Science.gov

Sample records for binaural signal detection

  1. The influence of interaural stimulus uncertainty on binaural signal detection.

    PubMed

    Breebaart, J; Kohlrausch, A

    2001-01-01

    This paper investigated the influence of stimulus uncertainty in binaural detection experiments and the predictions of several binaural models for such conditions. Masked thresholds of a 500-Hz sinusoid were measured in an NrhoSpi condition for both running and frozen-noise maskers using a three interval, forced-choice (3IFC) procedure. The nominal masker correlation varied between 0.64 and 1, and the bandwidth of the masker was either 10, 100, or 1,000 Hz. The running-noise thresholds were expected to be higher than the frozen-noise thresholds because of stimulus uncertainty in the running-noise conditions. For an interaural correlation close to +1, no difference between frozen-noise and running-noise thresholds was expected for all values of the masker bandwidth. These expectations were supported by the experimental data: for interaural correlations less than 1.0, substantial differences between frozen and running-noise conditions were observed for bandwidths of 10 and 100 Hz. Two additional conditions were tested to further investigate the influence of stimulus uncertainty. In the first condition a different masker sample was chosen on each trial, but the correlation of the masker was forced to a fixed value. In the second condition one of two independent frozen-noise maskers was randomly chosen on each trial. Results from these experiments emphasized the influence of stimulus uncertainty in binaural detection tasks: if the degree of uncertainty in binaural cues was reduced, thresholds decreased towards thresholds in the conditions without any stimulus uncertainty. In the analysis of the data, stimulus uncertainty was expressed in terms of three theories of binaural processing: the interaural correlation, the EC theory, and a model based on the processing of interaural intensity differences (IIDs) and interaural time differences (ITDs). This analysis revealed that none of the theories tested could quantitatively account for the observed thresholds. In addition

  2. Leak detection utilizing analog binaural (VLSI) techniques

    NASA Astrophysics Data System (ADS)

    Hartley, Frank T.

    1993-08-01

    A detection method and system utilizing silicon models of the traveling wave structure of the human cochlea to spatially and temporally locate a specific sound source in the presence of high noise pandemonium is presented. The detection system combines two-dimensional stereausis representations, which are output by at least three VLSI binaural hearing chips, to generate a three-dimensional stereausis representation including both binaural and spectral information which is then used to locate the sound source.

  3. Leak detection utilizing analog binaural (VLSI) techniques

    NASA Astrophysics Data System (ADS)

    Hartley, Frank T.

    1995-06-01

    A detection method and system utilizing silicon models of the traveling wave structure of the human cochlea to spatially and temporally locate a specific sound source in the presence of high noise pandemonium. The detection system combines two-dimensional stereausis representations, which are output by at least three VLSI binaural hearing chips, to generate a three-dimensional stereausis representation including both binaural and spectral information which is then used to locate the sound source.

  4. Analog Binaural Circuits for Detecting and Locating Leaks

    NASA Technical Reports Server (NTRS)

    Hartley, Frank T.

    2003-01-01

    Very-large-scale integrated (VLSI) analog binaural signal-processing circuits have been proposed for use in detecting and locating leaks that emit noise in the ultrasonic frequency range. These circuits would be designed to function even in the presence of intense lower-frequency background noise that could include sounds associated with flow and pumping. Each of the proposed circuits would include the approximate electronic equivalent of a right and a left cochlea plus correlator circuits. A pair of transducers (microphones or accelerometers), corresponding to right and left ears, would provide the inputs to their respective cochleas from different locations (e.g., from different positions along a pipe). The correlation circuits plus some additional external circuits would determine the difference between the times of arrival of a common leak sound at the two transducers. Then the distance along the pipe from either transducer to the leak could be estimated from the time difference and the speed of sound along the pipe. If three or more pairs of transducers and cochlear/correlator circuits were available and could suitably be positioned, it should be possible to locate a leak in three dimensions by use of sound propagating through air.

  5. Subjective diffuseness of music signals convolved with binaural impulse responses

    NASA Astrophysics Data System (ADS)

    Shimokura, Ryota; Tronchin, Lamberto; Cocchi, Alessandro; Soeta, Yoshiharu

    2011-07-01

    The spatial impression of sound in a hall can be quantified using sound field factors such as the interaural cross-correlation coefficient (IACC) calculated from binaural impulse response (BIR), henceforth denoted by IACC IR. The subjective diffuseness for the listener is a spatial attribute which depends on factors associated both with the source signal and with the actual sound field, and is quantified using the IACC of the signal received by the listener, henceforth denoted by IACC SR. Therefore, the subjective diffuseness in a given hall may change with the music. The aims of this study are to estimate the IACC SR from the IACC IR and the factors, which is obtained from autocorrelation function (ACF) of music signal, and to evaluate the subjective diffuseness by these factors. First, the relationship between the IACC IR and IACC SR was investigated. Second, subjective diffuseness was measured by a psycho-acoustical experiment. As a result, the IACC SR could be estimated from the IACC IR of the BIR and the effective duration ( τe) from the ACF of music signal. It was found that the effects of BIRs on subjective diffuseness could be evaluated by IACC IR for almost all subjects, while the effects of music signals could be evaluated by the τe and the width of the peak at τ=0 ( Wϕ(0) ) of the ACF.

  6. 4D time-frequency representation for binaural speech signal processing

    NASA Astrophysics Data System (ADS)

    Mikhael, Raed; Szu, Harold H.

    2006-04-01

    Hearing is the ability to detect and process auditory information produced by the vibrating hair cilia residing in the corti of the ears to the auditory cortex of the brain via the auditory nerve. The primary and secondary corti of the brain interact with one another to distinguish and correlate the received information by distinguishing the varying spectrum of arriving frequencies. Binaural hearing is nature's way of employing the power inherent in working in pairs to process information, enhance sound perception, and reduce undesired noise. One ear might play a prominent role in sound recognition, while the other reinforces their perceived mutual information. Developing binaural hearing aid devices can be crucial in emulating the working powers of two ears and may be a step closer to significantly alleviating hearing loss of the inner ear. This can be accomplished by combining current speech research to already existing technologies such as RF communication between PDAs and Bluetooth. Ear Level Instrument (ELI) developed by Micro-tech Hearing Instruments and Starkey Laboratories is a good example of a digital bi-directional signal communicating between a PDA/mobile phone and Bluetooth. The agreement and disagreement of arriving auditory information to the Bluetooth device can be classified as sound and noise, respectively. Finding common features of arriving sound using a four coordinate system for sound analysis (four dimensional time-frequency representation), noise can be greatly reduced and hearing aids would become more efficient. Techniques developed by Szu within an Artificial Neural Network (ANN), Blind Source Separation (BSS), Adaptive Wavelets Transform (AWT), and Independent Component Analysis (ICA) hold many possibilities to the improvement of acoustic segmentation of phoneme, all of which will be discussed in this paper. Transmitted and perceived acoustic speech signal will improve, as the binaural hearing aid will emulate two ears in sound

  7. Similar Impacts of the Interaural Delay and Interaural Correlation on Binaural Gap Detection

    PubMed Central

    Kong, Lingzhi; Xie, Zilong; Lu, Lingxi; Qu, Tianshu; Wu, Xihong; Yan, Jun; Li, Liang

    2015-01-01

    The subjective representation of the sounds delivered to the two ears of a human listener is closely associated with the interaural delay and correlation of these two-ear sounds. When the two-ear sounds, e.g., arbitrary noises, arrive simultaneously, the single auditory image of the binaurally identical noises becomes increasingly diffuse, and eventually separates into two auditory images as the interaural correlation decreases. When the interaural delay increases from zero to several milliseconds, the auditory image of the binaurally identical noises also changes from a single image to two distinct images. However, measuring the effect of these two factors on an identical group of participants has not been investigated. This study examined the impacts of interaural correlation and delay on detecting a binaurally uncorrelated fragment (interaural correlation = 0) embedded in the binaurally correlated noises (i.e., binaural gap or break in interaural correlation). We found that the minimum duration of the binaural gap for its detection (i.e., duration threshold) increased exponentially as the interaural delay between the binaurally identical noises increased linearly from 0 to 8 ms. When no interaural delay was introduced, the duration threshold also increased exponentially as the interaural correlation of the binaurally correlated noises decreased linearly from 1 to 0.4. A linear relationship between the effect of interaural delay and that of interaural correlation was described for listeners participating in this study: a 1 ms increase in interaural delay appeared to correspond to a 0.07 decrease in interaural correlation specific to raising the duration threshold. Our results imply that a tradeoff may exist between the impacts of interaural correlation and interaural delay on the subjective representation of sounds delivered to two human ears. PMID:26125970

  8. A model that predicts the binaural advantage to speech intelligibility from the mixed target and interferer signals.

    PubMed

    Cosentino, Stefano; Marquardt, Torsten; McAlpine, David; Culling, John F; Falk, Tiago H

    2014-02-01

    A model is presented that predicts the binaural advantage to speech intelligibility by analyzing the right and left recordings at the two ears containing mixed target and interferer signals. This auditory-inspired model implements an equalization-cancellation stage to predict the binaural unmasking (BU) component, in conjunction with a modulation-frequency estimation block to estimate the "better ear" effect (BE) component of the binaural advantage. The model's performance was compared to experimental data obtained under anechoic and reverberant conditions using a single speech-shaped noise interferer paradigm. The internal BU and BE components were compared to those of the speech intelligibility model recently proposed by Lavandier et al. [J. Acoust. Soc. Am. 131, 218-231 (2012)], which requires separate inputs for target and interferer. The data indicate that the proposed model provides comparably good predictions from a mixed-signals input under both anechoic and reverberant conditions.

  9. Binaural detection with narrowband and wideband reproducible noise maskers: II. Results for rabbit

    NASA Astrophysics Data System (ADS)

    Zheng, Ling; Early, Susan J.; Mason, Christine R.; Idrobo, Fabio; Harrison, J. Michael; Carney, Laurel H.

