance and amplification efficacy of the proposed micropipette neural amplifier. According to our model, the major noise sources which influence the signal to noise ratio are the intrinsic noise of the neural amplifier and the thermal noise from distributed pipette resistance. These two types of noise were calculated and measured and were shown to be the dominating sources of background noise for in vivo experiments. PMID:25133158

Noise-immune multisensor transduction of speech

NASA Astrophysics Data System (ADS)

Viswanathan, Vishu R.; Henry, Claudia M.; Derr, Alan G.; Roucos, Salim; Schwartz, Richard M.

1986-08-01

Two types of configurations of multiple sensors were developed, tested and evaluated in speech recognition application for robust performance in high levels of acoustic background noise: One type combines the individual sensor signals to provide a single speech signal input, and the other provides several parallel inputs. For single-input systems, several configurations of multiple sensors were developed and tested. Results from formal speech intelligibility and quality tests in simulated fighter aircraft cockpit noise show that each of the two-sensor configurations tested outperforms the constituent individual sensors in high noise. Also presented are results comparing the performance of two-sensor configurations and individual sensors in speaker-dependent, isolated-word speech recognition tests performed using a commercial recognizer (Verbex 4000) in simulated fighter aircraft cockpit noise.

Photoswitching Near-Infrared Fluorescence from Polymer Nanoparticles Catapults Signals over the Region of Noises and Interferences for Enhanced Sensitivity.

PubMed

Wang, Jie; Lv, Yanlin; Wan, Wei; Wang, Xuefei; Li, Alexander D Q; Tian, Zhiyuan

2016-02-01

As a very sensitive technique, photoswitchable fluorescence not only gains ultrasensitivity but also imparts many novel and unexpected applications. Applications of near-infrared (NIR) fluorescence have demonstrated low background noises, high tissue-penetrating ability, and an ability to reduce photodamage to live cells. Because of these desired features, NIR-fluorescent dyes have been the premium among fluorescent dyes, and probes with photoswitchable NIR fluorescence are even more desirable for enhanced signal quality in the emerging optical imaging modalities but rarely used because they are extremely challenging to design and construct. Using a spiropyran derivative functioning as both a photoswitch and a fluorophore to launch its periodically modulated red fluorescence excitation energy into a NIR acceptor, we fabricated core-shell polymer nanoparticles exhibiting a photoswitchable fluorescence signal within the biological window (∼700-1000 nm) with a peak maximum of 776 nm. Live cells constantly synthesize new molecules, including fluorescent molecules, and also endocytose exogenous particles, including fluorescent particles. Upon excitation at different wavelengths, these fluorescent species bring about background noises and interferences covering nearly the whole visible region and therefore render many intracellular targets unaddressable. The oscillating NIR fluorescence signal with an on/off ratio of up to 67 that the polymer nanoparticles display is beyond the typical background noises and interferences, thus producing superior sharpness, reliability, and signal-to-noise ratios in cellular imaging. Taking these salient features, we anticipate that these types of nanoparticles will be useful for in vivo imaging of biological tissue and other complex specimens, where two-photon activation and excitation are used in combination with NIR-fluorescence photoswitching.

Informational Masking Effects on Neural Encoding of Stimulus Onset and Acoustic Change.

PubMed

Niemczak, Christopher E; Vander Werff, Kathy R

2018-05-18

Recent investigations using cortical auditory evoked potentials have shown masker-dependent effects on sensory cortical processing of speech information. Background noise maskers consisting of other people talking are particularly difficult for speech recognition. Behavioral studies have related this to perceptual masking, or informational masking, beyond just the overlap of the masker and target at the auditory periphery. The aim of the present study was to use cortical auditory evoked potentials, to examine how maskers (i.e., continuous speech-shaped noise [SSN] and multi-talker babble) affect the cortical sensory encoding of speech information at an obligatory level of processing. Specifically, cortical responses to vowel onset and formant change were recorded under different background noise conditions presumed to represent varying amounts of energetic or informational masking. The hypothesis was, that even at this obligatory cortical level of sensory processing, we would observe larger effects on the amplitude and latency of the onset and change components as the amount of informational masking increased across background noise conditions. Onset and change responses were recorded to a vowel change from /u-i/ in young adults under four conditions: quiet, continuous SSN, eight-talker (8T) babble, and two-talker (2T) babble. Repeated measures analyses by noise condition were conducted on amplitude, latency, and response area measurements to determine the differential effects of these noise conditions, designed to represent increasing and varying levels of informational and energetic masking, on cortical neural representation of a vowel onset and acoustic change response waveforms. All noise conditions significantly reduced onset N1 and P2 amplitudes, onset N1-P2 peak to peak amplitudes, as well as both onset and change response area compared with quiet conditions. Further, all amplitude and area measures were significantly reduced for the two babble conditions compared with continuous SSN. However, there were no significant differences in peak amplitude or area for either onset or change responses between the two different babble conditions (eight versus two talkers). Mean latencies for all onset peaks were delayed for noise conditions compared with quiet. However, in contrast to the amplitude and area results, differences in peak latency between SSN and the babble conditions did not reach statistical significance. These results support the idea that while background noise maskers generally reduce amplitude and increase latency of speech-sound evoked cortical responses, the type of masking has a significant influence. Speech babble maskers (eight talkers and two talkers) have a larger effect on the obligatory cortical response to speech sound onset and change compared with purely energetic continuous SSN maskers, which may be attributed to informational masking effects. Neither the neural responses to the onset nor the vowel change, however, were sensitive to the hypothesized increase in the amount of informational masking between speech babble maskers with two talkers compared with eight talkers.

Hilbert-Huang spectral analysis for characterizing the intrinsic time-scales of variability in decennial time-series of surface solar radiation

NASA Astrophysics Data System (ADS)

Bengulescu, Marc; Blanc, Philippe; Wald, Lucien

2016-04-01

An analysis of the variability of the surface solar irradiance (SSI) at different local time-scales is presented in this study. Since geophysical signals, such as long-term measurements of the SSI, are often produced by the non-linear interaction of deterministic physical processes that may also be under the influence of non-stationary external forcings, the Hilbert-Huang transform (HHT), an adaptive, noise-assisted, data-driven technique, is employed to extract locally - in time and in space - the embedded intrinsic scales at which a signal oscillates. The transform consists of two distinct steps. First, by means of the Empirical Mode Decomposition (EMD), the time-series is "de-constructed" into a finite number - often small - of zero-mean components that have distinct temporal scales of variability, termed hereinafter the Intrinsic Mode Functions (IMFs). The signal model of the components is an amplitude modulation - frequency modulation (AM - FM) one, and can also be thought of as an extension of a Fourier series having both time varying amplitude and frequency. Following the decomposition, Hilbert spectral analysis is then employed on the IMFs, yielding a time-frequency-energy representation that portrays changes in the spectral contents of the original data, with respect to time. As measurements of surface solar irradiance may possibly be contaminated by the manifestation of different type of stochastic processes (i.e. noise), the identification of real, physical processes from this background of random fluctuations is of interest. To this end, an adaptive background noise null hypothesis is assumed, based on the robust statistical properties of the EMD when applied to time-series of different classes of noise (e.g. white, red or fractional Gaussian). Since the algorithm acts as an efficient constant-Q dyadic, "wavelet-like", filter bank, the different noise inputs are decomposed into components having the same spectral shape, but that are translated to the next lower octave in the spectral domain. Thus, when the sampling step is increased, the spectral shape of IMFs cannot remain at its original position, due to the new lower Nyquist frequency, and is instead pushed toward the lower scaled frequency. Based on these features, the identification of potential signals within the data should become possible without any prior knowledge of the background noises. When applying the above outlined procedure to decennial time-series of surface solar irradiance, only the component that has an annual time-scale of variability is shown to have statistical properties that diverge from those of noise. Nevertheless, the noise-like components are not completely devoid of information, as it is found that their AM components have a non-null rank correlation coefficient with the annual mode, i.e. the background noise intensity seems to be modulated by the seasonal cycle. The findings have possible implications on the modelling and forecast of the surface solar irradiance, by discriminating its deterministic from its quasi-stochastic constituents, at distinct local time-scales.

Cascaded systems analysis of noise and detectability in dual-energy cone-beam CT

PubMed Central

Gang, Grace J.; Zbijewski, Wojciech; Webster Stayman, J.; Siewerdsen, Jeffrey H.

2012-01-01

Purpose: Dual-energy computed tomography and dual-energy cone-beam computed tomography (DE-CBCT) are promising modalities for applications ranging from vascular to breast, renal, hepatic, and musculoskeletal imaging. Accordingly, the optimization of imaging techniques for such applications would benefit significantly from a general theoretical description of image quality that properly incorporates factors of acquisition, reconstruction, and tissue decomposition in DE tomography. This work reports a cascaded systems analysis model that includes the Poisson statistics of x rays (quantum noise), detector model (flat-panel detectors), anatomical background, image reconstruction (filtered backprojection), DE decomposition (weighted subtraction), and simple observer models to yield a task-based framework for DE technique optimization. Methods: The theoretical framework extends previous modeling of DE projection radiography and CBCT. Signal and noise transfer characteristics are propagated through physical and mathematical stages of image formation and reconstruction. Dual-energy decomposition was modeled according to weighted subtraction of low- and high-energy images to yield the 3D DE noise-power spectrum (NPS) and noise-equivalent quanta (NEQ), which, in combination with observer models and the imaging task, yields the dual-energy detectability index (d′). Model calculations were validated with NPS and NEQ measurements from an experimental imaging bench simulating the geometry of a dedicated musculoskeletal extremities scanner. Imaging techniques, including kVp pair and dose allocation, were optimized using d′ as an objective function for three example imaging tasks: (1) kidney stone discrimination; (2) iodine vs bone in a uniform, soft-tissue background; and (3) soft tissue tumor detection on power-law anatomical background. Results: Theoretical calculations of DE NPS and NEQ demonstrated good agreement with experimental measurements over a broad range of imaging conditions. Optimization results suggest a lower fraction of total dose imparted by the low-energy acquisition, a finding consistent with previous literature. The selection of optimal kVp pair reveals the combined effect of both quantum noise and contrast in the kidney stone discrimination and soft-tissue tumor detection tasks, whereas the K-edge effect of iodine was the dominant factor in determining kVp pairs in the iodine vs bone task. The soft-tissue tumor task illustrated the benefit of dual-energy imaging in eliminating anatomical background noise and improving detectability beyond that achievable by single-energy scans. Conclusions: This work established a task-based theoretical framework that is predictive of DE image quality. The model can be utilized in optimizing a broad range of parameters in image acquisition, reconstruction, and decomposition, providing a useful tool for maximizing DE-CBCT image quality and reducing dose. PMID:22894440

Comparison of noise reduction systems

NASA Astrophysics Data System (ADS)

Noel, S. D.; Whitaker, R. W.

1991-06-01

When using infrasound as a tool for verification, the most important measurement to determine yield has been the peak-to-peak pressure amplitude of the signal. Therefore, there is a need to operate at the most favorable signal-to-noise ratio (SNR) possible. Winds near the ground can degrade the SNR, thereby making accurate signal amplitude measurement difficult. Wind noise reduction techniques were developed to help alleviate this problem; however, a noise reducing system should reduce the noise, and should not introduce distortion of coherent signals. An experiment is described to study system response for a variety of noise reducing configurations to a signal generated by an underground test (UGT) at the Nevada Test Site (NTS). In addition to the signal, background noise reduction is examined through measurements of variance. Sensors using two particular geometries of noise reducing equipment, the spider and the cross appear to deliver the best SNR. Because the spider configuration is easier to deploy, it is now the most commonly used.

Assessment of NASA's Aircraft Noise Prediction Capability

NASA Technical Reports Server (NTRS)

Dahl, Milo D. (Editor)

2012-01-01

A goal of NASA s Fundamental Aeronautics Program is the improvement of aircraft noise prediction. This document provides an assessment, conducted from 2006 to 2009, on the current state of the art for aircraft noise prediction by carefully analyzing the results from prediction tools and from the experimental databases to determine errors and uncertainties and compare results to validate the predictions. The error analysis is included for both the predictions and the experimental data and helps identify where improvements are required. This study is restricted to prediction methods and databases developed or sponsored by NASA, although in many cases they represent the current state of the art for industry. The present document begins with an introduction giving a general background for and a discussion on the process of this assessment followed by eight chapters covering topics at both the system and the component levels. The topic areas, each with multiple contributors, are aircraft system noise, engine system noise, airframe noise, fan noise, liner physics, duct acoustics, jet noise, and propulsion airframe aeroacoustics.

Detectability of auditory signals presented without defined observation intervals

NASA Technical Reports Server (NTRS)

Watson, C. S.; Nichols, T. L.

1976-01-01

Ability to detect tones in noise was measured without defined observation intervals. Latency density functions were estimated for the first response following a signal and, separately, for the first response following randomly distributed instances of background noise. Detection performance was measured by the maximum separation between the cumulative latency density functions for signal-plus-noise and for noise alone. Values of the index of detectability, estimated by this procedure, were approximately those obtained with a 2-dB weaker signal and defined observation intervals. Simulation of defined- and non-defined-interval tasks with an energy detector showed that this device performs very similarly to the human listener in both cases.