    2002-01-01

    Binaural detection with narrowband and wideband noise maskers was examined by using a Pavlovian-conditioned eyeblink response in rabbits. The target was a tone at 500 Hz, and the maskers were ten individual noise samples having one of two bandwidths, 200 Hz (410 Hz to 610 Hz) or 2900 Hz (100 Hz to 3 kHz). The narrowband noise maskers were created by filtering the wideband noise maskers such that the two sets of maskers had identical spectra in the 200-Hz frequency region surrounding the tone. The responses across the set of noise maskers were compared across bandwidths and across interaural configurations (N0S0 and N0Sπ). Responses across the set of noise waveforms were not strongly correlated across bandwidths; this result is inconsistent with models for binaural detection that depend only upon the narrow band of energy centered at the frequency of the target tone. Responses were correlated across interaural configurations for the wideband masker condition, but not for the narrowband masker. All of these results were consistent with the companion study of human listeners [Evilsizer et al., J. Acoust. Soc. Am. 111, 336-345 (2002)] and with the results of human studies of binaural detection that used only wideband [Gilkey et al., J. Acoust. Soc. Am. 78, 1207-1219 (1985)] or narrowband [Isabelle and Colburn, J. Acoust. Soc. Am. 89, 352-259 (1991)] individual noise maskers.

  10. Application of orthogonal ultrasonic signals and binaural processing for imaging of the environment

    PubMed

    Kazys; Svilainis; Mazeika

    2000-03-01

    Data acquisition rates in ultrasonic imaging systems are limited by the finite value of the speed of ultrasonic waves. In order to improve the imaging speed, it is proposed to perform simultaneous scanning of the environment in different directions. In order to avoid cross-talk between adjacent channels in different directions, different orthogonal signals are transmitted. Application of cross-correlation processing and non-linear iterative deconvolution enables the reliable separation of signals transmitted by different sources and reflected by multiple targets. The spatial positions of the targets are found using the data obtained after the non-linear deconvolution as the initial data for binaural or tri-aural processing. This approach has been exploited in ultrasonic sonar used for navigation of mobile robots.

  11. The Binaural Masking-Level Difference of Mandarin Tone Detection and the Binaural Intelligibility-Level Difference of Mandarin Tone Recognition in the Presence of Speech-Spectrum Noise

    PubMed Central

    Ho, Cheng-Yu; Li, Pei-Chun; Chiang, Yuan-Chuan; Young, Shuenn-Tsong; Chu, Woei-Chyn

    2015-01-01

    Binaural hearing involves using information relating to the differences between the signals that arrive at the two ears, and it can make it easier to detect and recognize signals in a noisy environment. This phenomenon of binaural hearing is quantified in laboratory studies as the binaural masking-level difference (BMLD). Mandarin is one of the most commonly used languages, but there are no publication values of BMLD or BILD based on Mandarin tones. Therefore, this study investigated the BMLD and BILD of Mandarin tones. The BMLDs of Mandarin tone detection were measured based on the detection threshold differences for the four tones of the voiced vowels /i/ (i.e., /i1/, /i2/, /i3/, and /i4/) and /u/ (i.e., /u1/, /u2/, /u3/, and /u4/) in the presence of speech-spectrum noise when presented interaurally in phase (S0N0) and interaurally in antiphase (SπN0). The BILDs of Mandarin tone recognition in speech-spectrum noise were determined as the differences in the target-to-masker ratio (TMR) required for 50% correct tone recognitions between the S0N0 and SπN0 conditions. The detection thresholds for the four tones of /i/ and /u/ differed significantly (p<0.001) between the S0N0 and SπN0 conditions. The average detection thresholds of Mandarin tones were all lower in the SπN0 condition than in the S0N0 condition, and the BMLDs ranged from 7.3 to 11.5 dB. The TMR for 50% correct Mandarin tone recognitions differed significantly (p<0.001) between the S0N0 and SπN0 conditions, at –13.4 and –18.0 dB, respectively, with a mean BILD of 4.6 dB. The study showed that the thresholds of Mandarin tone detection and recognition in the presence of speech-spectrum noise are improved when phase inversion is applied to the target speech. The average BILDs of Mandarin tones are smaller than the average BMLDs of Mandarin tones. PMID:25835987

  12. Binaural Interaction in Specific Language Impairment: An Auditory Evoked Potential Study

    ERIC Educational Resources Information Center

    Clarke, Elaine M; Adams, Catherine

    2007-01-01

    The aim of the study was to examine whether auditory binaural interaction, defined as any difference between binaurally evoked responses and the sum of monaurally evoked responses, which is thought to index functions involved in the localization and detection of signals in background noise, is atypical in a group of children with specific language…

  13. Responses of neurons in the auditory pathway of the barn owl to partially correlated binaural signals.

    PubMed

    Albeck, Y; Konishi, M

    1995-10-01

    1. Extracellular single-unit recording in anesthetized barn owls was used to study neuronal response to dichotic stimuli of variable binaural correlation (BC). Recordings were made in the output fibers of nucleus laminaris (NL), the anterior division of the ventral lateral lemniscal nucleus (VLVa), the core of the central nucleus of the inferior colliculus (ICcC), the lateral shell of the central nucleus of the inferior colliculus (ICcLS), and the external nucleus of the inferior colliculus (ICx). 2. The response of all neurons sensitive to interaural time difference (ITD) varied with BC. The relationship between BC and impulse number fits a linear, a parabolic, or a ramp model. A linear or parabolic model fits most neurons in low-level nuclei. Higher order neurons in ICx did not respond to noise bursts with strong negative binaural correlation, creating a ramp-like response to BC. 3. A neuron's ability to detect ITD varied as a function of BC. Conversely, a neuron's response to BC changed with ITD. Neurons in NL, VLVa, and ICcC show almost periodic ITD response curves. In these neurons peaks and troughs of ITD response curves diminished as BC decreased, creating a flat ITD response when BC = 0. When BC was set to -1, the most favorable ITD became the least favorable one and vice versa. The ITD response curve of ICx neurons usually has a single dominant peak. The response of those neurons to a negatively correlated noise pair (BC = -1) showed two ITD peaks, flanking the position of the primary peak. 4. The parabolic BC response of NL neurons fits the prediction of the cross-correlation model, assuming half-wave rectification of the sound by the cochlea. Linear response is not predicted by the model. However, the parabolic and the linear neurons probably do not belong to two distinct groups as the difference between them is not statistically significant. Thus, the cross-correlation model provides a good description of the binaural response not only in NL but also in

  14. Binaural processing model based on contralateral inhibition. II. Dependence on spectral parameters.

    PubMed

    Breebaart, J; van de Par, S; Kohlrausch, A

    2001-08-01

    This and two accompanying articles [Breebaart et al., J. Acoust. Soc. Am. 110, 1074-1088 (2001); 110, 1105-1117 (2001)] describe a computational model for the signal processing in the binaural auditory system. The model consists of several stages of monaural and binaural preprocessing combined with an optimal detector. In the present article the model is tested and validated by comparing its predictions with experimental data for binaural discrimination and masking conditions as a function of the spectral parameters of both masker and signal. For this purpose, the model is used as an artificial observer in a three-interval, forced-choice adaptive procedure. All model parameters were kept constant for all simulations described in this and the subsequent article. The effects of the following experimental parameters were investigated: center frequency of both masker and target, bandwidth of masker and target, the interaural phase relations of masker and target, and the level of the masker. Several phenomena that occur in binaural listening conditions can be accounted for. These include the wider effective binaural critical bandwidth observed in band-widening NoS(pi) conditions, the different masker-level dependence of binaural detection thresholds for narrow- and for wide-band maskers, the unification of IID and ITD sensitivity with binaural detection data, and the dependence of binaural thresholds on frequency. PMID:11519577

  15. The contribution of static and dynamically varying ITDs and IIDs to binaural detection.

    PubMed

    Breebaart, J; van de Par, S; Kohlrausch, A

    1999-08-01

    This paper investigates the relative contribution of various interaural cues to binaural unmasking in conditions with an interaurally in-phase masker and an out-of-phase signal (MoS pi). By using a modified version of multiplied noise as the masker and a sinusoid as the signal, conditions with only interaural intensity differences (IIDs), only interaural time differences (ITDs), or combinations of the two were realized. In addition, the experimental procedure allowed the presentation of specific combinations of static and dynamically varying interaural differences. In these conditions with multiplied noise as masker, the interaural differences have a bimodal distribution with a minimum at zero IID or ITD. Additionally, by using the sinusoid as masker and the multiplied noise as signal, a unimodal distribution of the interaural differences was realized. Through this variation in the shape of the distributions, the close correspondence between the change in the interaural cross correlation and the size of the interaural differences is no longer found, in contrast to the situation for a Gaussian-noise masker [Domnitz and Colburn, J. Acoust. Soc. Am. 59, 598-601 (1976)]. When analyzing the mean thresholds across subjects, the experimental results could not be predicted from parameters of the distributions of the interaural differences (the mean, the standard deviation, or the root-mean-square value). A better description of the subjects' performance was given by the change in the interaural correlation, but this measure failed in conditions which produced a static interaural intensity difference. The data could best be described by using the energy of the difference signal as the decision variable, an approach similar to that of the equalization and cancellation model. PMID:10462803

  16. Binaural room simulation

    NASA Technical Reports Server (NTRS)

    Lehnert, H.; Blauert, Jens; Pompetzki, W.

    1991-01-01

    In every-day listening the auditory event perceived by a listener is determined not only by the sound signal that a sound emits but also by a variety of environmental parameters. These parameters are the position, orientation and directional characteristics of the sound source, the listener's position and orientation, the geometrical and acoustical properties of surfaces which affect the sound field and the sound propagation properties of the surrounding fluid. A complete set of these parameters can be called an Acoustic Environment. If the auditory event perceived by a listener is manipulated in such a way that the listener is shifted acoustically into a different acoustic environment without moving himself physically, a Virtual Acoustic Environment has been created. Here, we deal with a special technique to set up nearly arbitrary Virtual Acoustic Environments, the Binaural Room Simulation. The purpose of the Binaural Room Simulation is to compute the binaural impulse response related to a virtual acoustic environment taking into account all parameters mentioned above. One possible way to describe a Virtual Acoustic Environment is the concept of the virtual sound sources. Each of the virtual sources emits a certain signal which is correlated but not necessarily identical with the signal emitted by the direct sound source. If source and receiver are non moving, the acoustic environment becomes a linear time-invariant system. Then, the Binaural Impulse Response from the source to a listener' s eardrums contains all relevant auditory information related to the Virtual Acoustic Environment. Listening into the simulated environment can easily be achieved by convolving the Binaural Impulse Response with dry signals and representing the results via headphones.