Characterization of transient noise in Advanced LIGO relevant to gravitational wave signal GW150914

NASA Astrophysics Data System (ADS)

Abbott, B. P.; Abbott, R.; Abbott, T. D.; Abernathy, M. R.; Acernese, F.; Ackley, K.; Adamo, M.; Adams, C.; Adams, T.; Addesso, P.; Adhikari, R. X.; Adya, V. B.; Affeldt, C.; Agathos, M.; Agatsuma, K.; Aggarwal, N.; Aguiar, O. D.; Aiello, L.; Ain, A.; Ajith, P.; Allen, B.; Allocca, A.; Altin, P. A.; Anderson, S. B.; Anderson, W. G.; Arai, K.; Araya, M. C.; Arceneaux, C. C.; Areeda, J. S.; Arnaud, N.; Arun, K. G.; Ascenzi, S.; Ashton, G.; Ast, M.; Aston, S. M.; Astone, P.; Aufmuth, P.; Aulbert, C.; Babak, S.; Bacon, P.; Bader, M. K. M.; Baker, P. T.; Baldaccini, F.; Ballardin, G.; Ballmer, S. W.; Barayoga, J. C.; Barclay, S. E.; Barish, B. C.; Barker, D.; Barone, F.; Barr, B.; Barsotti, L.; Barsuglia, M.; Barta, D.; Bartlett, J.; Bartos, I.; Bassiri, R.; Basti, A.; Batch, J. C.; Baune, C.; Bavigadda, V.; Bazzan, M.; Behnke, B.; Bejger, M.; Bell, A. S.; Bell, C. J.; Berger, B. K.; Bergman, J.; Bergmann, G.; Berry, C. P. L.; Bersanetti, D.; Bertolini, A.; Betzwieser, J.; Bhagwat, S.; Bhandare, R.; Bilenko, I. A.; Billingsley, G.; Birch, J.; Birney, R.; Biscans, S.; Bisht, A.; Bitossi, M.; Biwer, C.; Bizouard, M. A.; Blackburn, J. K.; Blackburn, L.; Blair, C. D.; Blair, D. G.; Blair, R. M.; Bloemen, S.; Bock, O.; Bodiya, T. P.; Boer, M.; Bogaert, G.; Bogan, C.; Bohe, A.; Bojtos, P.; Bond, C.; Bondu, F.; Bonnand, R.; Boom, B. A.; Bork, R.; Boschi, V.; Bose, S.; Bouffanais, Y.; Bozzi, A.; Bradaschia, C.; Brady, P. R.; Braginsky, V. B.; Branchesi, M.; Brau, J. E.; Briant, T.; Brillet, A.; Brinkmann, M.; Brisson, V.; Brockill, P.; Brooks, A. F.; Brown, D. A.; Brown, D. D.; Brown, N. M.; Buchanan, C. C.; Buikema, A.; Bulik, T.; Bulten, H. J.; Buonanno, A.; Buskulic, D.; Buy, C.; Byer, R. L.; Cadonati, L.; Cagnoli, G.; Cahillane, C.; Calderón Bustillo, J.; Callister, T.; Calloni, E.; Camp, J. B.; Cannon, K. C.; Cao, J.; Capano, C. D.; Capocasa, E.; Carbognani, F.; Caride, S.; Casanueva Diaz, J.; Casentini, C.; Caudill, S.; Cavaglià, M.; Cavalier, F.; Cavalieri, R.; Cella, G.; Cepeda, C. B.; Cerboni Baiardi, L.; Cerretani, G.; Cesarini, E.; Chakraborty, R.; Chalermsongsak, T.; Chamberlin, S. J.; Chan, M.; Chao, S.; Charlton, P.; Chassande-Mottin, E.; Chatterji, S.; Chen, H. Y.; Chen, Y.; Cheng, C.; Chincarini, A.; Chiummo, A.; Cho, H. S.; Cho, M.; Chow, J. H.; Christensen, N.; Chu, Q.; Chua, S.; Chung, S.; Ciani, G.; Clara, F.; Clark, J. A.; Cleva, F.; Coccia, E.; Cohadon, P.-F.; Colla, A.; Collette, C. G.; Cominsky, L.; Conte, A.; Conti, L.; Cook, D.; Corbitt, T. R.; Cornish, N.; Corsi, A.; Cortese, S.; Costa, C. A.; Coughlin, M. W.; Coughlin, S. B.; Coulon, J.-P.; Countryman, S. T.; Couvares, P.; Cowan, E. E.; Coward, D. M.; Cowart, M. J.; Coyne, D. C.; Coyne, R.; Craig, K.; Creighton, J. D. E.; Cripe, J.; Crowder, S. G.; Cumming, A.; Cunningham, L.; Cuoco, E.; Dal Canton, T.; Danilishin, S. L.; D'Antonio, S.; Danzmann, K.; Darman, N. S.; Dattilo, V.; Dave, I.; Daveloza, H. P.; Davier, M.; Davies, G. S.; Daw, E. J.; Day, R.; DeBra, D.; Debreczeni, G.; Degallaix, J.; De Laurentis, M.; Deléglise, S.; Del Pozzo, W.; Denker, T.; Dent, T.; Dereli, H.; Dergachev, V.; DeRosa, R. T.; De Rosa, R.; DeSalvo, R.; Dhurandhar, S.; Díaz, M. C.; Di Fiore, L.; Di Giovanni, M.; Di Lieto, A.; Di Pace, S.; Di Palma, I.; Di Virgilio, A.; Dojcinoski, G.; Dolique, V.; Donovan, F.; Dooley, K. L.; Doravari, S.; Douglas, R.; Downes, T. P.; Drago, M.; Drever, R. W. P.; Driggers, J. C.; Du, Z.; Ducrot, M.; Dwyer, S. E.; Edo, T. B.; Edwards, M. C.; Effler, A.; Eggenstein, H.-B.; Ehrens, P.; Eichholz, J.; Eikenberry, S. S.; Engels, W.; Essick, R. C.; Etzel, T.; Evans, M.; Evans, T. M.; Everett, R.; Factourovich, M.; Fafone, V.; Fair, H.; Fairhurst, S.; Fan, X.; Fang, Q.; Farinon, S.; Farr, B.; Farr, W. M.; Favata, M.; Fays, M.; Fehrmann, H.; Fejer, M. M.; Ferrante, I.; Ferreira, E. C.; Ferrini, F.; Fidecaro, F.; Fiori, I.; Fiorucci, D.; Fisher, R. P.; Flaminio, R.; Fletcher, M.; Fournier, J.-D.; Franco, S.; Frasca, S.; Frasconi, F.; Frei, Z.; Freise, A.; Frey, R.; Frey, V.; Fricke, T. T.; Fritschel, P.; Frolov, V. V.; Fulda, P.; Fyffe, M.; Gabbard, H. A. G.; Gair, J. R.; Gammaitoni, L.; Gaonkar, S. G.; Garufi, F.; Gatto, A.; Gaur, G.; Gehrels, N.; Gemme, G.; Gendre, B.; Genin, E.; Gennai, A.; George, J.; Gergely, L.; Germain, V.; Ghosh, Archisman; Ghosh, S.; Giaime, J. A.; Giardina, K. D.; Giazotto, A.; Gill, K.; Glaefke, A.; Goetz, E.; Goetz, R.; Gondan, L.; González, G.; Gonzalez Castro, J. M.; Gopakumar, A.; Gordon, N. A.; Gorodetsky, M. L.; Gossan, S. E.; Gosselin, M.; Gouaty, R.; Graef, C.; Graff, P. B.; Granata, M.; Grant, A.; Gras, S.; Gray, C.; Greco, G.; Green, A. C.; Groot, P.; Grote, H.; Grunewald, S.; Guidi, G. M.; Guo, X.; Gupta, A.; Gupta, M. K.; Gushwa, K. E.; Gustafson, E. K.; Gustafson, R.; Hacker, J. J.; Hall, B. R.; Hall, E. D.; Hammond, G.; Haney, M.; Hanke, M. M.; Hanks, J.; Hanna, C.; Hannam, M. D.; Hanson, J.; Hardwick, T.; Harms, J.; Harry, G. M.; Harry, I. W.; Hart, M. J.; Hartman, M. T.; Haster, C.-J.; Haughian, K.; Heidmann, A.; Heintze, M. C.; Heitmann, H.; Hello, P.; Hemming, G.; Hendry, M.; Heng, I. S.; Hennig, J.; Heptonstall, A. W.; Heurs, M.; Hild, S.; Hoak, D.; Hodge, K. A.; Hofman, D.; Hollitt, S. E.; Holt, K.; Holz, D. E.; Hopkins, P.; Hosken, D. J.; Hough, J.; Houston, E. A.; Howell, E. J.; Hu, Y. M.; Huang, S.; Huerta, E. A.; Huet, D.; Hughey, B.; Husa, S.; Huttner, S. H.; Huynh-Dinh, T.; Idrisy, A.; Indik, N.; Ingram, D. R.; Inta, R.; Isa, H. N.; Isac, J.-M.; Isi, M.; Islas, G.; Isogai, T.; Iyer, B. R.; Izumi, K.; Jacqmin, T.; Jang, H.; Jani, K.; Jaranowski, P.; Jawahar, S.; Jiménez-Forteza, F.; Johnson, W. W.; Jones, D. I.; Jones, R.; Jonker, R. J. G.; Ju, L.; K, Haris; Kalaghatgi, C. V.; Kalogera, V.; Kandhasamy, S.; Kang, G.; Kanner, J. B.; Karki, S.; Kasprzack, M.; Katsavounidis, E.; Katzman, W.; Kaufer, S.; Kaur, T.; Kawabe, K.; Kawazoe, F.; Kéfélian, F.; Kehl, M. S.; Keitel, D.; Kelley, D. B.; Kells, W.; Kennedy, R.; Key, J. S.; Khalaidovski, A.; Khalili, F. Y.; Khan, I.; Khan, S.; Khan, Z.; Khazanov, E. A.; Kijbunchoo, N.; Kim, C.; Kim, J.; Kim, K.; Kim, Nam-Gyu; Kim, Namjun; Kim, Y.-M.; King, E. J.; King, P. J.; Kinzel, D. L.; Kissel, J. S.; Kleybolte, L.; Klimenko, S.; Koehlenbeck, S. M.; Kokeyama, K.; Koley, S.; Kondrashov, V.; Kontos, A.; Korobko, M.; Korth, W. Z.; Kowalska, I.; Kozak, D. B.; Kringel, V.; Krishnan, B.; Królak, A.; Krueger, C.; Kuehn, G.; Kumar, P.; Kuo, L.; Kutynia, A.; Lackey, B. D.; Landry, M.; Lange, J.; Lantz, B.; Lasky, P. D.; Lazzarini, A.; Lazzaro, C.; Leaci, P.; Leavey, S.; Lebigot, E. O.; Lee, C. H.; Lee, H. K.; Lee, H. M.; Lee, K.; Lenon, A.; Leonardi, M.; Leong, J. R.; Leroy, N.; Letendre, N.; Levin, Y.; Levine, B. M.; Li, T. G. F.; Libson, A.; Littenberg, T. B.; Lockerbie, N. A.; Logue, J.; Lombardi, A. L.; Lord, J. E.; Lorenzini, M.; Loriette, V.; Lormand, M.; Losurdo, G.; Lough, J. D.; Lück, H.; Lundgren, A. P.; Luo, J.; Lynch, R.; Ma, Y.; MacDonald, T.; Machenschalk, B.; MacInnis, M.; Macleod, D. M.; Magaña-Sandoval, F.; Magee, R. M.; Mageswaran, M.; Majorana, E.; Maksimovic, I.; Malvezzi, V.; Man, N.; Mandel, I.; Mandic, V.; Mangano, V.; Mansell, G. L.; Manske, M.; Mantovani, M.; Marchesoni, F.; Marion, F.; Márka, S.; Márka, Z.; Markosyan, A. S.; Maros, E.; Martelli, F.; Martellini, L.; Martin, I. W.; Martin, R. M.; Martynov, D. V.; Marx, J. N.; Mason, K.; Masserot, A.; Massinger, T. J.; Masso-Reid, M.; Matichard, F.; Matone, L.; Mavalvala, N.; Mazumder, N.; Mazzolo, G.; McCarthy, R.; McClelland, D. E.; McCormick, S.; McGuire, S. C.; McIntyre, G.; McIver, J.; McManus, D. J.; McWilliams, S. T.; Meacher, D.; Meadors, G. D.; Meidam, J.; Melatos, A.; Mendell, G.; Mendoza-Gandara, D.; Mercer, R. A.; Merilh, E.; Merzougui, M.; Meshkov, S.; Messenger, C.; Messick, C.; Meyers, P. M.; Mezzani, F.; Miao, H.; Michel, C.; Middleton, H.; Mikhailov, E. E.; Milano, L.; Miller, J.; Millhouse, M.; Minenkov, Y.; Ming, J.; Mirshekari, S.; Mishra, C.; Mitra, S.; Mitrofanov, V. P.; Mitselmakher, G.; Mittleman, R.; Moggi, A.; Mohan, M.; Mohapatra, S. R. P.; Montani, M.; Moore, B. C.; Moore, C. J.; Moraru, D.; Moreno, G.; Morriss, S. R.; Mossavi, K.; Mours, B.; Mow-Lowry, C. M.; Mueller, C. L.; Mueller, G.; Muir, A. W.; Mukherjee, Arunava; Mukherjee, D.; Mukherjee, S.; Mukund, N.; Mullavey, A.; Munch, J.; Murphy, D. J.; Murray, P. G.; Mytidis, A.; Nardecchia, I.; Naticchioni, L.; Nayak, R. K.; Necula, V.; Nedkova, K.; Nelemans, G.; Neri, M.; Neunzert, A.; Newton, G.; Nguyen, T. T.; Nielsen, A. B.; Nissanke, S.; Nitz, A.; Nocera, F.; Nolting, D.; Normandin, M. E.; Nuttall, L. K.; Oberling, J.; Ochsner, E.; O'Dell, J.; Oelker, E.; Ogin, G. H.; Oh, J. J.; Oh, S. H.; Ohme, F.; Oliver, M.; Oppermann, P.; Oram, Richard J.; O'Reilly, B.; O'Shaughnessy, R.; Ottaway, D. J.; Ottens, R. S.; Overmier, H.; Owen, B. J.; Pai, A.; Pai, S. A.; Palamos, J. R.; Palashov, O.; Palomba, C.; Pal-Singh, A.; Pan, H.; Pankow, C.; Pannarale, F.; Pant, B. C.; Paoletti, F.; Paoli, A.; Papa, M. A.; Paris, H. R.; Parker, W.; Pascucci, D.; Pasqualetti, A.; Passaquieti, R.; Passuello, D.; Patricelli, B.; Patrick, Z.; Pearlstone, B. L.; Pedraza, M.; Pedurand, R.; Pekowsky, L.; Pele, A.; Penn, S.; Perreca, A.; Phelps, M.; Piccinni, O.; Pichot, M.; Piergiovanni, F.; Pierro, V.; Pillant, G.; Pinard, L.; Pinto, I. M.; Pitkin, M.; Poggiani, R.; Popolizio, P.; Post, A.; Powell, J.; Prasad, J.; Predoi, V.; Premachandra, S. S.; Prestegard, T.; Price, L. R.; Prijatelj, M.; Principe, M.; Privitera, S.; Prodi, G. A.; Prokhorov, L.; Puncken, O.; Punturo, M.; Puppo, P.; Pürrer, M.; Qi, H.; Qin, J.; Quetschke, V.; Quintero, E. A.; Quitzow-James, R.; Raab, F. J.; Rabeling, D. S.; Radkins, H.; Raffai, P.; Raja, S.; Rakhmanov, M.; Rapagnani, P.; Raymond, V.; Razzano, M.; Re, V.; Read, J.; Reed, C. M.; Regimbau, T.; Rei, L.; Reid, S.; Reitze, D. H.; Rew, H.; Reyes, S. D.; Ricci, F.; Riles, K.; Robertson, N. A.; Robie, R.; Robinet, F.; Rocchi, A.; Rolland, L.; Rollins, J. G.; Roma, V. J.; Romano, R.; Romanov, G.; Romie, J. H.; Rosińska, D.; Rowan, S.; Rüdiger, A.; Ruggi, P.; Ryan, K.; Sachdev, S.; Sadecki, T.; Sadeghian, L.; Salconi, L.; Saleem, M.; Salemi, F.; Samajdar, A.; Sammut, L.; Sanchez, E. J.; Sandberg, V.; Sandeen, B.; Sanders, J. R.; Sassolas, B.; Sathyaprakash, B. S.; Saulson, P. R.; Sauter, O.; Savage, R. L.; Sawadsky, A.; Schale, P.; Schilling, R.; Schmidt, J.; Schmidt, P.; Schnabel, R.; Schofield, R. M. S.; Schönbeck, A.; Schreiber, E.; Schuette, D.; Schutz, B. F.; Scott, J.; Scott, S. M.; Sellers, D.; Sengupta, A. S.; Sentenac, D.; Sequino, V.; Sergeev, A.; Serna, G.; Setyawati, Y.; Sevigny, A.; Shaddock, D. A.; Shah, S.; Shahriar, M. S.; Shaltev, M.; Shao, Z.; Shapiro, B.; Shawhan, P.; Sheperd, A.; Shoemaker, D. H.; Shoemaker, D. M.; Siellez, K.; Siemens, X.; Sigg, D.; Silva, A. D.; Simakov, D.; Singer, A.; Singer, L. P.; Singh, A.; Singh, R.; Singhal, A.; Sintes, A. M.; Slagmolen, B. J. J.; Slutsky, J.; Smith, J. R.; Smith, N. D.; Smith, R. J. E.; Son, E. J.; Sorazu, B.; Sorrentino, F.; Souradeep, T.; Srivastava, A. K.; Staley, A.; Steinke, M.; Steinlechner, J.; Steinlechner, S.; Steinmeyer, D.; Stephens, B. C.; Stone, R.; Strain, K. A.; Straniero, N.; Stratta, G.; Strauss, N. A.; Strigin, S.; Sturani, R.; Stuver, A. L.; Summerscales, T. Z.; Sun, L.; Sutton, P. J.; Swinkels, B. L.; Szczepańczyk, M. J.; Tacca, M.; Talukder, D.; Tanner, D. B.; Tápai, M.; Tarabrin, S. P.; Taracchini, A.; Taylor, R.; Theeg, T.; Thirugnanasambandam, M. P.; Thomas, E. G.; Thomas, M.; Thomas, P.; Thorne, K. A.; Thorne, K. S.; Thrane, E.; Tiwari, S.; Tiwari, V.; Tokmakov, K. V.; Tomlinson, C.; Tonelli, M.; Torres, C. V.; Torrie, C. I.; Töyrä, D.; Travasso, F.; Traylor, G.; Trifirò, D.; Tringali, M. C.; Trozzo, L.; Tse, M.; Turconi, M.; Tuyenbayev, D.; Ugolini, D.; Unnikrishnan, C. S.; Urban, A. L.; Usman, S. A.; Vahlbruch, H.; Vajente, G.; Valdes, G.; van Bakel, N.; van Beuzekom, M.; van den Brand, J. F. J.; Van Den Broeck, C.; Vander-Hyde, D. C.; van der Schaaf, L.; van Heijningen, J. V.; van Veggel, A. A.; Vardaro, M.; Vass, S.; Vasúth, M.; Vaulin, R.; Vecchio, A.; Vedovato, G.; Veitch, J.; Veitch, P. J.; Venkateswara, K.; Verkindt, D.; Vetrano, F.; Viceré, A.; Vinciguerra, S.; Vine, D. J.; Vinet, J.-Y.; Vitale, S.; Vo, T.; Vocca, H.; Vorvick, C.; Voss, D.; Vousden, W. D.; Vyatchanin, S. P.; Wade, A. R.; Wade, L. E.; Wade, M.; Walker, M.; Wallace, L.; Walsh, S.; Wang, G.; Wang, H.; Wang, M.; Wang, X.; Wang, Y.; Ward, R. L.; Warner, J.; Was, M.; Weaver, B.; Wei, L.-W.; Weinert, M.; Weinstein, A. J.; Weiss, R.; Welborn, T.; Wen, L.; Weßels, P.; Westphal, T.; Wette, K.; Whelan, J. T.; Whitcomb, S.; White, D. J.; Whiting, B. F.; Williams, R. D.; Williamson, A. R.; Willis, J. L.; Willke, B.; Wimmer, M. H.; Winkler, W.; Wipf, C. C.; Wittel, H.; Woan, G.; Worden, J.; Wright, J. L.; Wu, G.; Yablon, J.; Yam, W.; Yamamoto, H.; Yancey, C. C.; Yap, M. J.; Yu, H.; Yvert, M.; Zadrożny, A.; Zangrando, L.; Zanolin, M.; Zendri, J.-P.; Zevin, M.; Zhang, F.; Zhang, L.; Zhang, M.; Zhang, Y.; Zhao, C.; Zhou, M.; Zhou, Z.; Zhu, X. J.; Zotov, N.; Zucker, M. E.; Zuraw, S. E.; Zweizig, J.; LIGO Scientific Collaboration; Virgo Collaboration