  17. Amplitude modulation detection by human listeners in reverberant sound fields: Carrier bandwidth effects and binaural versus monaural comparison

    PubMed Central

    Zahorik, Pavel; Kim, Duck O.; Kuwada, Shigeyuki; Anderson, Paul W.; Brandewie, Eugene; Collecchia, Regina; Srinivasan, Nirmal

    2012-01-01

    Previous work [Zahorik et al., POMA, 12, 050005 (2011)] has reported that for a broadband noise carrier signal in a simulated reverberant sound field, human sensitivity to amplitude modulation (AM) is higher than would be predicted based on the broadband acoustical modulation transfer function (MTF) of the listening environment. Interpretation of this result was complicated by the fact that acoustical MTFs of rooms are often quite different for different carrier frequency regions, and listeners may have selectively responded to advantageous carrier frequency regions where the effective acoustic modulation loss due to the room was less than indicated by a broadband acoustic MTF analysis. Here, AM sensitivity testing and acoustic MTF analyses were expanded to include narrowband noise carriers (1-octave and 1/3-octave bands centered at 4 kHz), as well as monaural and binaural listening conditions. Narrowband results were found to be consistent with broadband results: In a reverberant sound field, human AM sensitivity is higher than indicated by the acoustical MTFs. The effect was greatest for modulation frequencies above 32 Hz and was present whether the stimulation was monaural or binaural. These results are suggestive of mechanisms that functionally enhance modulation in reverberant listening. PMID:23437416

  18. Binaural release from masking with single- and multi-electrode stimulation in children with cochlear implants.

    PubMed

    Todd, Ann E; Goupell, Matthew J; Litovsky, Ruth Y

    2016-07-01

    Cochlear implants (CIs) provide children with access to speech information from a young age. Despite bilateral cochlear implantation becoming common, use of spatial cues in free field is smaller than in normal-hearing children. Clinically fit CIs are not synchronized across the ears; thus binaural experiments must utilize research processors that can control binaural cues with precision. Research to date has used single pairs of electrodes, which is insufficient for representing speech. Little is known about how children with bilateral CIs process binaural information with multi-electrode stimulation. Toward the goal of improving binaural unmasking of speech, this study evaluated binaural unmasking with multi- and single-electrode stimulation. Results showed that performance with multi-electrode stimulation was similar to the best performance with single-electrode stimulation. This was similar to the pattern of performance shown by normal-hearing adults when presented an acoustic CI simulation. Diotic and dichotic signal detection thresholds of the children with CIs were similar to those of normal-hearing children listening to a CI simulation. The magnitude of binaural unmasking was not related to whether the children with CIs had good interaural time difference sensitivity. Results support the potential for benefits from binaural hearing and speech unmasking in children with bilateral CIs. PMID:27475132

  19. Binaural processing model based on contralateral inhibition. I. Model structure.

    PubMed

    Breebaart, J; van de Par, S; Kohlrausch, A

    2001-08-01

    This article presents a quantitative binaural signal detection model which extends the monaural model described by Dau et al. [J. Acoust. Soc. Am. 99, 3615-3622 (1996)]. The model is divided into three stages. The first stage comprises peripheral preprocessing in the right and left monaural channels. The second stage is a binaural processor which produces a time-dependent internal representation of the binaurally presented stimuli. This stage is based on the Jeffress delay line extended with tapped attenuator lines. Through this extension, the internal representation codes both interaural time and intensity differences. In contrast to most present-day models, which are based on excitatory-excitatory interaction, the binaural interaction in the present model is based on contralateral inhibition of ipsilateral signals. The last stage, a central processor, extracts a decision variable that can be used to detect the presence of a signal in a detection task, but could also derive information about the position and the compactness of a sound source. In two accompanying articles, the model predictions are compared with data obtained with human observers in a great variety of experimental conditions. PMID:11519576

  20. Binaural comodulation masking release: Effects of masker interaural correlation

    PubMed Central

    Hall, Joseph W.; Buss, Emily; Grose, John H.

    2007-01-01

    Binaural detection was examined for a signal presented in a narrow band of noise centered on the on-signal masking band (OSB) or in the presence of flanking noise bands that were random or comodulated with respect to the OSB. The noise had an interaural correlation of 1.0 (No), 0.99 or 0.95. In No noise, random flanking bands worsened Sπ detection and comodulated bands improved Sπ detection for some listeners but had no effect for other listeners. For the 0.99 or 0.95 interaural correlation conditions, random flanking bands were less detrimental to Sπ detection and comodulated flanking bands improved Sπ detection for all listeners. Analyses based on signal detection theory indicated that the improvement in Sπ thresholds obtained with comodulated bands was not compatible with an optimal combination of monaural and binaural cues or to across-frequency analyses of dynamic interaural phase differences. Two accounts consistent with the improvement in Sπ thresholds in comodulated noise were (1) envelope information carried by the flanking bands improves the weighting of binaural cues associated with the signal; (2) the auditory system is sensitive to across-frequency differences in ongoing interaural correlation. PMID:17225415

  1. Binaural comodulation masking release: effects of masker interaural correlation.

    PubMed

    Hall, Joseph W; Buss, Emily; Grose, John H

    2006-12-01

    Binaural detection was examined for a signal presented in a narrow band of noise centered on the on-signal masking band (OSB) or in the presence of flanking noise bands that were random or comodulated with respect to the OSB. The noise had an interaural correlation of 1.0 (No), 0.99 or 0.95. In No noise, random flanking bands worsened Spi detection and comodulated bands improved Spi detection for some listeners but had no effect for other listeners. For the 0.99 or 0.95 interaural correlation conditions, random flanking bands were less detrimental to Spi detection and comodulated flanking bands improved Spi detection for all listeners. Analyses based on signal detection theory indicated that the improvement in Spi thresholds obtained with comodulated bands was not compatible with an optimal combination of monaural and binaural cues or to across-frequency analyses of dynamic interaural phase differences. Two accounts consistent with the improvement in Spi thresholds in comodulated noise were (1) envelope information carried by the flanking bands improves the weighting of binaural cues associated with the signal; (2) the auditory system is sensitive to across-frequency differences in ongoing interaural correlation.

  2. Binaural Rendering in MPEG Surround

    NASA Astrophysics Data System (ADS)

    Breebaart, Jeroen; Villemoes, Lars; Kjörling, Kristofer

    2008-12-01

    This paper describes novel methods for evoking a multichannel audio experience over stereo headphones. In contrast to the conventional convolution-based approach where, for example, five input channels are filtered using ten head-related transfer functions, the current approach is based on a parametric representation of the multichannel signal, along with either a parametric representation of the head-related transfer functions or a reduced set of head-related transfer functions. An audio scene with multiple virtual sound sources is represented by a mono or a stereo downmix signal of all sound source signals, accompanied by certain statistical (spatial) properties. These statistical properties of the sound sources are either combined with statistical properties of head-related transfer functions to estimate "binaural parameters" that represent the perceptually relevant aspects of the auditory scene or used to create a limited set of combined head-related transfer functions that can be applied directly on the downmix signal. Subsequently, a binaural rendering stage reinstates the statistical properties of the sound sources by applying the estimated binaural parameters or the reduced set of combined head-related transfer functions directly on the downmix. If combined with parametric multichannel audio coders such as MPEG Surround, the proposed methods are advantageous over conventional methods in terms of perceived quality and computational complexity.

  3. Comparing Binaural Pre-processing Strategies II

    PubMed Central

    Hu, Hongmei; Krawczyk-Becker, Martin; Marquardt, Daniel; Herzke, Tobias; Coleman, Graham; Adiloğlu, Kamil; Bomke, Katrin; Plotz, Karsten; Gerkmann, Timo; Doclo, Simon; Kollmeier, Birger; Hohmann, Volker; Dietz, Mathias

    2015-01-01

    Several binaural audio signal enhancement algorithms were evaluated with respect to their potential to improve speech intelligibility in noise for users of bilateral cochlear implants (CIs). 50% speech reception thresholds (SRT50) were assessed using an adaptive procedure in three distinct, realistic noise scenarios. All scenarios were highly nonstationary, complex, and included a significant amount of reverberation. Other aspects, such as the perfectly frontal target position, were idealized laboratory settings, allowing the algorithms to perform better than in corresponding real-world conditions. Eight bilaterally implanted CI users, wearing devices from three manufacturers, participated in the study. In all noise conditions, a substantial improvement in SRT50 compared to the unprocessed signal was observed for most of the algorithms tested, with the largest improvements generally provided by binaural minimum variance distortionless response (MVDR) beamforming algorithms. The largest overall improvement in speech intelligibility was achieved by an adaptive binaural MVDR in a spatially separated, single competing talker noise scenario. A no-pre-processing condition and adaptive differential microphones without a binaural link served as the two baseline conditions. SRT50 improvements provided by the binaural MVDR beamformers surpassed the performance of the adaptive differential microphones in most cases. Speech intelligibility improvements predicted by instrumental measures were shown to account for some but not all aspects of the perceptually obtained SRT50 improvements measured in bilaterally implanted CI users. PMID:26721921

  4. Binaural Loudness Constancy.

    PubMed

    Culling, John F; Dare, Helen

    2016-01-01

    In binaural loudness summation, diotic presentation of a sound usually produces greater loudness than monaural presentation. However, experiments using loudspeaker presentation with and without earplugs find that magnitude estimates of loudness are little altered by the earplug, suggesting a form of loudness constancy. We explored the significance of controlling stimulation of the second ear using meatal occlusion as opposed to the deactivation of one earphone. We measured the point of subjective loudness equality (PSLE) for monaural vs. binaural presentation using an adaptive technique for both speech and noise. These stimuli were presented in a reverberant room over a loudspeaker to the right of the listener, or over lightweight headphones. Using the headphones, stimuli were either presented dry, or matched to those of the loudspeaker by convolution with impulse responses measured from the loudspeaker to the listener position, using an acoustic manikin. The headphone response was also compensated. Using the loudspeaker, monaural presentation was achieved by instructing the listener to block the left ear with a finger. Near perfect binaural loudness constancy was observed using loudspeaker presentation, while there was a summation effect of 3-6 dB for both headphone conditions. However, only partial constancy was observed when meatal occlusion was simulated. These results suggest that there may be contributions to binaural loudness constancy from residual low frequencies at the occluded ear as well as a cognitive element, which is activated by the knowledge that one ear is occluded.