2016-07-01

On 14 September 2015, a gravitational wave signal from a coalescing black hole binary system was observed by the Advanced LIGO detectors. This paper describes the transient noise backgrounds used to determine the significance of the event (designated GW150914) and presents the results of investigations into potential correlated or uncorrelated sources of transient noise in the detectors around the time of the event. The detectors were operating nominally at the time of GW150914. We have ruled out environmental influences and non-Gaussian instrument noise at either LIGO detector as the cause of the observed gravitational wave signal.

Characterization of Transient Noise in Advanced LIGO Relevant to Gravitational Wave Signal GW150914

NASA Technical Reports Server (NTRS)

Abbott, B. P.; Abbott, R.; Abbott, T. D.; Abernathy, M. R.; Acernese, F.; Ackley, K.; Adamo, M.; Adams, C.; Adams, T.; Camp, Jordan B.

2016-01-01

On 14 September 2015, a gravitational wave signal from a coalescing black hole binary system was observed by the Advanced LIGO detectors. This paper describes the transient noise backgrounds used to determine the significance of the event (designated GW150914) and presents the results of investigations into potential correlated or uncorrelated sources of transient noise in the detectors around the time of the event. The detectors were operating nominally at the time of GW150914. We have ruled out environmental influences and non-Gaussian instrument noise at either LIGO detector as the cause of the observed gravitational wave signal.

Selected methods for quantification of community exposure to aircraft noise

NASA Technical Reports Server (NTRS)

Edge, P. M., Jr.; Cawthorn, J. M.

1976-01-01

A review of the state-of-the-art for the quantification of community exposure to aircraft noise is presented. Physical aspects, people response considerations, and practicalities of useful application of scales of measure are included. Historical background up through the current technology is briefly presented. The developments of both single-event and multiple-event scales are covered. Selective choice is made of scales currently in the forefront of interest and recommended methodology is presented for use in computer programing to translate aircraft noise data into predictions of community noise exposure. Brief consideration is given to future programing developments and to supportive research needs.

The gap-prepulse inhibition deficit of the cortical N1-P2 complex in patients with tinnitus: The effect of gap duration.

PubMed

Ku, Yunseo; Ahn, Joong Woo; Kwon, Chiheon; Kim, Do Youn; Suh, Myung-Whan; Park, Moo Kyun; Lee, Jun Ho; Oh, Seung Ha; Kim, Hee Chan

2017-05-01

The present study aimed to investigate whether gap-prepulse inhibition (GPI) deficit in patients with tinnitus occurred in the N1-P2 complex of the cortical auditory evoked potential. Auditory late responses to the intense sound of the GPI paradigm were obtained from 16 patients with tinnitus and 18 age- and hearing loss-matched controls without tinnitus. The inhibition degrees of the N1-P2 complex were assessed at 100-, 50-, and 20-ms gap durations with tinnitus-pitch-matched and non-matched frequency background noises. At the 20-ms gap condition with the tinnitus-pitch-matched frequency background noise, only the tinnitus group showed an inhibition deficit of the N1-P2 complex. The inhibition deficits were absent in both groups with longer gap durations. These findings suggested that the effect of tinnitus emerged depending on the cue onset timing and duration of the gap-prepulse. Since inhibition deficits were observed in both groups at the same 20-ms gap condition, but with the tinnitus-pitch-non-matched frequency background noise, the present study did not offer proof of concept for tinnitus filling in the gap. Additional studies on the intrinsic effects of different background frequencies on the gap processing are required in the future. Copyright © 2017 Elsevier B.V. All rights reserved.

Effects of Noise and Proficiency on Intelligibility of Chinese-Accented English

ERIC Educational Resources Information Center

Rogers, Catherine L.; Dalby, Jonathan; Nishi, Kanae

2004-01-01

This study compared the intelligibility of native and foreign-accented English speech presented in quiet and mixed with three different levels of background noise. Two native American English speakers and four native Mandarin Chinese speakers for whom English is a second language each read a list of 50 phonetically balanced sentences (Egan, 1948).…

Word Learning in Clear and Plain Speech in Quiet and Noisy Listening Conditions

ERIC Educational Resources Information Center

Riley, Kristine Marie Grohne

2010-01-01

Previous research demonstrates enhanced speech perception abilities for typically hearing and hearing-impaired listeners when speakers use clear versus plain speech, particularly in the presence of background noise. To date, very few studies have investigated the effects of noise on word learning and no studies have examined the effects of clear…

Graphical Man/Machine Communications

DTIC Science & Technology

1972-12-01

several others. The principal accomplishments are the development of a homomorphic imane deblurring method by E. Randolph Cole, the research into human...visual modelling by Patrick Baudelair, the impressive demonstrations of background noise elimination by Neil J. Miller, and the innovation of...characteristics for the homomorphical ly estimated restoration filter in the presence of additive noise were derived, and they show that the

Cortical activity patterns predict robust speech discrimination ability in noise

PubMed Central

Shetake, Jai A.; Wolf, Jordan T.; Cheung, Ryan J.; Engineer, Crystal T.; Ram, Satyananda K.; Kilgard, Michael P.

2012-01-01

The neural mechanisms that support speech discrimination in noisy conditions are poorly understood. In quiet conditions, spike timing information appears to be used in the discrimination of speech sounds. In this study, we evaluated the hypothesis that spike timing is also used to distinguish between speech sounds in noisy conditions that significantly degrade neural responses to speech sounds. We tested speech sound discrimination in rats and recorded primary auditory cortex (A1) responses to speech sounds in background noise of different intensities and spectral compositions. Our behavioral results indicate that rats, like humans, are able to accurately discriminate consonant sounds even in the presence of background noise that is as loud as the speech signal. Our neural recordings confirm that speech sounds evoke degraded but detectable responses in noise. Finally, we developed a novel neural classifier that mimics behavioral discrimination. The classifier discriminates between speech sounds by comparing the A1 spatiotemporal activity patterns evoked on single trials with the average spatiotemporal patterns evoked by known sounds. Unlike classifiers in most previous studies, this classifier is not provided with the stimulus onset time. Neural activity analyzed with the use of relative spike timing was well correlated with behavioral speech discrimination in quiet and in noise. Spike timing information integrated over longer intervals was required to accurately predict rat behavioral speech discrimination in noisy conditions. The similarity of neural and behavioral discrimination of speech in noise suggests that humans and rats may employ similar brain mechanisms to solve this problem. PMID:22098331

Single sources in the low-frequency gravitational wave sky: properties and time to detection by pulsar timing arrays

NASA Astrophysics Data System (ADS)

Kelley, Luke Zoltan; Blecha, Laura; Hernquist, Lars; Sesana, Alberto; Taylor, Stephen R.

2018-06-01

We calculate the properties, occurrence rates and detection prospects of individually resolvable `single sources' in the low-frequency gravitational wave (GW) spectrum. Our simulations use the population of galaxies and massive black hole binaries from the Illustris cosmological hydrodynamic simulations, coupled to comprehensive semi-analytic models of the binary merger process. Using mock pulsar timing arrays (PTA) with, for the first time, varying red-noise models, we calculate plausible detection prospects for GW single sources and the stochastic GW background (GWB). Contrary to previous results, we find that single sources are at least as detectable as the GW background. Using mock PTA, we find that these `foreground' sources (also `deterministic'/`continuous') are likely to be detected with ˜20 yr total observing baselines. Detection prospects, and indeed the overall properties of single sources, are only moderately sensitive to binary evolution parameters - namely eccentricity and environmental coupling, which can lead to differences of ˜5 yr in times to detection. Red noise has a stronger effect, roughly doubling the time to detection of the foreground between a white-noise only model (˜10-15 yr) and severe red noise (˜20-30 yr). The effect of red noise on the GWB is even stronger, suggesting that single source detections may be more robust. We find that typical signal-to-noise ratios for the foreground peak near f = 0.1 yr-1, and are much less sensitive to the continued addition of new pulsars to PTA.

Evidence of degraded representation of speech in noise, in the aging midbrain and cortex

PubMed Central

Simon, Jonathan Z.; Anderson, Samira

2016-01-01

Humans have a remarkable ability to track and understand speech in unfavorable conditions, such as in background noise, but speech understanding in noise does deteriorate with age. Results from several studies have shown that in younger adults, low-frequency auditory cortical activity reliably synchronizes to the speech envelope, even when the background noise is considerably louder than the speech signal. However, cortical speech processing may be limited by age-related decreases in the precision of neural synchronization in the midbrain. To understand better the neural mechanisms contributing to impaired speech perception in older adults, we investigated how aging affects midbrain and cortical encoding of speech when presented in quiet and in the presence of a single-competing talker. Our results suggest that central auditory temporal processing deficits in older adults manifest in both the midbrain and in the cortex. Specifically, midbrain frequency following responses to a speech syllable are more degraded in noise in older adults than in younger adults. This suggests a failure of the midbrain auditory mechanisms needed to compensate for the presence of a competing talker. Similarly, in cortical responses, older adults show larger reductions than younger adults in their ability to encode the speech envelope when a competing talker is added. Interestingly, older adults showed an exaggerated cortical representation of speech in both quiet and noise conditions, suggesting a possible imbalance between inhibitory and excitatory processes, or diminished network connectivity that may impair their ability to encode speech efficiently. PMID:27535374

Error reduction study employing a pseudo-random binary sequence for use in acoustic pyrometry of gases

NASA Astrophysics Data System (ADS)

Ewan, B. C. R.; Ireland, S. N.

2000-12-01

Acoustic pyrometry uses the temperature dependence of sound speed in materials to measure temperature. This is normally achieved by measuring the transit time for a sound signal over a known path length and applying the material relation between temperature and velocity to extract an "average" temperature. Sources of error associated with the measurement of mean transit time are discussed in implementing the technique in gases, one of the principal causes being background noise in typical industrial environments. A number of transmitted signal and processing strategies which can be used in the area are examined and the expected error in mean transit time associated with each technique is quantified. Transmitted signals included pulses, pure frequencies, chirps, and pseudorandom binary sequences (prbs), while processing involves edge detection and correlation. Errors arise through the misinterpretation of the positions of edge arrival or correlation peaks due to instantaneous deviations associated with background noise and these become more severe as signal to noise amplitude ratios decrease. Population errors in the mean transit time are estimated for the different measurement strategies and it is concluded that PRBS combined with correlation can provide the lowest errors when operating in high noise environments. The operation of an instrument based on PRBS transmitted signals is described and test results under controlled noise conditions are presented. These confirm the value of the strategy and demonstrate that measurements can be made with signal to noise amplitude ratios down to 0.5.