  5. Delayed Detection of Tonal Targets in Background Noise in Dyslexia

    ERIC Educational Resources Information Center

    Chait, Maria; Eden, Guinevere; Poeppel, David; Simon, Jonathan Z.; Hill, Deborah F.; Flowers, D. Lynn

    2007-01-01

    Individuals with developmental dyslexia are often impaired in their ability to process certain linguistic and even basic non-linguistic auditory signals. Recent investigations report conflicting findings regarding impaired low-level binaural detection mechanisms associated with dyslexia. Binaural impairment has been hypothesized to stem from a…

  6. The neural substrate for binaural masking level differences in the auditory cortex.

    PubMed

    Gilbert, Heather J; Shackleton, Trevor M; Krumbholz, Katrin; Palmer, Alan R

    2015-01-01

    The binaural masking level difference (BMLD) is a phenomenon whereby a signal that is identical at each ear (S0), masked by a noise that is identical at each ear (N0), can be made 12-15 dB more detectable by inverting the waveform of either the tone or noise at one ear (Sπ, Nπ). Single-cell responses to BMLD stimuli were measured in the primary auditory cortex of urethane-anesthetized guinea pigs. Firing rate was measured as a function of signal level of a 500 Hz pure tone masked by low-passed white noise. Responses were similar to those reported in the inferior colliculus. At low signal levels, the response was dominated by the masker. At higher signal levels, firing rate either increased or decreased. Detection thresholds for each neuron were determined using signal detection theory. Few neurons yielded measurable detection thresholds for all stimulus conditions, with a wide range in thresholds. However, across the entire population, the lowest thresholds were consistent with human psychophysical BMLDs. As in the inferior colliculus, the shape of the firing-rate versus signal-level functions depended on the neurons' selectivity for interaural time difference. Our results suggest that, in cortex, BMLD signals are detected from increases or decreases in the firing rate, consistent with predictions of cross-correlation models of binaural processing and that the psychophysical detection threshold is based on the lowest neural thresholds across the population.

  7. Loudness enhancement - Monaural, binaural, and dichotic

    NASA Technical Reports Server (NTRS)

    Elmasian, R.; Galambos, R.

    1975-01-01

    When one tone burst (T) precedes another (S) by 100 msec, variations in the intensity of T systematically influence the loudness of S. When T is more intense than S, S is increased; and when T is less intense, S loudness is decreased. This occurs in monaural, binaural, and dichotic paradigms of signal presentation. When T and S are presented to the same ear (monaural or binaural), there is more enhancement with less intersubject variability than when they are presented to different ears (dichotic paradigm). Monaural enhancements as large as 30 dB can readily be demonstrated, but decrements rarely exceed 5 dB. Possible physiological mechanisms are discussed for this loudness enhancement, which apparently shares certain characteristics with time-order error, assimilation, and temporal partial masking experiments.

  8. Impact of monaural frequency compression on binaural fusion at the brainstem level.

    PubMed

    Klauke, Isabelle; Kohl, Manuel C; Hannemann, Ronny; Kornagel, Ulrich; Strauss, Daniel J; Corona-Strauss, Farah I

    2015-08-01

    A classical objective measure for binaural fusion at the brainstem level is the so-called β-wave of the binaural interaction component (BIC) in the auditory brainstem response (ABR). However, in some cases it appeared that a reliable detection of this component still remains a challenge. In this study, we investigate the wavelet phase synchronization stability (WPSS) of ABR data for the analysis of binaural fusion and compare it to the BIC. In particular, we examine the impact of monaural nonlinear frequency compression on binaural fusion. As the auditory system is tonotopically organized, an interaural frequency mismatch caused by monaural frequency compression could negatively effect binaural fusion. In this study, only few subjects showed a detectable β-wave and in most cases only for low ITDs. However, we present a novel objective measure for binaural fusion that outperforms the current state-of-the-art technique (BIC): the WPSS analysis showed a significant difference between the phase stability of the sum of the monaurally evoked responses and the phase stability of the binaurally evoked ABR. This difference could be an indicator for binaural fusion in the brainstem. Furthermore, we observed that monaural frequency compression could indeed effect binaural fusion, as the WPSS results for this condition vary strongly from the results obtained without frequency compression.

  9. Effects of binaural decorrelation on neural and behavioral processing of interaural level differences in the barn owl (Tyto alba).

    PubMed

    Egnor, S E

    2001-10-01

    The effect of binaural decorrelation on the processing of interaural level difference cues in the barn owl (Tyto alba) was examined behaviorally and electrophysiologically. The electrophysiology experiment measured the effect of variations in binaural correlation on the first stage of interaural level difference encoding in the central nervous system. The responses of single neurons in the posterior part of the ventral nucleus of the lateral lemniscus were recorded to stimulation with binaurally correlated and binaurally uncorrelated noise. No significant differences in interaural level difference sensitivity were found between conditions. Neurons in the posterior part of the ventral nucleus of the lateral lemniscus encode the interaural level difference of binaurally correlated and binaurally uncorrelated noise with equal accuracy and precision. This nucleus therefore supplies higher auditory centers with an undegraded interaural level difference signal for sound stimuli that lack a coherent interaural time difference. The behavioral experiment measured auditory saccades in response to interaural level differences presented in binaurally correlated and binaurally uncorrelated noise. The precision and accuracy of sound localization based on interaural level difference was reduced but not eliminated for binaurally uncorrelated signals. The observation that barn owls continue to vary auditory saccades with the interaural level difference of binaurally uncorrelated stimuli suggests that neurons that drive head saccades can be activated by incomplete auditory spatial information. PMID:11763957

  10. Walsh transforms and signal detection

    NASA Technical Reports Server (NTRS)

    Welch, L. R.

    1977-01-01

    The detection of signals using Walsh power spectral estimates is analyzed. In addition, a generalization of this method of estimation is evaluated. The conclusion is that Walsh transforms are not suitable tools for the detection of weak signals in noise.

  11. Binaural detection with narrowband and wideband reproducible noise maskers. IV. Models using interaural time, level, and envelope differences

    PubMed Central

    Mao, Junwen; Carney, Laurel H.

    2014-01-01

    The addition of out-of-phase tones to in-phase noises results in dynamic interaural level difference (ILD) and interaural time difference (ITD) cues for the dichotic tone-in-noise detection task. Several models have been used to predict listeners' detection performance based on ILD, ITD, or different combinations of the two cues. The models can be tested using detection performance from an ensemble of reproducible-noise maskers. Previous models cannot predict listeners' detection performance for reproducible-noise maskers without fitting the data. Here, two models were tested for narrowband and wideband reproducible-noise experiments. One model was a linear combination of ILD and ITD that included the generally ignored correlation between the two cues. The other model was based on a newly proposed cue, the slope of the interaural envelope difference (SIED). Predictions from both models explained a significant portion of listeners' performance for detection of a 500-Hz tone in wideband noise. Predictions based on the SIED approached the predictable variance in the wideband condition. The SIED represented a nonlinear combination of ILD and ITD, with the latter cue dominating. Listeners did not use a common strategy (cue) to detect tones in the narrowband condition and may use different single frequencies or different combinations of frequency channels. PMID:25234891

  12. Combination of Adaptive Feedback Cancellation and Binaural Adaptive Filtering in Hearing Aids

    NASA Astrophysics Data System (ADS)

    Lombard, Anthony; Reindl, Klaus; Kellermann, Walter

    2009-12-01

    We study a system combining adaptive feedback cancellation and adaptive filtering connecting inputs from both ears for signal enhancement in hearing aids. For the first time, such a binaural system is analyzed in terms of system stability, convergence of the algorithms, and possible interaction effects. As major outcomes of this study, a new stability condition adapted to the considered binaural scenario is presented, some already existing and commonly used feedback cancellation performance measures for the unilateral case are adapted to the binaural case, and possible interaction effects between the algorithms are identified. For illustration purposes, a blind source separation algorithm has been chosen as an example for adaptive binaural spatial filtering. Experimental results for binaural hearing aids confirm the theoretical findings and the validity of the new measures.

  13. Unilateral spectral and temporal compression reduces binaural fusion for normal hearing listeners with cochlear implant simulations.

    PubMed

    Aronoff, Justin M; Shayman, Corey; Prasad, Akila; Suneel, Deepa; Stelmach, Julia

    2015-02-01

    Patients with single sided deafness have recently begun receiving cochlear implants in their deaf ear. These patients gain a significant benefit from having a cochlear implant. However, despite this benefit, they are considerably slower to develop binaural abilities such as summation compared to bilateral cochlear implant patients. This suggests that these patients have difficulty fusing electric and acoustic signals. Although this may reflect inherent differences between electric and acoustic stimulation, it may also reflect properties of the processor and fitting system, which result in spectral and temporal compression. To examine the possibility that unilateral spectral and temporal compression can adversely affect binaural fusion, this study tested normal hearing listeners' binaural fusion through the use of vocoded speech with unilateral spectral and temporal compression. The results indicate that unilateral spectral and temporal compression can each hinder binaural fusion and thus may adversely affect binaural abilities in patients with single sided deafness who use a cochlear implant in their deaf ear. PMID:25549574

  14. Comparing Binaural Pre-processing Strategies III

    PubMed Central

    Warzybok, Anna; Ernst, Stephan M. A.