Acoustical evaluation of preschool classrooms

NASA Astrophysics Data System (ADS)

Yang, Wonyoung; Hodgson, Murray

2003-10-01

An investigation was made of the acoustical environments in the Berwick Preschool, Vancouver, in response to complaints by the teachers. Reverberation times (RT), background noise levels (BNL), and in-class sound levels (Leq) were measured for acoustical evaluation in the classrooms. With respect to the measured RT and BNL, none of the classrooms in the preschool were acceptable according to the criteria relevant to this study. A questionnaire was administered to the teachers to assess their subjective responses to the acoustical and nonacoustical environments of the classrooms. Teachers agreed that the nonacoustical environments in the classrooms were fair, but that the acoustical environments had problems. Eight different classroom configurations were simulated to improve the acoustical environments, using the CATT room acoustical simulation program. When the surface absorption was increased, both the RT and speech levels decreased. RASTI was dependent on the volumes of the classrooms when the background noise levels were high; however, it depended on the total absorption of the classrooms when the background noise levels were low. Ceiling heights are critical as well. It is recommended that decreasing the volume of the classrooms is effective. Sound absorptive materials should be added to the walls or ceiling.

Exploring Seismic Noise with the USArray Transportable Array

NASA Astrophysics Data System (ADS)

Woodward, R.; Busby, R. W.; Simpson, D. W.

2009-12-01

The large number of seismic stations that comprise the EarthScope USArray Transportable Array (TA) seismic network provide an unparalleled opportunity for studying how seismic noise evolves with time over a large portion of the North American continent. Power spectra for every station in the TA data are computed automatically, for every hour of every station-day, by the Quality Analysis Control Kit (QUACK) system at the IRIS Data Management Center. The power spectra utilize hour-long data segments, with 50% overlap between segments, providing spectral values in the band between 20 Hz and 172 s. Thus, at any in-band frequency one can construct a continuous two-year time history of seismic noise for every TA station. When the time variation of the power spectra values across the array are rendered as individual movie frames one can examine the evolution of seismic noise across the full spatio-temporal extent of the TA. Overall, the background noise levels (especially at periods below 10 s) are remarkably uniform across the entire array. Numerous expected features are present, including diurnal and annual variations, enhanced noise levels at coastal stations, transients related to large storms, and episodes when the observations of background noise are dominated by earthquake energy. Upgrades to the TA station instrumentation will provide the capability to measure additional physical factors relevant to seismic noise. All TA stations deployed after August 2009 include MEMS barometers that can measure atmospheric pressure from DC to approximately 0.1 Hz. In additional, several stations have been temporarily equipped with infrasound sensors. Previous research has highlighted the direct effect of atmospheric pressure fluctuations on very long period vertical seismometers. The relationship to noise observed on horizontal seismometers is more complex. However, with a large number of uniform installations it may be possible to make further progress. We will present analyses of the spatio-temporal evolution of noise observed on the TA stations and present preliminary results from the barometers and infrasound sensors that have been deployed with TA stations so far. We will discuss opportunities for augmenting TA stations with additional sensors that may further elucidate seismic noise processes.

Lateralization of music processing with noises in the auditory cortex: an fNIRS study.

PubMed

Santosa, Hendrik; Hong, Melissa Jiyoun; Hong, Keum-Shik

2014-01-01

The present study is to determine the effects of background noise on the hemispheric lateralization in music processing by exposing 14 subjects to four different auditory environments: music segments only, noise segments only, music + noise segments, and the entire music interfered by noise segments. The hemodynamic responses in both hemispheres caused by the perception of music in 10 different conditions were measured using functional near-infrared spectroscopy. As a feature to distinguish stimulus-evoked hemodynamics, the difference between the mean and the minimum value of the hemodynamic response for a given stimulus was used. The right-hemispheric lateralization in music processing was about 75% (instead of continuous music, only music segments were heard). If the stimuli were only noises, the lateralization was about 65%. But, if the music was mixed with noises, the right-hemispheric lateralization has increased. Particularly, if the noise was a little bit lower than the music (i.e., music level 10~15%, noise level 10%), the entire subjects showed the right-hemispheric lateralization: This is due to the subjects' effort to hear the music in the presence of noises. However, too much noise has reduced the subjects' discerning efforts.

Lateralization of music processing with noises in the auditory cortex: an fNIRS study

PubMed Central

Santosa, Hendrik; Hong, Melissa Jiyoun; Hong, Keum-Shik

2014-01-01

The present study is to determine the effects of background noise on the hemispheric lateralization in music processing by exposing 14 subjects to four different auditory environments: music segments only, noise segments only, music + noise segments, and the entire music interfered by noise segments. The hemodynamic responses in both hemispheres caused by the perception of music in 10 different conditions were measured using functional near-infrared spectroscopy. As a feature to distinguish stimulus-evoked hemodynamics, the difference between the mean and the minimum value of the hemodynamic response for a given stimulus was used. The right-hemispheric lateralization in music processing was about 75% (instead of continuous music, only music segments were heard). If the stimuli were only noises, the lateralization was about 65%. But, if the music was mixed with noises, the right-hemispheric lateralization has increased. Particularly, if the noise was a little bit lower than the music (i.e., music level 10~15%, noise level 10%), the entire subjects showed the right-hemispheric lateralization: This is due to the subjects' effort to hear the music in the presence of noises. However, too much noise has reduced the subjects' discerning efforts. PMID:25538583

Modelling a C-Band Space Surveillance Radar using Systems Tool Kit

DTIC Science & Technology

2013-02-01

directly) or ‘Calculate’ by selecting to use: Earth, Sun, Atmosphere, Rain, Clouds & Fog, Tropo Scintillation, and/or Cosmic Background noise in the...OVERVIEW OF THE RADAR.......................................................................................... 2 2.1 Background ...performance described in previous work [1]. UNCLASSIFIED 1 UNCLASSIFIED DSTO-TN-1164 2. Overview of the Radar 2.1 Background The AN/FPQ-14 is a

Why background colour matters to bees and flowers.

PubMed

Bukovac, Zoë; Shrestha, Mani; Garcia, Jair E; Burd, Martin; Dorin, Alan; Dyer, Adrian G

2017-05-01

Flowers are often viewed by bee pollinators against a variety of different backgrounds. On the Australian continent, backgrounds are very diverse and include surface examples of all major geological stages of the Earth's history, which have been present during the entire evolutionary period of Angiosperms. Flower signals in Australia are also representative of typical worldwide evolutionary spectral adaptations that enable successful pollination. We measured the spectral properties of 581 natural surfaces, including rocks, sand, green leaves, and dry plant materials, sampled from tropical Cairns through to the southern tip of mainland Australia. We modelled in a hexagon colour space, how interactions between background spectra and flower-like colour stimuli affect reliable discrimination and detection in bee pollinators. We calculated the extent to which a given locus would be conflated with the loci of a different flower-colour stimulus using empirically determined colour discrimination regions for bee vision. Our results reveal that whilst colour signals are robust in homogeneous background viewing conditions, there could be significant pressure on plant flowers to evolve saliently-different colours to overcome background spectral noise. We thus show that perceptual noise has a large influence on how colour information can be used in natural conditions.

Topology of microwave background fluctuations - Theory

NASA Technical Reports Server (NTRS)

Gott, J. Richard, III; Park, Changbom; Bies, William E.; Bennett, David P.; Juszkiewicz, Roman

1990-01-01

Topological measures are used to characterize the microwave background temperature fluctuations produced by 'standard' scenarios (Gaussian) and by cosmic strings (non-Gaussian). Three topological quantities: total area of the excursion regions, total length, and total curvature (genus) of the isotemperature contours, are studied for simulated Gaussian microwave background anisotropy maps and then compared with those of the non-Gaussian anisotropy pattern produced by cosmic strings. In general, the temperature gradient field shows the non-Gaussian behavior of the string map more distinctively than the temperature field for all topology measures. The total contour length and the genus are found to be more sensitive to the existence of a stringy pattern than the usual temperature histogram. Situations when instrumental noise is superposed on the map, are considered to find the critical signal-to-noise ratio for which strings can be detected.

Brainstem transcription of speech is disrupted in children with autism spectrum disorders

PubMed Central

Russo, Nicole; Nicol, Trent; Trommer, Barbara; Zecker, Steve; Kraus, Nina

2009-01-01

Language impairment is a hallmark of autism spectrum disorders (ASD). The origin of the deficit is poorly understood although deficiencies in auditory processing have been detected in both perception and cortical encoding of speech sounds. Little is known about the processing and transcription of speech sounds at earlier (brainstem) levels or about how background noise may impact this transcription process. Unlike cortical encoding of sounds, brainstem representation preserves stimulus features with a degree of fidelity that enables a direct link between acoustic components of the speech syllable (e.g., onsets) to specific aspects of neural encoding (e.g., waves V and A). We measured brainstem responses to the syllable /da/, in quiet and background noise, in children with and without ASD. Children with ASD exhibited deficits in both the neural synchrony (timing) and phase locking (frequency encoding) of speech sounds, despite normal click-evoked brainstem responses. They also exhibited reduced magnitude and fidelity of speech-evoked responses and inordinate degradation of responses by background noise in comparison to typically developing controls. Neural synchrony in noise was significantly related to measures of core and receptive language ability. These data support the idea that abnormalities in the brainstem processing of speech contribute to the language impairment in ASD. Because it is both passively-elicited and malleable, the speech-evoked brainstem response may serve as a clinical tool to assess auditory processing as well as the effects of auditory training in the ASD population. PMID:19635083

Adaptive Noise Suppression of Pediatric Lung Auscultations With Real Applications to Noisy Clinical Settings in Developing Countries

PubMed Central

Emmanouilidou, Dimitra; McCollum, Eric D.; Park, Daniel E.

2015-01-01

Goal Chest auscultation constitutes a portable low-cost tool widely used for respiratory disease detection. Though it offers a powerful means of pulmonary examination, it remains riddled with a number of issues that limit its diagnostic capability. Particularly, patient agitation (especially in children), background chatter, and other environmental noises often contaminate the auscultation, hence affecting the clarity of the lung sound itself. This paper proposes an automated multiband denoising scheme for improving the quality of auscultation signals against heavy background contaminations. Methods The algorithm works on a simple two-microphone setup, dynamically adapts to the background noise and suppresses contaminations while successfully preserving the lung sound content. The proposed scheme is refined to offset maximal noise suppression against maintaining the integrity of the lung signal, particularly its unknown adventitious components that provide the most informative diagnostic value during lung pathology. Results The algorithm is applied to digital recordings obtained in the field in a busy clinic in West Africa and evaluated using objective signal fidelity measures and perceptual listening tests performed by a panel of licensed physicians. A strong preference of the enhanced sounds is revealed. Significance The strengths and benefits of the proposed method lie in the simple automated setup and its adaptive nature, both fundamental conditions for everyday clinical applicability. It can be simply extended to a real-time implementation, and integrated with lung sound acquisition protocols. PMID:25879837

Optimization of visual evoked potential (VEP) recording systems.

PubMed

Karanjia, Rustum; Brunet, Donald G; ten Hove, Martin W

2009-01-01

To explore the influence of environmental conditions on pattern visual evoked potential (VEP) recordings. Fourteen subjects with no known ocular pathology were recruited for the study. In an attempt to optimize the recording conditions, VEP recordings were performed in both the seated and recumbent positions. Comparisons were made between recordings using either LCD or CRT displays and recordings obtained in silence or with quiet background music. Paired recordings (in which only one variable was changed) were analyzed for changes in P100 latency, RMS noise, and variability. Baseline RMS noise demonstrated a significant decrease in the variability during the first 50msec accompanied by a 73% decrease in recording time for recumbent position when compared to the seated position (p<0.05). Visual evoked potentials recorded using LCD monitors demonstrated a significant increase in the P100 latency when compared to CRT recordings in the same subjects. The addition of background music did not affect the amount of RMS noise during the first 50msec of the recordings. This study demonstrates that the use of the recumbent position increases patient comfort and improves the signal to noise ratio. In contrast, the addition of background music to relax the patient did not improve the recording signal. Furthermore, the study illustrates the importance of avoiding low-contrast visual stimulation patterns obtained with LCD as they lead to higher latencies resulting in false positive recordings. These findings are important when establishing or modifying a pattern VEP recording protocol.

Reception thresholds for sentences in quiet, continuous noise, and interrupted noise in school-age children.

PubMed

Stuart, Andrew

2008-02-01

Sentence recognition in noise was employed to investigate the development of temporal resolution in school-age children. Eighty children aged 6 to 15 years and 16 young adults participated. Reception thresholds for sentences (RTSs) were determined in quiet and in backgrounds of competing continuous and interrupted noise. In the noise conditions, RTSs were determined with a fixed noise level. RTSs were higher in quiet for six- to seven-year-old children (p = .006). Performance was better in the interrupted noise evidenced by lower RTS signal-to-noise ratios (S/Ns) relative to continuous noise (p < .0001). An effect of age was found in noise (p < .0001) where RTS S/Ns decreased with increasing age. Specifically, children under 14 years performed worse than adults. "Release from masking" was computed by subtracting RTS S/Ns in interrupted noise from continuous noise for each participant. There was no significant difference in RTS S/N difference scores as a function of age (p = .057). Children were more adversely affected by noise and needed greater S/Ns in order to perform as well as adults. Since there was no effect of age on the amount of release from masking, one can suggest that school-age children have inherently poorer processing efficiency rather than temporal resolution.

Application of Monte Carlo algorithms to the Bayesian analysis of the Cosmic Microwave Background

NASA Technical Reports Server (NTRS)

Jewell, J.; Levin, S.; Anderson, C. H.

2004-01-01

Power spectrum estimation and evaluation of associated errors in the presence of incomplete sky coverage; nonhomogeneous, correlated instrumental noise; and foreground emission are problems of central importance for the extraction of cosmological information from the cosmic microwave background (CMB).

1024x1024 Pixel MWIR and LWIR QWIP Focal Plane Arrays and 320x256 MWIR:LWIR Pixel Colocated Simultaneous Dualband QWIP Focal Plane Arrays

NASA Technical Reports Server (NTRS)

Gunapala, Sarath D.; Bandara, Sumith V.; Liu, John K.; Hill, Cory J.; Rafol, S. B.; Mumolo, Jason M.; Trinh, Joseph T.; Tidrow, M. Z.; Le Van, P. D.

2005-01-01

Mid-wavelength infrared (MWIR) and long-wavelength infrared (LWIR) 1024x1024 pixel quantum well infrared photodetector (QWIP) focal planes have been demonstrated with excellent imaging performance. The MWIR QWIP detector array has demonstrated a noise equivalent differential temperature (NE(Delta)T) of 17 mK at a 95K operating temperature with f/2.5 optics at 300K background and the LWIR detector array has demonstrated a NE(Delta)T of 13 mK at a 70K operating temperature with the same optical and background conditions as the MWIR detector array after the subtraction of system noise. Both MWIR and LWIR focal planes have shown background limited performance (BLIP) at 90K and 70K operating-temperatures respectively, with similar optical and background conditions. In addition, we are in the process of developing MWIR and LWIR pixel collocated simultaneously readable dualband QWIP focal plane arrays.

Real time aircraft fly-over noise discrimination

NASA Astrophysics Data System (ADS)

Genescà, M.; Romeu, J.; Pàmies, T.; Sánchez, A.

2009-06-01

A method for measuring aircraft noise time history with automatic elimination of simultaneous urban noise is presented in this paper. A 3 m-long 12-microphone sparse array has been proven to give good performance in a wide range of urban placements. Nowadays, urban placements have to be avoided because their background noise has a great influence on the measurements made by sound level meters or single microphones. Because of the small device size and low number of microphones (that make it so easy to set up), the resolution of the device is not high enough to provide a clean aircraft noise time history by only applying frequency domain beamforming to the spatial cross-correlations of the microphones' signals. Therefore, a new step to the processing algorithm has been added to eliminate this handicap.

Adaptive aperture for Geiger mode avalanche photodiode flash ladar systems.

PubMed

Wang, Liang; Han, Shaokun; Xia, Wenze; Lei, Jieyu

2018-02-01

Although the Geiger-mode avalanche photodiode (GM-APD) flash ladar system offers the advantages of high sensitivity and simple construction, its detection performance is influenced not only by the incoming signal-to-noise ratio but also by the absolute number of noise photons. In this paper, we deduce a hyperbolic approximation to estimate the noise-photon number from the false-firing percentage in a GM-APD flash ladar system under dark conditions. By using this hyperbolic approximation function, we introduce a method to adapt the aperture to reduce the number of incoming background-noise photons. Finally, the simulation results show that the adaptive-aperture method decreases the false probability in all cases, increases the detection probability provided that the signal exceeds the noise, and decreases the average ranging error per frame.

Adaptive aperture for Geiger mode avalanche photodiode flash ladar systems

NASA Astrophysics Data System (ADS)

Wang, Liang; Han, Shaokun; Xia, Wenze; Lei, Jieyu

2018-02-01

Although the Geiger-mode avalanche photodiode (GM-APD) flash ladar system offers the advantages of high sensitivity and simple construction, its detection performance is influenced not only by the incoming signal-to-noise ratio but also by the absolute number of noise photons. In this paper, we deduce a hyperbolic approximation to estimate the noise-photon number from the false-firing percentage in a GM-APD flash ladar system under dark conditions. By using this hyperbolic approximation function, we introduce a method to adapt the aperture to reduce the number of incoming background-noise photons. Finally, the simulation results show that the adaptive-aperture method decreases the false probability in all cases, increases the detection probability provided that the signal exceeds the noise, and decreases the average ranging error per frame.

Biological impact of preschool music classes on processing speech in noise

PubMed Central

Strait, Dana L.; Parbery-Clark, Alexandra; O’Connell, Samantha; Kraus, Nina

2013-01-01

Musicians have increased resilience to the effects of noise on speech perception and its neural underpinnings. We do not know, however, how early in life these enhancements arise. We compared auditory brainstem responses to speech in noise in 32 preschool children, half of whom were engaged in music training. Thirteen children returned for testing one year later, permitting the first longitudinal assessment of subcortical auditory function with music training. Results indicate emerging neural enhancements in musically trained preschoolers for processing speech in noise. Longitudinal outcomes reveal that children enrolled in music classes experience further increased neural resilience to background noise following one year of continued training compared to nonmusician peers. Together, these data reveal enhanced development of neural mechanisms undergirding speech-in-noise perception in preschoolers undergoing music training and may indicate a biological impact of music training on auditory function during early childhood. PMID:23872199

Biological impact of preschool music classes on processing speech in noise.

PubMed

Strait, Dana L; Parbery-Clark, Alexandra; O'Connell, Samantha; Kraus, Nina

2013-10-01

Musicians have increased resilience to the effects of noise on speech perception and its neural underpinnings. We do not know, however, how early in life these enhancements arise. We compared auditory brainstem responses to speech in noise in 32 preschool children, half of whom were engaged in music training. Thirteen children returned for testing one year later, permitting the first longitudinal assessment of subcortical auditory function with music training. Results indicate emerging neural enhancements in musically trained preschoolers for processing speech in noise. Longitudinal outcomes reveal that children enrolled in music classes experience further increased neural resilience to background noise following one year of continued training compared to nonmusician peers. Together, these data reveal enhanced development of neural mechanisms undergirding speech-in-noise perception in preschoolers undergoing music training and may indicate a biological impact of music training on auditory function during early childhood. Copyright © 2013 Elsevier Ltd. All rights reserved.

Demonstration of improvement in the signal-to-noise ratio of Thomson scattering signal obtained by using a multi-pass optical cavity on the Tokyo Spherical Tokamak-2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Togashi, H., E-mail: togashi@fusion.k.u-tokyo.ac.jp; Ejiri, A.; Nakamura, K.

2014-11-15

The multi-pass Thomson scattering (TS) scheme enables obtaining many photons by accumulating multiple TS signals. The signal-to-noise ratio (SNR) depends on the accumulation number. In this study, we performed multi-pass TS measurements for ohmically heated plasmas, and the relationship between SNR and the accumulation number was investigated. As a result, improvement of SNR in this experiment indicated similar tendency to that calculated for the background noise dominant situation.

Correlated Photon-Pair Generation in Reverse Proton-Exchange PPLN Waveguides With Integrated Mode Demultiplexer at 10 GHz Clock

DTIC Science & Technology

2007-07-31

number of photon-pairs per pulse is μ ( 1<<μ ) and the laser repetition frequency isν . The average noise photon numbers per pulse are sμ and iμ for the...and 1563-nm center wavelength pass through a tunable bandpass filter to remove the background noise from the EDFA. The pump is then frequency doubled...generation in dispersion-shifted fiber: suppression of noise photons by cooling fiber", Opt. Express, 13, 7832 (2005) #83485 - $15.00 USD Received 29 May

Diagnostic techniques for measurement of aerodynamic noise in free field and reverberant environment of wind tunnels

NASA Technical Reports Server (NTRS)

El-Sum, H. M. A.; Mawardi, O. K.

1973-01-01

Techniques for studying aerodynamic noise generating mechanisms without disturbing the flow in a free field, and in the reverberation environment of the ARC wind tunnel were investigated along with the design and testing of an acoustic antenna with an electronic steering control. The acoustic characteristics of turbojet as a noise source, detection of direct sound from a source in a reverberant background, optical diagnostic methods, and the design characteristics of a high directivity acoustic antenna. Recommendations for further studies are included.

Acoustic Noise Levels of Dental Equipments and Its Association with Fear and Annoyance Levels among Patients Attending Different Dental Clinic Setups in Jaipur, India

PubMed Central

Ganta, Shravani; Nagaraj, Anup; Pareek, Sonia; Atri, Mansi; Singh, Kushpal; Sidiq, Mohsin

2014-01-01

Background: Noise is a source of pervasive occupational hazard for practicing dentists and the patients. The sources of dental sounds by various dental equipments can pose as a potential hazard to hearing system and add to the annoyance levels of the patients. The aim of the study was to analyze the noise levels from various equipments and evaluate the effect of acoustic noise stimulus on dental fear and annoyance levels among patients attending different dental clinic setups in Jaipur, India. Methodology: The sampling frame comprised of 180 patients, which included 90 patients attending 10 different private clinics and 90 patients attending a Dental College in Jaipur. The levels of Acoustic Noise Stimulus originating from different equipments were determined using a precision sound level meter/decibulometer. Dental fear among patients was measured using Dental Fear Scale (DFS). Results: Statistical analysis was performed using chi square test and unpaired t-test. The mean background noise levels were found to be maximum in the pre-clinical setup/ laboratory areas (69.23+2.20). Females and the patients attending dental college setup encountered more fear on seeing the drill as compared to the patients attending private clinics (p<0.001). Conclusion: The sources of dental sounds can pose as a potential hazard to hearing system. It was analyzed that the environment in the clinics can directly have an effect on the fear and annoyance levels of patients. Hence it is necessary control the noise from various dental equipments to reduce the fear of patients from visiting a dental clinic. PMID:24959512

Context-dependent effects of noise on echolocation pulse characteristics in free-tailed bats

PubMed Central

Smotherman, Michael S.

2010-01-01

Background noise evokes a similar suite of adaptations in the acoustic structure of communication calls across a diverse range of vertebrates. Echolocating bats may have evolved specialized vocal strategies for echolocating in noise, but also seem to exhibit generic vertebrate responses such as the ubiquitous Lombard response. We wondered how bats balance generic and echolocation-specific vocal responses to noise. To address this question, we first characterized the vocal responses of flying free-tailed bats (Tadarida brasiliensis) to broadband noises varying in amplitude. Secondly, we measured the bats’ responses to band-limited noises that varied in the extent of overlap with their echolocation pulse bandwidth. We hypothesized that the bats’ generic responses to noise would be graded proportionally with noise amplitude, total bandwidth and frequency content, and consequently that more selective responses to band-limited noise such as the jamming avoidance response could be explained by a linear decomposition of the response to broadband noise. Instead, the results showed that both the nature and the magnitude of the vocal responses varied with the acoustic structure of the outgoing pulse as well as non-linearly with noise parameters. We conclude that free-tailed bats utilize separate generic and specialized vocal responses to noise in a context-dependent fashion. PMID:19672604

Evidence of "hidden hearing loss" following noise exposures that produce robust TTS and ABR wave-I amplitude reductions.

PubMed

Lobarinas, Edward; Spankovich, Christopher; Le Prell, Colleen G

2017-06-01

In animals, noise exposures that produce robust temporary threshold shifts (TTS) can produce immediate damage to afferent synapses and long-term degeneration of low spontaneous rate auditory nerve fibers. This synaptopathic damage has been shown to correlate with reduced auditory brainstem response (ABR) wave-I amplitudes at suprathreshold levels. The perceptual consequences of this "synaptopathy" remain unknown but have been suggested to include compromised hearing performance in competing background noise. Here, we used a modified startle inhibition paradigm to evaluate whether noise exposures that produce robust TTS and ABR wave-I reduction but not permanent threshold shift (PTS) reduced hearing-in-noise performance. Animals exposed to 109 dB SPL octave band noise showed TTS >30 dB 24-h post noise and modest but persistent ABR wave-I reduction 2 weeks post noise despite full recovery of ABR thresholds. Hearing-in-noise performance was negatively affected by the noise exposure. However, the effect was observed only at the poorest signal to noise ratio and was frequency specific. Although TTS >30 dB 24-h post noise was a predictor of functional deficits, there was no relationship between the degree of ABR wave-I reduction and degree of functional impairment. Copyright © 2016 Elsevier B.V. All rights reserved.

Seismoelectric data processing for surface surveys of shallow targets

USGS Publications Warehouse

Haines, S.S.; Guitton, A.; Biondi, B.

2007-01-01

The utility of the seismoelectric method relies on the development of methods to extract the signal of interest from background and source-generated coherent noise that may be several orders-of-magnitude stronger. We compare data processing approaches to develop a sequence of preprocessing and signal/noise separation and to quantify the noise level from which we can extract signal events. Our preferred sequence begins with the removal of power line harmonic noise and the use of frequency filters to minimize random and source-generated noise. Mapping to the linear Radon domain with an inverse process incorporating a sparseness constraint provides good separation of signal from noise, though it is ineffective on noise that shows the same dip as the signal. Similarly, the seismoelectric signal and noise do not separate cleanly in the Fourier domain, so f-k filtering can not remove all of the source-generated noise and it also disrupts signal amplitude patterns. We find that prediction-error filters provide the most effective method to separate signal and noise, while also preserving amplitude information, assuming that adequate pattern models can be determined for the signal and noise. These Radon-domain and prediction-error-filter methods successfully separate signal from <33 dB stronger noise in our test data. ?? 2007 Society of Exploration Geophysicists.

Noise levels in primary schools of medium sized city in Greece.

PubMed

Sarantopoulos, George; Lykoudis, Spyros; Kassomenos, Pavlos

2014-06-01

This study presents and evaluates noise levels recorded at 15 school complexes in order to describe the indoor as well as the outdoor acoustic environment of schools and gain insight on controlling factors. Noise levels at the roadside in front of the school, the schoolyard, and 41 classrooms, both occupied and unoccupied, were simultaneously and continuously recorded through the course of a daily timetable (08:20-13:10). The average speech noise level of teachers was separately measured for 1min periods. Indoor noise levels, in all cases, were much higher than internationally recommended values: LAeq,5min averaged 69.0dB in occupied classrooms, and 47.1dB in unoccupied ones. Average speech-to-noise ratio (SNR) was estimated to be 12.0dB(A) during teaching, whereas both indoor and outdoor noise levels were significantly elevated during break time and outdoor physical-educational activities. Corresponding measurements of indoor and outdoor noise suggest that noise from the outside (road and schoolyard) affects the background noise level in the classrooms, however in varying degrees, depending on the specific layout and road traffic characteristics. Using double glazing diminishes this effect. © 2013.

Auditory Verbal Working Memory as a Predictor of Speech Perception in Modulated Maskers in Listeners with Normal Hearing

ERIC Educational Resources Information Center

Millman, Rebecca E.; Mattys, Sven L.

2017-01-01

Purpose: Background noise can interfere with our ability to understand speech. Working memory capacity (WMC) has been shown to contribute to the perception of speech in modulated noise maskers. WMC has been assessed with a variety of auditory and visual tests, often pertaining to different components of working memory. This study assessed the…

Hadfield installing UBNT Sensors in the U.S. Laboratory

NASA Image and Video Library

2013-02-01

ISS034-E-038211 (1 Feb. 2013) --- Canadian Space Agency astronaut Chris Hadfield, Expedition 34 flight engineer, installs Ultra-Sonic Background Noise Tests (UBNT) sensors behind a rack in the Destiny laboratory, using the International Space Station (ISS) as Testbed for Analog Research (ISTAR) procedures. These sensors detect high frequency noise levels generated by ISS hardware and equipment operating within Destiny.

Integrated Spacesuit Audio System Enhances Speech Quality and Reduces Noise

NASA Technical Reports Server (NTRS)

Huang, Yiteng Arden; Chen, Jingdong; Chen, Shaoyan Sharyl

2009-01-01

A new approach has been proposed for increasing astronaut comfort and speech capture. Currently, the special design of a spacesuit forms an extreme acoustic environment making it difficult to capture clear speech without compromising comfort. The proposed Integrated Spacesuit Audio (ISA) system is to incorporate the microphones into the helmet and use software to extract voice signals from background noise.

USAF Space Sensing Cryogenic Considerations

DTIC Science & Technology

2010-01-01

Background IR emissions and electronic noise that is inherently present in Focal Plane Arrays (FPAs) and surveillance optics bench designs prevents their use... noise that is inherently present in Focal Plane Arrays (FPAs) and surveillance optics bench designs prevents their use unless they are cooled to...experimental or not of sufficient sensitivity for the before mentioned missions [2]. Examples include Quantum Well IR Photodetectors ( QWIP ), nanotubes

Background noise levels measured in the NASA Lewis 9- by 15-foot low-speed wind tunnel

NASA Technical Reports Server (NTRS)

Woodward, Richard P.; Dittmar, James H.; Hall, David G.; Kee-Bowling, Bonnie

1994-01-01

The acoustic capability of the NASA Lewis 9 by 15 Foot Low Speed Wind Tunnel has been significantly improved by reducing the background noise levels measured by in-flow microphones. This was accomplished by incorporating streamlined microphone holders having a profile developed by researchers at the NASA Ames Research Center. These new holders were fabricated for fixed mounting on the tunnel wall and for an axially traversing microphone probe which was mounted to the tunnel floor. Measured in-flow noise levels in the tunnel test section were reduced by about 10 dB with the new microphone holders compared with those measured with the older, less refined microphone holders. Wake interference patterns between fixed wall microphones were measured and resulted in preferred placement patterns for these microphones to minimize these effects. Acoustic data from a model turbofan operating in the tunnel test section showed that results for the fixed and translating microphones were equivalent for common azimuthal angles, suggesting that the translating microphone probe, with its significantly greater angular resolution, is preferred for sideline noise measurements. Fixed microphones can provide a local check on the traversing microphone data quality, and record acoustic performance at other azimuthal angles.