    2015-01-01

    A comprehensive evaluation of eight signal pre-processing strategies, including directional microphones, coherence filters, single-channel noise reduction, binaural beamformers, and their combinations, was undertaken with normal-hearing (NH) and hearing-impaired (HI) listeners. Speech reception thresholds (SRTs) were measured in three noise scenarios (multitalker babble, cafeteria noise, and single competing talker). Predictions of three common instrumental measures were compared with the general perceptual benefit caused by the algorithms. The individual SRTs measured without pre-processing and individual benefits were objectively estimated using the binaural speech intelligibility model. Ten listeners with NH and 12 HI listeners participated. The participants varied in age and pure-tone threshold levels. Although HI listeners required a better signal-to-noise ratio to obtain 50% intelligibility than listeners with NH, no differences in SRT benefit from the different algorithms were found between the two groups. With the exception of single-channel noise reduction, all algorithms showed an improvement in SRT of between 2.1 dB (in cafeteria noise) and 4.8 dB (in single competing talker condition). Model predictions with binaural speech intelligibility model explained 83% of the measured variance of the individual SRTs in the no pre-processing condition. Regarding the benefit from the algorithms, the instrumental measures were not able to predict the perceptual data in all tested noise conditions. The comparable benefit observed for both groups suggests a possible application of noise reduction schemes for listeners with different hearing status. Although the model can predict the individual SRTs without pre-processing, further development is necessary to predict the benefits obtained from the algorithms at an individual level. PMID:26721922

  15. Comparing Binaural Pre-processing Strategies I

    PubMed Central

    Krawczyk-Becker, Martin; Marquardt, Daniel; Völker, Christoph; Hu, Hongmei; Herzke, Tobias; Coleman, Graham; Adiloğlu, Kamil; Ernst, Stephan M. A.; Gerkmann, Timo; Doclo, Simon; Kollmeier, Birger; Hohmann, Volker; Dietz, Mathias

    2015-01-01

    In a collaborative research project, several monaural and binaural noise reduction algorithms have been comprehensively evaluated. In this article, eight selected noise reduction algorithms were assessed using instrumental measures, with a focus on the instrumental evaluation of speech intelligibility. Four distinct, reverberant scenarios were created to reflect everyday listening situations: a stationary speech-shaped noise, a multitalker babble noise, a single interfering talker, and a realistic cafeteria noise. Three instrumental measures were employed to assess predicted speech intelligibility and predicted sound quality: the intelligibility-weighted signal-to-noise ratio, the short-time objective intelligibility measure, and the perceptual evaluation of speech quality. The results show substantial improvements in predicted speech intelligibility as well as sound quality for the proposed algorithms. The evaluated coherence-based noise reduction algorithm was able to provide improvements in predicted audio signal quality. For the tested single-channel noise reduction algorithm, improvements in intelligibility-weighted signal-to-noise ratio were observed in all but the nonstationary cafeteria ambient noise scenario. Binaural minimum variance distortionless response beamforming algorithms performed particularly well in all noise scenarios. PMID:26721920

  16. Binaural hearing with electrical stimulation

    PubMed Central

    Kan, Alan; Litovsky, Ruth Y.

    2014-01-01

    Bilateral cochlear implantation is becoming a standard of care in many clinics. While much benefit has been shown through bilateral implantation, patients who have bilateral cochlear implants (CIs) still do not perform as well as normal hearing listeners in sound localization and understanding speech in noisy environments. This difference in performance can arise from a number of different factors, including the areas of hardware and engineering, surgical precision and pathology of the auditory system in deaf persons. While surgical precision and individual pathology are factors that are beyond careful control, improvements can be made in the areas of clinical practice and the engineering of binaural speech processors. These improvements should be grounded in a good understanding of the sensitivities of bilateral CI patients to the acoustic binaural cues that are important to normal hearing listeners for sound localization and speech in noise understanding. To this end, we review the current state-of-the-art in the understanding of the sensitivities of bilateral CI patients to binaural cues in electric hearing, and highlight the important issues and challenges as they relate to clinical practice and the development of new binaural processing strategies. PMID:25193553

  17. Advancing Binaural Cochlear Implant Technology.

    PubMed

    Dietz, Mathias; McAlpine, David

    2015-12-30

    This special issue contains a collection of 13 papers highlighting the collaborative research and engineering project entitled Advancing Binaural Cochlear Implant Technology-ABCIT-as well as research spin-offs from the project. In this introductory editorial, a brief history of the project is provided, alongside an overview of the studies.

  18. Advancing Binaural Cochlear Implant Technology

    PubMed Central

    McAlpine, David

    2015-01-01

    This special issue contains a collection of 13 papers highlighting the collaborative research and engineering project entitled Advancing Binaural Cochlear Implant Technology—ABCIT—as well as research spin-offs from the project. In this introductory editorial, a brief history of the project is provided, alongside an overview of the studies. PMID:26721929

  19. Binaural hearing with electrical stimulation.

    PubMed

    Kan, Alan; Litovsky, Ruth Y

    2015-04-01

    Bilateral cochlear implantation is becoming a standard of care in many clinics. While much benefit has been shown through bilateral implantation, patients who have bilateral cochlear implants (CIs) still do not perform as well as normal hearing listeners in sound localization and understanding speech in noisy environments. This difference in performance can arise from a number of different factors, including the areas of hardware and engineering, surgical precision and pathology of the auditory system in deaf persons. While surgical precision and individual pathology are factors that are beyond careful control, improvements can be made in the areas of clinical practice and the engineering of binaural speech processors. These improvements should be grounded in a good understanding of the sensitivities of bilateral CI patients to the acoustic binaural cues that are important to normal hearing listeners for sound localization and speech in noise understanding. To this end, we review the current state-of-the-art in the understanding of the sensitivities of bilateral CI patients to binaural cues in electric hearing, and highlight the important issues and challenges as they relate to clinical practice and the development of new binaural processing strategies. This article is part of a Special Issue entitled .

  20. Binaural Glimpses at the Cocktail Party?

    PubMed

    Lingner, Andrea; Grothe, Benedikt; Wiegrebe, Lutz; Ewert, Stephan D

    2016-10-01

    Humans often have to focus on a single target sound while ignoring competing maskers in everyday situations. In such conditions, speech intelligibility (SI) is improved when a target speaker is spatially separated from a masker (spatial release from making, SRM) compared to situations where both are co-located. Such asymmetric spatial configurations lead to a 'better-ear effect' with improved signal-to-noise ratio (SNR) at one ear. However, maskers often surround the listener leading to more symmetric configurations where better-ear effects are absent in a long-term, wideband sense. Nevertheless, better-ear glimpses distributed across time and frequency persist and were suggested to account for SRM (Brungart and Iyer 2012). Here, speech reception was assessed using symmetric masker configurations while varying the spatio-temporal distribution of potential better-ear glimpses. Listeners were presented with a frontal target and eight single-talker maskers in four different symmetrical spatial configurations. Compared to the reference condition with co-located target and maskers, an SRM of up to 6 dB was observed. The SRM persisted when the frequency range of the maskers above or below 1500 Hz was replaced with stationary speech-shaped noise. Comparison to a recent short-time binaural SI model showed that better-ear glimpses can account for half the observed SRM, while binaural interaction utilizing phase differences is required to explain the other half. PMID:27412529

  1. Determination of spatial position of multiple targets by ultrasonic binaural method.

    PubMed

    Kazys, R; Mazeika, L

    2002-05-01

    The binaural technique used in ultrasonic sonars has a higher performance speed in comparison with a mechanically scanned ultrasonic beam, however, in presence of multiple targets meets a very serious ambiguity problem. In this case the number of targets detected exceeds the actual number of targets, e.g., there are additional non-existing targets found. Objective of this research was development of a simulation tool enabling to model multi-channel sonar in the environment with multiple targets of arbitrary geometry and development of robust signal processing procedures, suitable for detection of multiple targets from the data collected using the binaural method. The developed software enables to simulate operation of multi-channel sonar in an environment with multiple reflectors and predict a time history of the reflected signals. The novel algorithm for separation of real targets from the virtual ones in presence of multiple targets has been developed. Performance of the proposed algorithm was investigated both in the simulated and a real environment. The results obtained indicate a significant improvement of the sonar performance.

  2. Dynamic binaural sound localization based on variations of interaural time delays and system rotations.

    PubMed

    Baumann, Claude; Rogers, Chris; Massen, Francis

    2015-08-01

    This work develops the mathematical model for a steerable binaural system that determines the instantaneous direction of a sound source in space. The model combines system angular speed and interaural time delays (ITDs) in a differential equation, which allows monitoring the change of source position in the binaural reference frame and therefore resolves the confusion about azimuth and elevation. The work includes the analysis of error propagation and presents results from a real-time application that was performed on a digital signal processing device. Theory and experiments demonstrate that the azimuthal angle to the sound source is accurately yielded in the case of horizontal rotations, whereas the elevation angle is estimated with large uncertainty. This paper also proves the equivalence of the ITD derivative and the Doppler shift appearing between the binaurally captured audio signals. The equation of this Doppler shift is applicable for any kind of motion. It shows that weak binaural pitch differences may represent an additional cue in localization of sound. Finally, the paper develops practical applications from this relationship, such as the synthesizing of binaural images of pure and complex tones emitted by a moving source, and the generation of multiple frequency images for binaural beat experiments. PMID:26328682

  3. Signal detection in the rat.

    PubMed

    HACK, M H

    1963-02-22

    An auditory detection experiment was performed with rats as subjects, and the data were analyzed with a signal detection model. Rats were run at fixed sound pressure levels, and their responses were partitioned so that operating characteristics could be constructed. Measures of detectability, (d(e))((1/2)), were calculated from the operating characteristics, and show that (d(e))((1/2)) is a function of sound pressure levels, rising as these levels rise.

  4. Sound localization in the presence of multiple reflections using a binaurally integrated cross-correlation/auto-correlation mechanism.