Improving the signal analysis for in vivo photoacoustic flow cytometry

NASA Astrophysics Data System (ADS)

Niu, Zhenyu; Yang, Ping; Wei, Dan; Tang, Shuo; Wei, Xunbin

2015-03-01

At early stage of cancer, a small number of circulating tumor cells (CTCs) appear in the blood circulation. Thus, early detection of malignant circulating tumor cells has great significance for timely treatment to reduce the cancer death rate. We have developed an in vivo photoacoustic flow cytometry (PAFC) to monitor the metastatic process of CTCs and record the signals from target cells. Information of target cells which is helpful to the early therapy would be obtained through analyzing and processing the signals. The raw signal detected from target cells often contains some noise caused by electronic devices, such as background noise and thermal noise. We choose the Wavelet denoising method to effectively distinguish the target signal from background noise. Processing in time domain and frequency domain would be combined to analyze the signal after denoising. This algorithm contains time domain filter and frequency transformation. The frequency spectrum image of the signal contains distinctive features that can be used to analyze the property of target cells or particles. The PAFC technique can detect signals from circulating tumor cells or other particles. The processing methods have a great potential for analyzing signals accurately and rapidly.

Adaptive spatial filtering of daytime sky noise in a satellite quantum key distribution downlink receiver

NASA Astrophysics Data System (ADS)

Gruneisen, Mark T.; Sickmiller, Brett A.; Flanagan, Michael B.; Black, James P.; Stoltenberg, Kurt E.; Duchane, Alexander W.

2016-02-01

Spatial filtering is an important technique for reducing sky background noise in a satellite quantum key distribution downlink receiver. Atmospheric turbulence limits the extent to which spatial filtering can reduce sky noise without introducing signal losses. Using atmospheric propagation and compensation simulations, the potential benefit of adaptive optics (AO) to secure key generation (SKG) is quantified. Simulations are performed assuming optical propagation from a low-Earth-orbit satellite to a terrestrial receiver that includes AO. Higher-order AO correction is modeled assuming a Shack-Hartmann wavefront sensor and a continuous-face-sheet deformable mirror. The effects of atmospheric turbulence, tracking, and higher-order AO on the photon capture efficiency are simulated using statistical representations of turbulence and a time-domain wave-optics hardware emulator. SKG rates are calculated for a decoy-state protocol as a function of the receiver field of view for various strengths of turbulence, sky radiances, and pointing angles. The results show that at fields of view smaller than those discussed by others, AO technologies can enhance SKG rates in daylight and enable SKG where it would otherwise be prohibited as a consequence of background optical noise and signal loss due to propagation and turbulence effects.

Effects of background noise on acoustic characteristics of Bengalese finch songs.

PubMed

Shiba, Shintaro; Okanoya, Kazuo; Tachibana, Ryosuke O

2016-12-01

Online regulation of vocalization in response to auditory feedback is one of the essential issues for vocal communication. One such audio-vocal interaction is the Lombard effect, an involuntary increase in vocal amplitude in response to the presence of background noise. Along with vocal amplitude, other acoustic characteristics, including fundamental frequency (F0), also change in some species. Bengalese finches (Lonchura striata var. domestica) are a suitable model for comparative, ethological, and neuroscientific studies on audio-vocal interaction because they require real-time auditory feedback of their own songs to maintain normal singing. Here, the changes in amplitude and F0 with a focus on the distinct song elements (i.e., notes) of Bengalese finches under noise presentation are demonstrated. To accurately analyze these acoustic characteristics, two different bandpass-filtered noises at two levels of sound intensity were used. The results confirmed that the Lombard effect occurs at the note level of Bengalese finch song. Further, individually specific modes of changes in F0 are shown. These behavioral changes suggested the vocal control mechanisms on which the auditory feedback is based have a predictable effect on amplitude, but complex spectral effects on individual note production.

Microwave SQUID Multiplexer Demonstration for Cosmic Microwave Background Imagers.

PubMed

Dober, B; Becker, D T; Bennett, D A; Bryan, S A; Duff, S M; Gard, J D; Hays-Wehle, J P; Hilton, G C; Hubmayr, J; Mates, J A B; Reintsema, C D; Vale, L R; Ullom, J N

2017-12-01

Key performance characteristics are demonstrated for the microwave SQUID multiplexer (µmux) coupled to transition edge sensor (TES) bolometers that have been optimized for cosmic microwave background (CMB) observations. In a 64-channel demonstration, we show that the µmux produces a white, input referred current noise level of [Formula: see text] at -77 dB microwave probe tone power, which is well below expected fundamental detector and photon noise sources for a ground-based CMB-optimized bolometer. Operated with negligible photon loading, we measure [Formula: see text] in the TES-coupled channels biased at 65% of the sensor normal resistance. This noise level is consistent with that predicted from bolometer thermal fluctuation (i.e. phonon) noise. Furthermore, the power spectral density is white over a range of frequencies down to ~ 100 mHz, which enables CMB mapping on large angular scales that constrain the physics of inflation. Additionally, we report cross-talk measurements that indicate a level below 0.3%, which is less than the level of cross-talk from multiplexed readout systems in deployed CMB imagers. These measurements demonstrate the µmux as a viable readout technique for future CMB imaging instruments.

Energy-Based Wavelet De-Noising of Hydrologic Time Series

PubMed Central

Sang, Yan-Fang; Liu, Changming; Wang, Zhonggen; Wen, Jun; Shang, Lunyu

2014-01-01

De-noising is a substantial issue in hydrologic time series analysis, but it is a difficult task due to the defect of methods. In this paper an energy-based wavelet de-noising method was proposed. It is to remove noise by comparing energy distribution of series with the background energy distribution, which is established from Monte-Carlo test. Differing from wavelet threshold de-noising (WTD) method with the basis of wavelet coefficient thresholding, the proposed method is based on energy distribution of series. It can distinguish noise from deterministic components in series, and uncertainty of de-noising result can be quantitatively estimated using proper confidence interval, but WTD method cannot do this. Analysis of both synthetic and observed series verified the comparable power of the proposed method and WTD, but de-noising process by the former is more easily operable. The results also indicate the influences of three key factors (wavelet choice, decomposition level choice and noise content) on wavelet de-noising. Wavelet should be carefully chosen when using the proposed method. The suitable decomposition level for wavelet de-noising should correspond to series' deterministic sub-signal which has the smallest temporal scale. If too much noise is included in a series, accurate de-noising result cannot be obtained by the proposed method or WTD, but the series would show pure random but not autocorrelation characters, so de-noising is no longer needed. PMID:25360533

Musical training during early childhood enhances the neural encoding of speech in noise

PubMed Central

Strait, Dana L.; Parbery-Clark, Alexandra; Hittner, Emily; Kraus, Nina

2012-01-01

For children, learning often occurs in the presence of background noise. As such, there is growing desire to improve a child’s access to a target signal in noise. Given adult musicians’ perceptual and neural speech-in-noise enhancements, we asked whether similar effects are present in musically-trained children. We assessed the perception and subcortical processing of speech in noise and related cognitive abilities in musician and nonmusician children that were matched for a variety of overarching factors. Outcomes reveal that musicians’ advantages for processing speech in noise are present during pivotal developmental years. Supported by correlations between auditory working memory and attention and auditory brainstem response properties, we propose that musicians’ perceptual and neural enhancements are driven in a top-down manner by strengthened cognitive abilities with training. Our results may be considered by professionals involved in the remediation of language-based learning deficits, which are often characterized by poor speech perception in noise. PMID:23102977

Noise removal in extended depth of field microscope images through nonlinear signal processing.

PubMed

Zahreddine, Ramzi N; Cormack, Robert H; Cogswell, Carol J

2013-04-01

Extended depth of field (EDF) microscopy, achieved through computational optics, allows for real-time 3D imaging of live cell dynamics. EDF is achieved through a combination of point spread function engineering and digital image processing. A linear Wiener filter has been conventionally used to deconvolve the image, but it suffers from high frequency noise amplification and processing artifacts. A nonlinear processing scheme is proposed which extends the depth of field while minimizing background noise. The nonlinear filter is generated via a training algorithm and an iterative optimizer. Biological microscope images processed with the nonlinear filter show a significant improvement in image quality and signal-to-noise ratio over the conventional linear filter.

A parametric symmetry breaking transducer

NASA Astrophysics Data System (ADS)

Eichler, Alexander; Heugel, Toni L.; Leuch, Anina; Degen, Christian L.; Chitra, R.; Zilberberg, Oded

2018-06-01

Force detectors rely on resonators to transduce forces into a readable signal. Usually, these resonators operate in the linear regime and their signal appears amidst a competing background comprising thermal or quantum fluctuations as well as readout noise. Here, we demonstrate a parametric symmetry breaking transduction method that leads to a robust nonlinear force detection in the presence of noise. The force signal is encoded in the frequency at which the system jumps between two phase states which are inherently protected against phase noise. Consequently, the transduction effectively decouples from readout noise channels. For a controlled demonstration of the method, we experiment with a macroscopic doubly clamped string. Our method provides a promising paradigm for high-precision force detection.

Reconstruction of pulse noisy images via stochastic resonance

PubMed Central

Han, Jing; Liu, Hongjun; Sun, Qibing; Huang, Nan

2015-01-01

We investigate a practical technology for reconstructing nanosecond pulse noisy images via stochastic resonance, which is based on the modulation instability. A theoretical model of this method for optical pulse signal is built to effectively recover the pulse image. The nanosecond noise-hidden images grow at the expense of noise during the stochastic resonance process in a photorefractive medium. The properties of output images are mainly determined by the input signal-to-noise intensity ratio, the applied voltage across the medium, and the correlation length of noise background. A high cross-correlation gain is obtained by optimizing these parameters. This provides a potential method for detecting low-level or hidden pulse images in various imaging applications. PMID:26067911

Image denoising for real-time MRI.

PubMed

Klosowski, Jakob; Frahm, Jens

2017-03-01

To develop an image noise filter suitable for MRI in real time (acquisition and display), which preserves small isolated details and efficiently removes background noise without introducing blur, smearing, or patch artifacts. The proposed method extends the nonlocal means algorithm to adapt the influence of the original pixel value according to a simple measure for patch regularity. Detail preservation is improved by a compactly supported weighting kernel that closely approximates the commonly used exponential weight, while an oracle step ensures efficient background noise removal. Denoising experiments were conducted on real-time images of healthy subjects reconstructed by regularized nonlinear inversion from radial acquisitions with pronounced undersampling. The filter leads to a signal-to-noise ratio (SNR) improvement of at least 60% without noticeable artifacts or loss of detail. The method visually compares to more complex state-of-the-art filters as the block-matching three-dimensional filter and in certain cases better matches the underlying noise model. Acceleration of the computation to more than 100 complex frames per second using graphics processing units is straightforward. The sensitivity of nonlocal means to small details can be significantly increased by the simple strategies presented here, which allows partial restoration of SNR in iteratively reconstructed images without introducing a noticeable time delay or image artifacts. Magn Reson Med 77:1340-1352, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

Advanced Water Vapor Lidar Detection System

NASA Technical Reports Server (NTRS)

Elsayed-Ali, Hani

1998-01-01

In the present water vapor lidar system, the detected signal is sent over long cables to a waveform digitizer in a CAMAC crate. This has the disadvantage of transmitting analog signals for a relatively long distance, which is subjected to pickup noise, leading to a decrease in the signal to noise ratio. Generally, errors in the measurement of water vapor with the DIAL method arise from both random and systematic sources. Systematic errors in DIAL measurements are caused by both atmospheric and instrumentation effects. The selection of the on-line alexandrite laser with a narrow linewidth, suitable intensity and high spectral purity, and its operation at the center of the water vapor lines, ensures minimum influence in the DIAL measurement that are caused by the laser spectral distribution and avoid system overloads. Random errors are caused by noise in the detected signal. Variability of the photon statistics in the lidar return signal, noise resulting from detector dark current, and noise in the background signal are the main sources of random error. This type of error can be minimized by maximizing the signal to noise ratio. The increase in the signal to noise ratio can be achieved by several ways. One way is to increase the laser pulse energy, by increasing its amplitude or the pulse repetition rate. Another way, is to use a detector system with higher quantum efficiency and lower noise, on the other hand, the selection of a narrow band optical filter that rejects most of the day background light and retains high optical efficiency is an important issue. Following acquisition of the lidar data, we minimize random errors in the DIAL measurement by averaging the data, but this will result in the reduction of the vertical and horizontal resolutions. Thus, a trade off is necessary to achieve a balance between the spatial resolution and the measurement precision. Therefore, the main goal of this research effort is to increase the signal to noise ratio by a factor of 10 over the current system, using a newly evaluated, very low noise avalanche photo diode detector and constructing a 10 MHz waveform digitizer which will replace the current CAMAC system.

Monte Carlo Algorithms for a Bayesian Analysis of the Cosmic Microwave Background

NASA Technical Reports Server (NTRS)

Jewell, Jeffrey B.; Eriksen, H. K.; ODwyer, I. J.; Wandelt, B. D.; Gorski, K.; Knox, L.; Chu, M.

2006-01-01

A viewgraph presentation on the review of Bayesian approach to Cosmic Microwave Background (CMB) analysis, numerical implementation with Gibbs sampling, a summary of application to WMAP I and work in progress with generalizations to polarization, foregrounds, asymmetric beams, and 1/f noise is given.

Long-Range Correlation in alpha-Wave Predominant EEG in Human

NASA Astrophysics Data System (ADS)

Sharif, Asif; Chyan Lin, Der; Kwan, Hon; Borette, D. S.

2004-03-01

The background noise in the alpha-predominant EEG taken from eyes-open and eyes-closed neurophysiological states is studied. Scale-free characteristic is found in both cases using the wavelet approach developed by Simonsen and Nes [1]. The numerical results further show the scaling exponent during eyes-closed is consistently lower than eyes-open. We conjecture the origin of this difference is related to the temporal reconfiguration of the neural network in the brain. To further investigate the scaling structure of the EEG background noise, we extended the second order statistics to higher order moments using the EEG increment process. We found that the background fluctuation in the alpha-predominant EEG is predominantly monofractal. Preliminary results are given to support this finding and its implication in brain functioning is discussed. [1] A.H. Simonsen and O.M. Nes, Physical Review E, 58, 2779¡V2748 (1998).

Estimating and Separating Noise from AIA Images

NASA Astrophysics Data System (ADS)

Kirk, Michael S.; Ireland, Jack; Young, C. Alex; Pesnell, W. Dean

2016-10-01

All digital images are corrupted by noise and SDO AIA is no different. In most solar imaging, we have the luxury of high photon counts and low background contamination, which when combined with carful calibration, minimize much of the impact noise has on the measurement. Outside high-intensity regions, such as in coronal holes, the noise component can become significant and complicate feature recognition and segmentation. We create a practical estimate of noise in the high-resolution AIA images across the detector CCD in all seven EUV wavelengths. A mixture of Poisson and Gaussian noise is well suited in the digital imaging environment due to the statistical distributions of photons and the characteristics of the CCD. Using state-of-the-art noise estimation techniques, the publicly available solar images, and coronal loop simulations; we construct a maximum-a-posteriori assessment of the error in these images. The estimation and mitigation of noise not only provides a clearer view of large-scale solar structure in the solar corona, but also provides physical constraints on fleeting EUV features observed with AIA.

Noise abatement and traffic safety: The trade-off of quieter engines and pavements on vehicle detection.

PubMed

Mendonça, C; Freitas, E; Ferreira, J P; Raimundo, I D; Santos, J A

2013-03-01

Road traffic sounds are a major source of noise pollution in urban areas. But recent developments such as low noise pavements and hybrid/electric engine vehicles cast an optimistic outlook over such an environmental problem. However, it can be argued that engine, tire, and road noise could be relevant sources of information to avoid road traffic conflicts and accidents. In this paper, we analyze the potential trade-offs of traffic-noise abatement approaches in an experimental study, focusing for the first time on the impact and interaction of relevant factors such as pavement type, vehicle type, listener's age, and background noise, on vehicle detection levels. Results reveal that vehicle and pavement type significantly affect vehicle detection. Age is a significant factor, as both younger and older people exhibit lower detection levels of incoming vehicles. Low noise pavements combined with all-electric and hybrid vehicles might pose a severe threat to the safety of vulnerable road users. All factors interact simultaneously, and vehicle detection is best predicted by the loudness signal-to-noise ratio. Copyright © 2012 Elsevier Ltd. All rights reserved.

An evaluation of noise and its effects on shuttle crewmembers during STS-50/USML-1

NASA Technical Reports Server (NTRS)

Koros, Anton; Wheelwright, Charles; Adam, Susan

1993-01-01

High noise levels can lead to physiological, psychological, and performance effects in man, ranging from irritability, annoyance, and sleep interference to interference with verbal communication and fatigue, and to temporary or permanent threshold shift at more extreme levels. The current study evaluated the acoustic environment of the STS50/USML-1 mission. The major objectives were to gain subjective assessments of the STS-50 noise levels, document impacts of noise upon crewmember performance, collect inflight sound level measurements, compare noise levels across missions, evaluate the current Shuttle acoustic criterion, and to make recommendations regarding noise specifications for SSF and other long-duration manned space missions. Sound measurements indicated that background noise levels were 60, 64, and 61 A-weighted decibels, respectively, on the Orbiter middeck, flight deck, and Space lab. All levels were rated acceptable, with the Spacelab environment rated the most favorably. Sleep stations afforded attenuation from airborne noise sources, although all crewmembers reported being awakened by crew activity on the middeck. Models of distance for acceptable speech communications were generated, identifying situations of compromised verbal communications to be avoided.

Enhanced low-noise gain from InAs avalanche photodiodes with reduced dark current and background doping

NASA Astrophysics Data System (ADS)

Maddox, S. J.; Sun, W.; Lu, Z.; Nair, H. P.; Campbell, J. C.; Bank, S. R.

2012-10-01

We reduced the room temperature dark current in an InAs avalanche photodiode by increasing the p-type contact doping, resulting in an increased energetic barrier to minority electron injection into the p-region, which is a significant source of dark current at room temperature. In addition, by improving the molecular beam epitaxy growth conditions, we reduced the background doping concentration and realized depletion widths as wide as 5 μm at reverse biases as low as 1.5 V. These improvements culminated in low-noise InAs avalanche photodiodes exhibiting a room temperature multiplication gain of ˜80, at a record low reverse bias of 12 V.

Minimum resolvable power contrast model

NASA Astrophysics Data System (ADS)

Qian, Shuai; Wang, Xia; Zhou, Jingjing

2018-01-01

Signal-to-noise ratio and MTF are important indexs to evaluate the performance of optical systems. However,whether they are used alone or joint assessment cannot intuitively describe the overall performance of the system. Therefore, an index is proposed to reflect the comprehensive system performance-Minimum Resolvable Radiation Performance Contrast (MRP) model. MRP is an evaluation model without human eyes. It starts from the radiance of the target and the background, transforms the target and background into the equivalent strips,and considers attenuation of the atmosphere, the optical imaging system, and the detector. Combining with the signal-to-noise ratio and the MTF, the Minimum Resolvable Radiation Performance Contrast is obtained. Finally the detection probability model of MRP is given.

Assessment of a directional microphone array for hearing-impaired listeners.

PubMed

Soede, W; Bilsen, F A; Berkhout, A J

1993-08-01

Hearing-impaired listeners often have great difficulty understanding speech in surroundings with background noise or reverberation. Based on array techniques, two microphone prototypes (broadside and endfire) have been developed with strongly directional characteristics [Soede et al., "Development of a new directional hearing instrument based on array technology," J. Acoust. Soc. Am. 94, 785-798 (1993)]. Physical measurements show that the arrays attenuate reverberant sound by 6 dB (free-field) and can improve the signal-to-noise ratio by 7 dB in a diffuse noise field (measured with a KEMAR manikin). For the clinical assessment of these microphones an experimental setup was made in a sound-insulated listening room with one loudspeaker in front of the listener simulating the partner in a discussion and eight loudspeakers placed on the edges of a cube producing a diffuse background noise. The hearing-impaired subject wearing his own (familiar) hearing aid is placed in the center of the cube. The speech-reception threshold in noise for simple Dutch sentences was determined with a normal single omnidirectional microphone and with one of the microphone arrays. The results of monaural listening tests with hearing impaired subjects show that in comparison with an omnidirectional hearing-aid microphone the broadside and endfire microphone array gives a mean improvement of the speech reception threshold in noise of 7.0 dB (26 subjects) and 6.8 dB (27 subjects), respectively. Binaural listening with two endfire microphone arrays gives a binaural improvement which is comparable to the binaural improvement obtained by listening with two normal ears or two conventional hearing aids.

Estimating rate uncertainty with maximum likelihood: differences between power-law and flicker–random-walk models

USGS Publications Warehouse

Langbein, John O.

2012-01-01

Recent studies have documented that global positioning system (GPS) time series of position estimates have temporal correlations which have been modeled as a combination of power-law and white noise processes. When estimating quantities such as a constant rate from GPS time series data, the estimated uncertainties on these quantities are more realistic when using a noise model that includes temporal correlations than simply assuming temporally uncorrelated noise. However, the choice of the specific representation of correlated noise can affect the estimate of uncertainty. For many GPS time series, the background noise can be represented by either: (1) a sum of flicker and random-walk noise or, (2) as a power-law noise model that represents an average of the flicker and random-walk noise. For instance, if the underlying noise model is a combination of flicker and random-walk noise, then incorrectly choosing the power-law model could underestimate the rate uncertainty by a factor of two. Distinguishing between the two alternate noise models is difficult since the flicker component can dominate the assessment of the noise properties because it is spread over a significant portion of the measurable frequency band. But, although not necessarily detectable, the random-walk component can be a major constituent of the estimated rate uncertainty. None the less, it is possible to determine the upper bound on the random-walk noise.

Wind noise in hearing aids with directional and omnidirectional microphones: polar characteristics of behind-the-ear hearing aids.

PubMed

Chung, King; Mongeau, Luc; McKibben, Nicholas

2009-04-01

Wind noise can be a significant problem for hearing instrument users. This study examined the polar characteristics of flow noise at outputs of two behind-the-ear digital hearing aids, and a microphone mounted on the surface of a cylinder at flow velocities ranging from a gentle breeze (4.5 m/s) to a strong gale (22.5 m/s) . The hearing aids were programed in an anechoic chamber, and tested in a quiet wind tunnel for flow noise recordings. Flow noise levels were estimated by normalizing the overall gain of the hearing aids to 0 dB. The results indicated that the two hearing aids had similar flow noise characteristics: The noise level was generally the lowest when the microphone faced upstream, higher when the microphone faced downstream, and the highest for frontal and rearward incidence angles. Directional microphones often generated higher flow noise level than omnidirectional microphones but they could reduce far-field background noise, resulting in a lower ambient noise level than omnidirectional microphones. Data for the academic microphone- on-cylinder configuration suggested that both turbulence and flow impingement might have contributed to the generation of flow noise in the hearing aids. Clinical and engineering design applications are discussed.

The effects of environmental and classroom noise on the academic attainments of primary school children.

PubMed

Shield, Bridget M; Dockrell, Julie E

2008-01-01

While at school children are exposed to various types of noise including external, environmental noise and noise generated within the classroom. Previous research has shown that noise has detrimental effects upon children's performance at school, including reduced memory, motivation, and reading ability. In England and Wales, children's academic performance is assessed using standardized tests of literacy, mathematics, and science. A study has been conducted to examine the impact, if any, of chronic exposure to external and internal noise on the test results of children aged 7 and 11 in London (UK) primary schools. External noise was found to have a significant negative impact upon performance, the effect being greater for the older children. The analysis suggested that children are particularly affected by the noise of individual external events. Test scores were also affected by internal classroom noise, background levels being significantly related to test results. Negative relationships between performance and noise levels were maintained when the data were corrected for socio-economic factors relating to social deprivation, language, and special educational needs. Linear regression analysis has been used to estimate the maximum levels of external and internal noise which allow the schools surveyed to achieve required standards of literacy and numeracy.

Molecular dynamics of alamethicin transmembrane channels from open-channel current noise analysis.

PubMed

Mak, D O; Webb, W W

1995-12-01

Conductance noise measurement of the open states of alamethicin transmembrane channels reveals excess noise attributable to cooperative low-frequency molecular dynamics that can generate fluctuations approximately 1 A rms in the effective channel pore radius. Single-channel currents through both persistent and nonpersistent channels with multiple conductance states formed by purified polypeptide alamethicin in artificial phospholipid bilayers isolated onto micropipettes with gigaohm seals were recorded using a voltage-clamp technique with low background noise (rms noise < 3 pA up to 20 kHz). Current noise power spectra between 100 Hz and 20 kHz of each open channel state showed little frequency dependence. Noise from undetected conductance state transitions was insignificant. Johnson and shot noises were evaluated. Current noise caused by electrolyte concentration fluctuation via diffusion was isolated by its dependence on buffer concentration. After removing these contributions, significant current noise remains in all persistent channel states and increases in higher conductance states. In nonpersistent channels, remaining noise occurs primarily in the lowest two states. These fluctuations of channel conductance are attributed to thermal oscillations of the channel molecular conformation and are modeled as a Langevin translational oscillation of alamethicin molecules moving radially from the channel pore, damped mostly by lipid bilayer viscosity.

[Equivalent continuous noise level in neonatal intensive care unit associated to burnout syndrome].

PubMed

Garrido Galindo, A P; Camargo Caicedo, Y; Vélez-Pereira, A M

2015-01-01

Noise levels in neonatal intensive care units allow the appearance of symptoms associated with burnout such as stress, irritability, fatigue and emotional instability on health care personnel. The aim of this study was to evaluate the equivalent continuous noise levels in the neonatal intensive care unit and compare the results with noise levels associated with the occurrence of burnout syndrome on the care team. Continuous sampling was conducted for 20 days using a type I sound level meter on the unit. The maximum, the ninetieth percentile and the equivalent continuous noise level (Leq) values were recorded. Noise level is reported in the range of 51.4-77.6 decibels A (dBA) with an average of 64 dBA, 100.6 dBA maximum, and average background noise from 57.9 dBA. Noise levels exceed the standards suggested for neonatal intensive care units, are close to maximum values referred for noise exposure in the occupational standards and to noise levels associated with the onset of burnout; thus allowing to infer the probability of occurrence of high levels of noise present in the unit on the development of burnout in caregivers. Copyright © 2013 Elsevier España, S.L.U. y SEEIUC. All rights reserved.

Preprocessing of 2-Dimensional Gel Electrophoresis Images Applied to Proteomic Analysis: A Review.

PubMed

Goez, Manuel Mauricio; Torres-Madroñero, Maria Constanza; Röthlisberger, Sarah; Delgado-Trejos, Edilson

2018-02-01

Various methods and specialized software programs are available for processing two-dimensional gel electrophoresis (2-DGE) images. However, due to the anomalies present in these images, a reliable, automated, and highly reproducible system for 2-DGE image analysis has still not been achieved. The most common anomalies found in 2-DGE images include vertical and horizontal streaking, fuzzy spots, and background noise, which greatly complicate computational analysis. In this paper, we review the preprocessing techniques applied to 2-DGE images for noise reduction, intensity normalization, and background correction. We also present a quantitative comparison of non-linear filtering techniques applied to synthetic gel images, through analyzing the performance of the filters under specific conditions. Synthetic proteins were modeled into a two-dimensional Gaussian distribution with adjustable parameters for changing the size, intensity, and degradation. Three types of noise were added to the images: Gaussian, Rayleigh, and exponential, with signal-to-noise ratios (SNRs) ranging 8-20 decibels (dB). We compared the performance of wavelet, contourlet, total variation (TV), and wavelet-total variation (WTTV) techniques using parameters SNR and spot efficiency. In terms of spot efficiency, contourlet and TV were more sensitive to noise than wavelet and WTTV. Wavelet worked the best for images with SNR ranging 10-20 dB, whereas WTTV performed better with high noise levels. Wavelet also presented the best performance with any level of Gaussian noise and low levels (20-14 dB) of Rayleigh and exponential noise in terms of SNR. Finally, the performance of the non-linear filtering techniques was evaluated using a real 2-DGE image with previously identified proteins marked. Wavelet achieved the best detection rate for the real image. Copyright © 2018 Beijing Institute of Genomics, Chinese Academy of Sciences and Genetics Society of China. Production and hosting by Elsevier B.V. All rights reserved.

The extraction of spot signal in Shack-Hartmann wavefront sensor based on sparse representation

NASA Astrophysics Data System (ADS)

Zhang, Yanyan; Xu, Wentao; Chen, Suting; Ge, Junxiang; Wan, Fayu

2016-07-01

Several techniques have been used with Shack-Hartmann wavefront sensors to determine the local wave-front gradient across each lenslet. While the centroid error of Shack-Hartmann wavefront sensor is relatively large since the skylight background and the detector noise. In this paper, we introduce a new method based on sparse representation to extract the target signal from the background and the noise. First, an over complete dictionary of the spot signal is constructed based on two-dimensional Gaussian model. Then the Shack-Hartmann image is divided into sub blocks. The corresponding coefficients of each block is computed in the over complete dictionary. Since the coefficients of the noise and the target are large different, then extract the target by setting a threshold to the coefficients. Experimental results show that the target can be well extracted and the deviation, RMS and PV of the centroid are all smaller than the method of subtracting threshold.