    PubMed

    Braasch, Jonas

    2016-07-01

    A precedence effect model is described that can use a binaural signal to robustly localize a sound source in the presence of multiple reflections for the frontal horizontal plane. The model also estimates a room impulse response from a running binaural signal and determines the spatial locations and delays of early reflections, without any prior or additional knowledge of the source. A dual-layer cross-correlation/auto-correlation algorithm is used to determine the interaural time difference of the direct sound source component and to estimate a binaural activity pattern. PMID:27475205

  5. Differential reinforcement and signal detection.

    PubMed

    Nevin, J A; Olson, K; Mandell, C; Yarensky, P

    1975-11-01

    Reinforcement was introduced for responses normally treated as errors in signal-detection procedures. The first experiment used a standard two-response discrete-trial procedure with no reinforcement for errors. Results showed that rats altered their response biases but maintained constant sensitivity to visual signals when reinforcement probabilities varied, and that their sensitivity depended on the physical difference between signals, in accordance with the predictions of signal-detection theory. Experiment II, with rats, and Experiment III, with pigeons, demonstrated that sensitivity decreased in this procedure when reinforcement was scheduled for errors with the signals held constant, despite independence of overall number of reinforcers and sensitivity. Experiment IV, with rats, replicated the decrease in sensitivity in a continuous procedure employing only one response. The decrements in sensitivity were similar across Experiments II, III, and IV, and accorded well with earlier research. Thus, contrary to a fundamental assumption of signal-detection theory, estimates of sensitivity are not always invariant with respect to the outcomes of responding, but depend on relative reinforcement of correct responses.

  6. Wind profiler signal detection improvements

    NASA Technical Reports Server (NTRS)

    Hart, G. F.; Divis, Dale H.

    1992-01-01

    Research is described on potential improvements to the software used with the NASA 49.25 MHz wind profiler located at Kennedy Space Center. In particular, the analysis and results are provided of a study to (1) identify preferred mathematical techniques for the detection of atmospheric signals that provide wind velocities which are obscured by natural and man-made sources, and (2) to analyze one or more preferred techniques to demonstrate proof of the capability to improve the detection of wind velocities.

  7. Rate-constrained source separation for speech enhancement in wireless-communicated binaural hearing aids

    NASA Astrophysics Data System (ADS)

    Ayllón, David; Gil-Pita, Roberto; Rosa-Zurera, Manuel

    2013-12-01

    A recent trend in hearing aids is the connection of the left and right devices to collaborate between them. Binaural systems can provide natural binaural hearing and support the improvement of speech intelligibility in noise, but they require data transmission between both devices, which increases the power consumption. This paper presents a novel sound source separation algorithm for binaural speech enhancement based on supervised machine learning and time-frequency masking. The system is designed considering the power restrictions in hearing aids, constraining both the computational cost of the algorithm and the transmission bit rate. The transmission schema is optimized using a tailored evolutionary algorithm that assigns a different number of bits to each frequency band. The proposed algorithm requires less than 10% of the available computational resources for signal processing and obtains good separation performance using bit rates lower than 64 kbps.

  8. Comparing Binaural Pre-processing Strategies I: Instrumental Evaluation.

    PubMed

    Baumgärtel, Regina M; Krawczyk-Becker, Martin; Marquardt, Daniel; Völker, Christoph; Hu, Hongmei; Herzke, Tobias; Coleman, Graham; Adiloğlu, Kamil; Ernst, Stephan M A; Gerkmann, Timo; Doclo, Simon; Kollmeier, Birger; Hohmann, Volker; Dietz, Mathias

    2015-01-01

    In a collaborative research project, several monaural and binaural noise reduction algorithms have been comprehensively evaluated. In this article, eight selected noise reduction algorithms were assessed using instrumental measures, with a focus on the instrumental evaluation of speech intelligibility. Four distinct, reverberant scenarios were created to reflect everyday listening situations: a stationary speech-shaped noise, a multitalker babble noise, a single interfering talker, and a realistic cafeteria noise. Three instrumental measures were employed to assess predicted speech intelligibility and predicted sound quality: the intelligibility-weighted signal-to-noise ratio, the short-time objective intelligibility measure, and the perceptual evaluation of speech quality. The results show substantial improvements in predicted speech intelligibility as well as sound quality for the proposed algorithms. The evaluated coherence-based noise reduction algorithm was able to provide improvements in predicted audio signal quality. For the tested single-channel noise reduction algorithm, improvements in intelligibility-weighted signal-to-noise ratio were observed in all but the nonstationary cafeteria ambient noise scenario. Binaural minimum variance distortionless response beamforming algorithms performed particularly well in all noise scenarios.

  9. Speech intelligibility improvements with hearing aids using bilateral and binaural adaptive multichannel Wiener filtering based noise reduction.

    PubMed

    Cornelis, Bram; Moonen, Marc; Wouters, Jan

    2012-06-01

    This paper evaluates noise reduction techniques in bilateral and binaural hearing aids. Adaptive implementations (on a real-time test platform) of the bilateral and binaural speech distortion weighted multichannel Wiener filter (SDW-MWF) and a competing bilateral fixed beamformer are evaluated. As the SDW-MWF relies on a voice activity detector (VAD), a realistic binaural VAD is also included. The test subjects (both normal hearing subjects and hearing aid users) are tested by an adaptive speech reception threshold (SRT) test in different spatial scenarios, including a realistic cafeteria scenario with nonstationary noise. The main conclusions are: (a) The binaural SDW-MWF can further improve the SRT (up to 2 dB) over the improvements achieved by bilateral algorithms, although a significant difference is only achievable if the binaural SDW-MWF uses a perfect VAD. However, in the cafeteria scenario only the binaural SDW-MWF achieves a significant SRT improvement (2.6 dB with perfect VAD, 2.2 dB with real VAD), for the group of hearing aid users. (b) There is no significant degradation when using a real VAD at the input signal-to-noise ratio (SNR) levels where the hearing aid users reach their SRT. (c) The bilateral SDW-MWF achieves no SRT improvements compared to the bilateral fixed beamformer.

  10. A Comparison of Two Objective Measures of Binaural Processing

    PubMed Central

    Undurraga, Jaime A.; Marquardt, Torsten; McAlpine, David

    2015-01-01

    There has been continued interest in clinical objective measures of binaural processing. One commonly proposed measure is the binaural interaction component (BIC), which is obtained typically by recording auditory brainstem responses (ABRs)—the BIC reflects the difference between the binaural ABR and the sum of the monaural ABRs (i.e., binaural − (left + right)). We have recently developed an alternative, direct measure of sensitivity to interaural time differences, namely, a following response to modulations in interaural phase difference (the interaural phase modulation following response; IPM-FR). To obtain this measure, an ongoing diotically amplitude-modulated signal is presented, and the interaural phase difference of the carrier is switched periodically at minima in the modulation cycle. Such periodic modulations to interaural phase difference can evoke a steady state following response. BIC and IPM-FR measurements were compared from 10 normal-hearing subjects using a 16-channel electroencephalographic system. Both ABRs and IPM-FRs were observed most clearly from similar electrode locations—differential recordings taken from electrodes near the ear (e.g., mastoid) in reference to a vertex electrode (Cz). Although all subjects displayed clear ABRs, the BIC was not reliably observed. In contrast, the IPM-FR typically elicited a robust and significant response. In addition, the IPM-FR measure required a considerably shorter recording session. As the IPM-FR magnitude varied with interaural phase difference modulation depth, it could potentially serve as a correlate of perceptual salience. Overall, the IPM-FR appears a more suitable clinical measure than the BIC. PMID:26721925

  11. Binaural processing model based on contralateral inhibition. III. Dependence on temporal parameters.

    PubMed

    Breebaart, J; van de Par, S; Kohlrausch, A

    2001-08-01

    This paper and two accompanying papers [Breebaart et al., J. Acoust. Soc. Am. 110, 1074-1088 (2001); 110, 1089-1104 (2001)] describe a computational model for the signal processing of the binaural auditory system. The model consists of several stages of monaural and binaural preprocessing combined with an optimal detector. Simulations of binaural masking experiments were performed as a function of temporal stimulus parameters and compared to psychophysical data adapted from literature. For this purpose, the model was used as an artificial observer in a three-interval, forced-choice procedure. All model parameters were kept constant for all simulations. Model predictions were obtained as a function of the interaural correlation of a masking noise and as a function of both masker and signal duration. Furthermore, maskers with a time-varying interaural correlation were used. Predictions were also obtained for stimuli with time-varying interaural time or intensity differences. Finally, binaural forward-masking conditions were simulated. The results show that the combination of a temporal integrator followed by an optimal detector in the time domain can account for all conditions that were tested, except for those using periodically varying interaural time differences (ITDs) and those measuring interaural correlation just-noticeable differences (jnd's) as a function of bandwidth. PMID:11519578

  12. A Binaural Grouping Model for Predicting Speech Intelligibility in Multitalker Environments

    PubMed Central

    Colburn, H. Steven

    2016-01-01

    Spatially separating speech maskers from target speech often leads to a large intelligibility improvement. Modeling this phenomenon has long been of interest to binaural-hearing researchers for uncovering brain mechanisms and for improving signal-processing algorithms in hearing-assistive devices. Much of the previous binaural modeling work focused on the unmasking enabled by binaural cues at the periphery, and little quantitative modeling has been directed toward the grouping or source-separation benefits of binaural processing. In this article, we propose a binaural model that focuses on grouping, specifically on the selection of time-frequency units that are dominated by signals from the direction of the target. The proposed model uses Equalization-Cancellation (EC) processing with a binary decision rule to estimate a time-frequency binary mask. EC processing is carried out to cancel the target signal and the energy change between the EC input and output is used as a feature that reflects target dominance in each time-frequency unit. The processing in the proposed model requires little computational resources and is straightforward to implement. In combination with the Coherence-based Speech Intelligibility Index, the model is applied to predict the speech intelligibility data measured by Marrone et al. The predicted speech reception threshold matches the pattern of the measured data well, even though the predicted intelligibility improvements relative to the colocated condition are larger than some of the measured data, which may reflect the lack of internal noise in this initial version of the model. PMID:27698261

  13. Coincidence detection in phosphoinositide signaling

    PubMed Central

    Carlton, Jez G.; Cullen, Peter J.

    2006-01-01

    Phosphoinositide lipids function as both signaling molecules and as compartment-specific localization signals for phosphoinositide-binding proteins. In recent years, both phosphoinositides and phosphoinositide-binding proteins have been reported to display a restricted, rather than a uniform, distribution across intracellular membranes. Here, we examine recent data documenting the restricted distribution of both phosphoinositides and phosphoinositide-binding proteins and examine how phosphoinositide-binding proteins might engage multiple binding partners to achieve these restricted localizations, effectively acting as detectors of coincident localization signals. PMID:16139503

  14. Process Dissociation and Mixture Signal Detection Theory

    ERIC Educational Resources Information Center

    DeCarlo, Lawrence T.

    2008-01-01

    The process dissociation procedure was developed in an attempt to separate different processes involved in memory tasks. The procedure naturally lends itself to a formulation within a class of mixture signal detection models. The dual process model is shown to be a special case. The mixture signal detection model is applied to data from a widely…

  15. Perception of Binaural Cues Develops in Children Who Are Deaf through Bilateral Cochlear Implantation

    PubMed Central

    Gordon, Karen A.; Deighton, Michael R.; Abbasalipour, Parvaneh; Papsin, Blake C.

    2014-01-01

    There are significant challenges to restoring binaural hearing to children who have been deaf from an early age. The uncoordinated and poor temporal information available from cochlear implants distorts perception of interaural timing differences normally important for sound localization and listening in noise. Moreover, binaural development can be compromised by bilateral and unilateral auditory deprivation. Here, we studied perception of both interaural level and timing differences in 79 children/adolescents using bilateral cochlear implants and 16 peers with normal hearing. They were asked on which side of their head they heard unilaterally or bilaterally presented click- or electrical pulse- trains. Interaural level cues were identified by most participants including adolescents with long periods of unilateral cochlear implant use and little bilateral implant experience. Interaural timing cues were not detected by new bilateral adolescent users, consistent with previous evidence. Evidence of binaural timing detection was, for the first time, found in children who had much longer implant experience but it was marked by poorer than normal sensitivity and abnormally strong dependence on current level differences between implants. In addition, children with prior unilateral implant use showed a higher proportion of responses to their first implanted sides than children implanted simultaneously. These data indicate that there are functional repercussions of developing binaural hearing through bilateral cochlear implants, particularly when provided sequentially; nonetheless, children have an opportunity to use these devices to hear better in noise and gain spatial hearing. PMID:25531107

  16. Sensitive Infrared Signal Detection by Upconversion Technique

    NASA Technical Reports Server (NTRS)

    Wong, Teh-Hwa; Yu, Jirong; Bai, Yingxin; Johnson, William; Chen, Songsheng; Petros, Mulugeta; Singh, Upendra N.

    2014-01-01

    We demonstrated upconversion assisted detection of a 2.05-micron signal by sum frequency generation to generate a 700-nm light using a bulk periodically poled lithium niobate crystal. The achieved 94% intrinsic upconversion efficiency and 22.58% overall detection efficiency at a pW level of 2.05 micron pave the path to detect extremely weak infrared (IR) signals for remote sensing applications.

  17. Parametric Amplification For Detecting Weak Optical Signals

    NASA Technical Reports Server (NTRS)

    Hemmati, Hamid; Chen, Chien; Chakravarthi, Prakash

    1996-01-01

    Optical-communication receivers of proposed type implement high-sensitivity scheme of optical parametric amplification followed by direct detection for reception of extremely weak signals. Incorporates both optical parametric amplification and direct detection into optimized design enhancing effective signal-to-noise ratios during reception in photon-starved (photon-counting) regime. Eliminates need for complexity of heterodyne detection scheme and partly overcomes limitations imposed on older direct-detection schemes by noise generated in receivers and by limits on quantum efficiencies of photodetectors.

  18. [Weak signal detection in every heart cycle].

    PubMed

    Yuan, J; Xu, X; Gao, D; Shi, G

    2001-12-01

    In this article, a new approach is introduced to lowering the myo-electronic noise in weak ECG signals. We use artificial neural network to make the noise be white, and then we adopt an adaptive filter of which the reference signal is achieved by extracting from other ECG cycle. The outcome is the reduction of both white noise and non-white noise in ECG signal. Satisfactory results have been achieved by using this method in the experiment of late potential detection.

  19. Infrared Signal Detection by Upconversion Technique

    NASA Technical Reports Server (NTRS)

    Wong, Teh-Hwa; Yu, Jirong; Bai, Yingxin; Johnson, William E.

    2014-01-01

    We demonstrated up-conversion assisted detection of a 2.05-micron signal by using a bulk periodically poled Lithium niobate crystal. The 94% intrinsic up-conversion efficiency and 22.58% overall detection efficiency at pW level of 2.05-micron was achieved.

  20. New cognitive detection techniques for multimedia signals

    NASA Astrophysics Data System (ADS)

    Sun, Yixuan; Chakravarty, Sumit

    2015-05-01

    In this paper we are address two issues regarding cognitive radio spectrum sensing. Spectrum sensing for cognitive radio has been extensively studied in recent past and multiple techniques have been proposed. One such technique is entropy based detection. In entropy based detection we measure the entropy of the received signal after converting it to frequency domain. The logic is that in frequency domain, the entropy of noise (assuming its AWGN) is higher than the signal, thereby enabling us to segment noise from signal by using entropy based threshold. This approach however makes some assumptions which may not be valid. It assumes at a time only one of the two( signal / noise) is present. It further assumes that a given test segment is either a signal or a noise segment. The length of the segment in such a scenario would be fixed /known. These assumptions may be too constraining and we propose alternate method to address the above issues. We use a filtering technique in form of Independent Component Analysis to segment the signal and further use additional techniques like energy weight-age to weigh the components to estimate the signal strength. We test our proposed method for a variety of signals include image, audio and sinusoidal signals. Results show the improvement in performance as well as the availability of new measures as generated from our proposed technique.

  1. Modulation and detection of optical signals

    NASA Technical Reports Server (NTRS)

    Goodwin, F. E.

    1972-01-01

    A summary of information is presented which is related to the modulation and detection of information on optical carriers. It emphasizes the treatment of information transfer through an entire system. The most common configurations are considered: intensity modulation, amplitude modulation, frequency or phase modulation, and both direct and coherent detection. In assessing these configurations information capacity and message signal-to-noise ratio are used as a basis of comparison. The physical and geometric treatment of optical heterodyne (or coherent) detection is given.

  2. Monaural Congenital Deafness Affects Aural Dominance and Degrades Binaural Processing

    PubMed Central

    Tillein, Jochen; Hubka, Peter; Kral, Andrej

    2016-01-01

    Cortical development extensively depends on sensory experience. Effects of congenital monaural and binaural deafness on cortical aural dominance and representation of binaural cues were investigated in the present study. We used an animal model that precisely mimics the clinical scenario of unilateral cochlear implantation in an individual with single-sided congenital deafness. Multiunit responses in cortical field A1 to cochlear implant stimulation were studied in normal-hearing cats, bilaterally congenitally deaf cats (CDCs), and unilaterally deaf cats (uCDCs). Binaural deafness reduced cortical responsiveness and decreased response thresholds and dynamic range. In contrast to CDCs, in uCDCs, cortical responsiveness was not reduced, but hemispheric-specific reorganization of aural dominance and binaural interactions were observed. Deafness led to a substantial drop in binaural facilitation in CDCs and uCDCs, demonstrating the inevitable role of experience for a binaural benefit. Sensitivity to interaural time differences was more reduced in uCDCs than in CDCs, particularly at the hemisphere ipsilateral to the hearing ear. Compared with binaural deafness, unilateral hearing prevented nonspecific reduction in cortical responsiveness, but extensively reorganized aural dominance and binaural responses. The deaf ear remained coupled with the cortex in uCDCs, demonstrating a significant difference to deprivation amblyopia in the visual system. PMID:26803166

  3. Intelligent Signal Processing for Detection System Optimization

    SciTech Connect

    Fu, C Y; Petrich, L I; Daley, P F; Burnham, A K

    2004-12-05

    A wavelet-neural network signal processing method has demonstrated approximately tenfold improvement over traditional signal-processing methods for the detection limit of various nitrogen and phosphorus compounds from the output of a thermionic detector attached to a gas chromatograph. A blind test was conducted to validate the lower detection limit. All fourteen of the compound spikes were detected when above the estimated threshold, including all three within a factor of two above the threshold. In addition, two of six spikes were detected at levels of 1/2 the concentration of the nominal threshold. Another two of the six would have been detected correctly if we had allowed human intervention to examine the processed data. One apparent false positive in five nulls was traced to a solvent impurity, whose presence was subsequently identified by analyzing a solvent aliquot evaporated to 1% residual volume, while the other four nulls were properly classified. We view this signal processing method as broadly applicable in analytical chemistry, and we advocate that advanced signal processing methods should be applied as directly as possible to the raw detector output so that less discriminating preprocessing and post-processing does not throw away valuable signal.

  4. Tornado Detection Based on Seismic Signal.

    NASA Astrophysics Data System (ADS)

    Tatom, Frank B.; Knupp, Kevin R.; Vitton, Stanley J.

    1995-02-01

    At the present time the only generally accepted method for detecting when a tornado is on the ground is human observation. Based on theoretical considerations combined with eyewitness testimony, there is strong reason to believe that a tornado in contact with the ground transfers a significant amount of energy into the ground. The amount of energy transferred depends upon the intensity of the tornado and the characteristics of the surface. Some portion of this energy takes the form of seismic waves, both body and surface waves. Surface waves (Rayleigh and possibly Love) represent the most likely type of seismic signal to be detected. Based on the existence of such a signal, a seismic tornado detector appears conceptually possible. The major concerns for designing such a detector are range of detection and discrimination between the tornadic signal and other types of surface waves generated by ground transportation equipment, high winds, or other nontornadic sources.

  5. VLSI processors for signal detection in SETI

    NASA Technical Reports Server (NTRS)

    Duluk, J. F.; Linscott, I. R.; Peterson, A. M.; Burr, J.; Ekroot, B.; Twicken, J.

    1989-01-01

    The objective of the Search for Extraterrestrial Intelligence (SETI) is to locate an artificially created signal coming from a distant star. This is done in two steps: (1) spectral analysis of an incoming radio frequency band, and (2) pattern detection for narrow-band signals. Both steps are computationally expensive and require the development of specially designed computer architectures. To reduce the size and cost of the SETI signal detection machine, two custom VLSI chips are under development. The first chip, the SETI DSP Engine, is used in the spectrum analyzer and is specially designed to compute Discrete Fourier Transforms (DFTs). It is a high-speed arithmetic processor that has two adders, one multiplier-accumulator, and three four-port memories. The second chip is a new type of Content-Addressable Memory. It is the heart of an associative processor that is used for pattern detection. Both chips incorporate many innovative circuits and architectural features.