Correcting geometric and photometric distortion of document images on a smartphone

NASA Astrophysics Data System (ADS)

Simon, Christian; Williem; Park, In Kyu

2015-01-01

A set of document image processing algorithms for improving the optical character recognition (OCR) capability of smartphone applications is presented. The scope of the problem covers the geometric and photometric distortion correction of document images. The proposed framework was developed to satisfy industrial requirements. It is implemented on an off-the-shelf smartphone with limited resources in terms of speed and memory. Geometric distortions, i.e., skew and perspective distortion, are corrected by sending horizontal and vertical vanishing points toward infinity in a downsampled image. Photometric distortion includes image degradation from moiré pattern noise and specular highlights. Moiré pattern noise is removed using low-pass filters with different sizes independently applied to the background and text region. The contrast of the text in a specular highlighted area is enhanced by locally enlarging the intensity difference between the background and text while the noise is suppressed. Intensive experiments indicate that the proposed methods show a consistent and robust performance on a smartphone with a runtime of less than 1 s.

Simulating environmental and psychological acoustic factors of the operating room.

PubMed

Bennett, Christopher L; Dudaryk, Roman; Ayers, Andrew L; McNeer, Richard R

2015-12-01

In this study, an operating room simulation environment was adapted to include quadraphonic speakers, which were used to recreate a composed clinical soundscape. To assess validity of the composed soundscape, several acoustic parameters of this simulated environment were acquired in the presence of alarms only, background noise only, or both. These parameters were also measured for comparison from size-matched operating rooms at Jackson Memorial Hospital. The parameters examined included sound level, reverberation time, and predictive metrics of speech intelligibility in quiet and noise. It was found that the sound levels and acoustic parameters were comparable between the simulated environment and the actual operating rooms. The impact of the background noise on the perception of medical alarms was then examined, and was found to have little impact on the audibility of the alarms. This study is a first in kind report of a comparison between the environmental and psychological acoustical parameters of a hospital simulation environment and actual operating rooms.

A Portable Infrasonic Detection System

NASA Technical Reports Server (NTRS)

Shams, Qamar A.; Burkett, Cecil G.; Zuckerwar, Allan J.; Lawrenson, Christopher C.; Masterman, Michael

2008-01-01

During last couple of years, NASA Langley has designed and developed a portable infrasonic detection system which can be used to make useful infrasound measurements at a location where it was not possible previously. The system comprises an electret condenser microphone, having a 3-inch membrane diameter, and a small, compact windscreen. Electret-based technology offers the lowest possible background noise, because Johnson noise generated in the supporting electronics (preamplifier) is minimized. The microphone features a high membrane compliance with a large backchamber volume, a prepolarized backplane and a high impedance preamplifier located inside the backchamber. The windscreen, based on the high transmission coefficient of infrasound through matter, is made of a material having a low acoustic impedance and sufficiently thick wall to insure structural stability. Close-cell polyurethane foam has been found to serve the purpose well. In the proposed test, test parameters will be sensitivity, background noise, signal fidelity (harmonic distortion), and temporal stability. The design and results of the compact system, based upon laboratory and field experiments, will be presented.

Signal detection in power-law noise: effect of spectrum exponents.

PubMed

Burgess, Arthur E; Judy, Philip F

2007-12-01

Many natural backgrounds have approximately isotropic power spectra of the power-law form, P(f)=K/f(beta), where f is radial frequency. For natural scenes and mammograms, the values of the exponent, beta, range from 1.5 to 3.5. The ideal observer model predicts that for signals with certain properties and backgrounds that can be treated as random noise, a plot of log (contrast threshold) versus log (signal size) will be linear with slope, m, given by: m=(beta-2)/2. This plot is referred to as a contrast-detail (CD) diagram. It is interesting that this predicts a detection threshold that is independent of signal size for beta equal to 2. We present two-alternative forced-choice (2AFC) detection results for human and channelized model observers of a simple signal in filtered noise with exponents from 1.5 to 3.5. The CD diagram results are in good agreement with the prediction of this equation.

Obtaining phase velocity of turbulent boundary layer pressure fluctuations at high subsonic Mach number from wind tunnel data affected by strong background noise

NASA Astrophysics Data System (ADS)

Haxter, Stefan; Brouwer, Jens; Sesterhenn, Jörn; Spehr, Carsten

2017-08-01

Boundary layer measurements at high subsonic Mach number are evaluated in order to obtain the dominant phase velocities of boundary layer pressure fluctuations. The measurements were performed in a transonic wind tunnel which had a very strong background noise. The phase velocity was taken from phase inclination and from the convective peak in one- and two-dimensional wavenumber spectra. An approach was introduced to remove the acoustic noise from the data by applying a method based on CLEAN-SC on the two-dimensional spectra, thereby increasing the frequency range where information about the boundary layer was retrievable. A comparison with prediction models showed some discrepancies in the low-frequency range. Therefore, pressure data from a DNS calculation was used to substantiate the results of the analysis in this frequency range. Using the measured data, the DNS results and a review of the models used for comparison it was found that the phase velocity decreases at low frequencies.

Rejection of randomly coinciding 2ν2β events in ZnMoO4 scintillating bolometers

NASA Astrophysics Data System (ADS)

Chernyak, D. M.; Danevich, F. A.; Giuliani, A.; Mancuso, M.; Nones, C.; Olivieri, E.; Tenconi, M.; Tretyak, V. I.

2014-01-01

Random coincidence of 2ν2β decay events could be one of the main sources of background for 0ν2β decay in cryogenic bolometers due to their poor time resolution. Pulse-shape discrimination by using front edge analysis, the mean-time and χ2 methods was applied to discriminate randomly coinciding 2ν2β events in ZnMoO4 cryogenic scintillating bolometers. The background can be effectively rejected on the level of 99% by the mean-time analysis of heat signals with the rise time about 14 ms and the signal-to-noise ratio 900, and on the level of 98% for the light signals with 3 ms rise time and signal-to-noise ratio of 30 (under a requirement to detect 95% of single events). Importance of the signal-to-noise ratio, correct finding of the signal start and choice of an appropriate sampling frequency are discussed.

Measurement and subtraction of Schumann resonances at gravitational-wave interferometers

NASA Astrophysics Data System (ADS)

Coughlin, Michael W.; Cirone, Alessio; Meyers, Patrick; Atsuta, Sho; Boschi, Valerio; Chincarini, Andrea; Christensen, Nelson L.; De Rosa, Rosario; Effler, Anamaria; Fiori, Irene; Gołkowski, Mark; Guidry, Melissa; Harms, Jan; Hayama, Kazuhiro; Kataoka, Yuu; Kubisz, Jerzy; Kulak, Andrzej; Laxen, Michael; Matas, Andrew; Mlynarczyk, Janusz; Ogawa, Tsutomu; Paoletti, Federico; Salvador, Jacobo; Schofield, Robert; Somiya, Kentaro; Thrane, Eric

2018-05-01

Correlated magnetic noise from Schumann resonances threatens to contaminate the observation of a stochastic gravitational-wave background in interferometric detectors. In previous work, we reported on the first effort to eliminate global correlated noise from the Schumann resonances using Wiener filtering, demonstrating as much as a factor of two reduction in the coherence between magnetometers on different continents. In this work, we present results from dedicated magnetometer measurements at the Virgo and KAGRA sites, which are the first results for subtraction using data from gravitational-wave detector sites. We compare these measurements to a growing network of permanent magnetometer stations, including at the LIGO sites. We show the effect of mutual magnetometer attraction, arguing that magnetometers should be placed at least one meter from one another. In addition, for the first time, we show how dedicated measurements by magnetometers near to the interferometers can reduce coherence to a level consistent with uncorrelated noise, making a potential detection of a stochastic gravitational-wave background possible.

New developments in transit noise and vibration criteria

NASA Astrophysics Data System (ADS)

Hanson, Carl E.

2004-05-01

Federal Transit Administration (FTA) noise and vibration impact criteria were developed in the early 1990's. Noise criteria are ambient-based, developed from the Schultz curve and fundamental research performed by the U.S. Environmental Protection Agency in the 1970's. Vibration criteria are single-value rms vibration velocity levels. After 10 years of experience applying the criteria in assessments of new transit projects throughout the United States, FTA is updating its methods. Approach to assessment of new projects in existing high-noise environments will be clarified. Method for assessing noise impacts due to horn blowing at grade crossings will be provided. Vibration criteria will be expanded to include spectral information. This paper summarizes the background of the current criteria, discusses examples where existing methods are lacking, and describes the planned remedies to improve criteria and methods.

Effects of background noise on recording of portable transient-evoked otoacoustic emission in newborn hearing screening.

PubMed

Salina, Husain; Abdullah, Asma; Mukari, Siti Zamratol Mai-sarah; Azmi, Mohd Tamil

2010-04-01

Transient-evoked otoacoustic emission (TEOAE) is a well-established screening tool for universal newborn hearing screening. The aims of this study are to measure the effects of background noise on recording of TEOAE and the duration required to complete the test at various noise levels. This study is a prospective study from June 2006 until May 2007. The study population were newborns from postnatal wards who were delivered at term pregnancy. Newborns who were more than 8-h old and passed a hearing screening testing using screening auditory brainstem response (SABRe) were further tested with TEOAE in four different test environments [isolation room in the ward during non-peak hour (E1), isolation room in the ward during peak hour (E2), maternal bedside in the ward during non-peak hour (E3) and maternal bedside in the ward during peak hour (E4)]. This study showed that test environment significantly influenced the time required to complete testing in both ears with F [534.23] = 0.945; P < 0.001 on the right ear and F [636.54] = 0.954; P < 0.001 on the left. Our study revealed that TEOAE testing was efficient in defining the presence of normal hearing in our postnatal wards at maternal bedside during non-peak hour with a specificity of 96.8%. Our study concludes that background noise levels for acceptable and accurate TEOAE recording in newborns should not exceed 65 dB A. In addition, when using TEOAE assessment in noisy environments, the time taken to obtain accurate results will greatly increase.

A critical review of hearing-aid single-microphone noise-reduction studies in adults and children.

PubMed

Chong, Foong Yen; Jenstad, Lorienne M

2017-10-26

Single-microphone noise reduction (SMNR) is implemented in hearing aids to suppress background noise. The purpose of this article was to provide a critical review of peer-reviewed studies in adults and children with sensorineural hearing loss who were fitted with hearing aids incorporating SMNR. Articles published between 2000 and 2016 were searched in PUBMED and EBSCO databases. Thirty-two articles were included in the final review. Most studies with adult participants showed that SMNR has no effect on speech intelligibility. Positive results were reported for acceptance of background noise, preference, and listening effort. Studies of school-aged children were consistent with the findings of adult studies. No study with infants or young children of under 5 years old was found. Recent studies on noise-reduction systems not yet available in wearable hearing aids have documented benefits of noise reduction on memory for speech processing for older adults. This evidence supports the use of SMNR for adults and school-aged children when the aim is to improve listening comfort or reduce listening effort. Future research should test SMNR with infants and children who are younger than 5 years of age. Further development, testing, and clinical trials should be carried out on algorithms not yet available in wearable hearing aids. Testing higher cognitive level for speech processing and learning of novel sounds or words could show benefits of advanced signal processing features. These approaches should be expanded to other populations such as children and younger adults. Implications for rehabilitation The review provides a quick reference for students and clinicians regarding the efficacy and effectiveness of SMNR in wearable hearing aids. This information is useful during counseling session to build a realistic expectation among hearing aid users. Most studies in the adult population suggest that SMNR may provide some benefits to adult listeners in terms of listening comfort, acceptance of background noise, and release of cognitive load in a complex listening condition. However, it does not improve speech intelligibility. Studies that examined SMNR in the paediatric population suggest that SMNR may benefit older school-aged children, aged between 10 and 12 years old. The evidence supports the use of SMNR for adults and school-aged children when the aim is to improve listening comfort or reduce listening effort.

Review of weapon noise measurement and damage risk criteria: considerations for auditory protection and performance.

PubMed

Nakashima, Ann; Farinaccio, Rocco

2015-04-01

Noise-induced hearing loss resulting from weapon noise exposure has been studied for decades. A summary of recent work in weapon noise signal analysis, current knowledge of hearing damage risk criteria, and auditory performance in impulse noise is presented. Most of the currently used damage risk criteria are based on data that cannot be replicated or verified. There is a need to address the effects of combined noise exposures, from similar or different weapons and continuous background noise, in future noise exposure regulations. Advancements in hearing protection technology have expanded the options available to soldiers. Individual selection of hearing protection devices that are best suited to the type of exposure, the auditory task requirements, and hearing status of the user could help to facilitate their use. However, hearing protection devices affect auditory performance, which in turn affects situational awareness in the field. This includes communication capability and the localization and identification of threats. Laboratory training using high-fidelity weapon noise recordings has the potential to improve the auditory performance of soldiers in the field, providing a low-cost tool to enhance readiness for combat. Reprint & Copyright © 2015 Association of Military Surgeons of the U.S.

Noise exposure and children's blood pressure and heart rate: the RANCH project

PubMed Central

van Kempen, E; Van Kamp, I; Fischer, P; Davies, H; Houthuijs, D; Stellato, R; Clark, C; Stansfeld, S

2006-01-01

Background Conclusions that can be drawn from earlier studies on noise and children's blood pressure are limited due to inconsistent results, methodological problems, and the focus on school noise exposure. Objectives To investigate the effects of aircraft and road traffic noise exposure on children's blood pressure and heart rate. Methods Participants were 1283 children (age 9–11 years) attending 62 primary schools around two European airports. Data were pooled and analysed using multilevel modelling. Adjustments were made for a range of socioeconomic and lifestyle factors. Results After pooling the data, aircraft noise exposure at school was related to a statistically non‐significant increase in blood pressure and heart rate. Aircraft noise exposure at home was related to a statistically significant increase in blood pressure. Aircraft noise exposure during the night at home was positively and significantly associated with blood pressure. The findings differed between the Dutch and British samples. Negative associations were found between road traffic noise exposure and blood pressure, which cannot be explained. Conclusion On the basis of this study and previous scientific literature, no unequivocal conclusions can be drawn about the relationship between community noise and children's blood pressure. PMID:16728500

Musical Experience and the Aging Auditory System: Implications for Cognitive Abilities and Hearing Speech in Noise

PubMed Central

Parbery-Clark, Alexandra; Strait, Dana L.; Anderson, Samira; Hittner, Emily; Kraus, Nina

2011-01-01

Much of our daily communication occurs in the presence of background noise, compromising our ability to hear. While understanding speech in noise is a challenge for everyone, it becomes increasingly difficult as we age. Although aging is generally accompanied by hearing loss, this perceptual decline cannot fully account for the difficulties experienced by older adults for hearing in noise. Decreased cognitive skills concurrent with reduced perceptual acuity are thought to contribute to the difficulty older adults experience understanding speech in noise. Given that musical experience positively impacts speech perception in noise in young adults (ages 18–30), we asked whether musical experience benefits an older cohort of musicians (ages 45–65), potentially offsetting the age-related decline in speech-in-noise perceptual abilities and associated cognitive function (i.e., working memory). Consistent with performance in young adults, older musicians demonstrated enhanced speech-in-noise perception relative to nonmusicians along with greater auditory, but not visual, working memory capacity. By demonstrating that speech-in-noise perception and related cognitive function are enhanced in older musicians, our results imply that musical training may reduce the impact of age-related auditory decline. PMID:21589653