  6. Intelligent Signal Processing for Detection System Optimization

    SciTech Connect

    Fu, C Y; Petrich, L I; Daley, P F; Burnham, A K

    2004-06-18

    A wavelet-neural network signal processing method has demonstrated approximately tenfold improvement in the detection limit of various nitrogen and phosphorus compounds over traditional signal-processing methods in analyzing the output of a thermionic detector attached to the output of a gas chromatograph. A blind test was conducted to validate the lower detection limit. All fourteen of the compound spikes were detected when above the estimated threshold, including all three within a factor of two above. In addition, two of six were detected at levels 1/2 the concentration of the nominal threshold. We would have had another two correct hits if we had allowed human intervention to examine the processed data. One apparent false positive in five nulls was traced to a solvent impurity, whose presence was identified by running a solvent aliquot evaporated to 1% residual volume, while the other four nulls were properly classified. We view this signal processing method as broadly applicable in analytical chemistry, and we advocate that advanced signal processing methods be applied as directly as possible to the raw detector output so that less discriminating preprocessing and post-processing does not throw away valuable signal.

  7. [Sound localization cues of binaural hearing].

    PubMed

    Paulus, E

    2003-04-01

    The ability to localize sound sources in space is of considerable importance to the human safety- and survival-system. Consequently the current scientific interest in improving the safety-standard i. e. in air-traffic control has provided a new momentum for investigating spatial hearing. This review deals with the nature and the relative salience of the localization cues. Localization refers to judgements of the direction and distance of a sound source but here we will deal with direction only. We begin with a short introduction into the so-called Duplex theory which dates back to John William Strutt (later Lord Rayleigh). The idea is that sound localization is based on interaural time differences (ITD) at low frequencies and interaural level differences (ILD) at high frequencies. If the head remains stationary neither a given ITD nor an ILD can sufficiently define the position of a sound source in space. On such a theoretical basis cones of confusion which open outward from each ear can be predicted ambiguously projecting any source on the surface of such a cone onto an interaural axis. Our restricted ability at localizing sound sources in the vertical median plane is another example of possible ambiguity. At the end of the 19th century scientists already realized that occlusion of the pinnae cavities decreases localization competence. As a result of later achievements in physics and signal-theory it became more obvious that the pinnae may provide an additional cue for spatial hearing and that the outer ear together with the head and the upper torso form a sophisticated direction-dependent filter. The action of such a filter is mathematically described by the so-called Anatomical Transfer Function (ATF). The spectral patterning of the sound produced by the pinnae and the head is most effective when the source has spectral energy over a wide range and contains frequencies above 6 kHz, that is it contains wavelengths short enough to interact with the anatomical

  8. Subliminal stimulation and somatosensory signal detection.

    PubMed

    Ferrè, Elisa Raffaella; Sahani, Maneesh; Haggard, Patrick

    2016-10-01

    Only a small fraction of sensory signals is consciously perceived. The brain's perceptual systems may include mechanisms of feedforward inhibition that protect the cortex from subliminal noise, thus reserving cortical capacity and conscious awareness for significant stimuli. Here we provide a new view of these mechanisms based on signal detection theory, and gain control. We demonstrated that subliminal somatosensory stimulation decreased sensitivity for the detection of a subsequent somatosensory input, largely due to increased false alarm rates. By delivering the subliminal somatosensory stimulus and the to-be-detected somatosensory stimulus to different digits of the same hand, we show that this effect spreads across the sensory surface. In addition, subliminal somatosensory stimulation tended to produce an increased probability of responding "yes", whether the somatosensory stimulus was present or not. Our results suggest that subliminal stimuli temporarily reduce input gain, avoiding excessive responses to further small inputs. This gain control may be automatic, and may precede discriminative classification of inputs into signals or noise. Crucially, we found that subliminal inputs influenced false alarm rates only on blocks where the to-be-detected stimuli were present, and not on pre-test control blocks where they were absent. Participants appeared to adjust their perceptual criterion according to a statistical distribution of stimuli in the current context, with the presence of supraliminal stimuli having an important role in the criterion-setting process. These findings clarify the cognitive mechanisms that reserve conscious perception for salient and important signals.

  9. Detection and frequency tracking of chirping signals

    SciTech Connect

    Elliott, G.R.; Stearns, S.D.

    1990-08-01

    This paper discusses several methods to detect the presence of and track the frequency of a chirping signal in broadband noise. The dynamic behavior of each of the methods is described and tracking error bounds are investigated in terms of the chirp rate. Frequency tracking and behavior in the presence of varying levels of noise are illustrated in examples. 11 refs., 29 figs.

  10. Signal processing aspects of windshear detection

    NASA Technical Reports Server (NTRS)

    Aalfs, David D.; Baxa, Ernest G., Jr.; Bracalente, Emedio M.

    1993-01-01

    Low-altitude windshear (LAWS) has been identified as a major hazard to aircraft, particularly during takeoff and landing. The Federal Aviation Administration (FAA) has been involved with developing technology to detect LAWS. A key element in this technology is high resolution pulse Doppler weather radar equipped with signal and data processing to provide timely information about possible hazardous conditions.

  11. Subliminal stimulation and somatosensory signal detection.

    PubMed

    Ferrè, Elisa Raffaella; Sahani, Maneesh; Haggard, Patrick

    2016-10-01

    Only a small fraction of sensory signals is consciously perceived. The brain's perceptual systems may include mechanisms of feedforward inhibition that protect the cortex from subliminal noise, thus reserving cortical capacity and conscious awareness for significant stimuli. Here we provide a new view of these mechanisms based on signal detection theory, and gain control. We demonstrated that subliminal somatosensory stimulation decreased sensitivity for the detection of a subsequent somatosensory input, largely due to increased false alarm rates. By delivering the subliminal somatosensory stimulus and the to-be-detected somatosensory stimulus to different digits of the same hand, we show that this effect spreads across the sensory surface. In addition, subliminal somatosensory stimulation tended to produce an increased probability of responding "yes", whether the somatosensory stimulus was present or not. Our results suggest that subliminal stimuli temporarily reduce input gain, avoiding excessive responses to further small inputs. This gain control may be automatic, and may precede discriminative classification of inputs into signals or noise. Crucially, we found that subliminal inputs influenced false alarm rates only on blocks where the to-be-detected stimuli were present, and not on pre-test control blocks where they were absent. Participants appeared to adjust their perceptual criterion according to a statistical distribution of stimuli in the current context, with the presence of supraliminal stimuli having an important role in the criterion-setting process. These findings clarify the cognitive mechanisms that reserve conscious perception for salient and important signals. PMID:27387873

  12. Novel digital signal processing and detection techniques

    NASA Astrophysics Data System (ADS)

    Liu, B.

    1981-09-01

    In the area of narrowband signal processing, design rules are developed for optimum decimator and interpolator, a new efficient scheme using recursive filter for decimation/interpolation is proposed, and a novel approach to the computation of narrowband spectra is shown to yield substantial saving over conventional approaches. Results on the implementation of recursive filters with poles near the unit circle that produces significantly reduced roundoff error include a transformation technique, a scheme to modify the quantizer error spectrum, and a new computationally efficient low noise filter structure. In the area of nonclassical signal detection, several results were derived on nonparametric sequential procedures and on the quantization of signal for detection. In addition, a programmable charge transfer device filter is developed, several problems concerning ADPCM are investigated, results are obtained on FFT roundoff error including the prime factor algorithm, and an effective method of generating random sequences is studied.

  13. Carrier synchronization and detection of polyphase signals.

    NASA Technical Reports Server (NTRS)

    Lindsey, W. C.; Simon, M. K.

    1972-01-01

    Digital communication networks used for the distribution of high-speed digital information are currently the subject of design studies for many civil and military applications. This paper presents results that are useful in such studies as well as in network planning. In particular, the paper is concerned with the problems of carrier synchronization and noisy reference detection of polyphase signals. Reconstruction of coherent references for the detection of polyphase signals is considered and analyzed for three carrier reconstruction loops, namely, Nth power (multiply-and-divide) loops, generalized Costas (I-Q) loops, and extensions of data-aided (modulation wipeoff) loops. General expressions for the error probability are developed when the reconstructed reference signals are noisy.

  14. On greenhouse gas signal detection strategies

    SciTech Connect

    Schlesinger, M.E.; Barnett, T.P.

    1989-02-24

    The indisputable detection of a greenhouse gas signal in the global climate system will be a true decision point for mankind. Yet, at this stage of knowledge, the details of an appropriate detection strategy are only beginning to be developed. Two key elements in the eventual strategy are the subject of this report: (1) what variables should be monitored in a detection program, and (2) the comparison of the equilibrium versus transient climate system response. Subsequent sections consider these items in turn while a final section summarizes the main conclusion of the study. 10 refs., 14 figs., 2 tabs.

  15. A Binaural CI Research Platform for Oticon Medical SP/XP Implants Enabling ITD/ILD and Variable Rate Processing.

    PubMed

    Backus, B; Adiloğlu, K; Herzke, T

    2015-12-30

    We present the first portable, binaural, real-time research platform compatible with Oticon Medical SP and XP generation cochlear implants. The platform consists of (a) a pair of behind-the-ear devices, each containing front and rear calibrated microphones, (b) a four-channel USB analog-to-digital converter, (c) real-time PC-based sound processing software called the Master Hearing Aid, and (d) USB-connected hardware and output coils capable of driving two implants simultaneously. The platform is capable of processing signals from the four microphones simultaneously and producing synchronized binaural cochlear implant outputs that drive two (bilaterally implanted) SP or XP implants. Both audio signal preprocessing algorithms (such as binaural beamforming) and novel binaural stimulation strategies (within the implant limitations) can be programmed by researchers. When the whole research platform is combined with Oticon Medical SP implants, interaural electrode timing can be controlled on individual electrodes to within ±1 µs and interaural electrode energy differences can be controlled to within ±2%. Hence, this new platform is particularly well suited to performing experiments related to interaural time differences in combination with interaural level differences in real-time. The platform also supports instantaneously variable stimulation rates and thereby enables investigations such as the effect of changing the stimulation rate on pitch perception. Because the processing can be changed on the fly, researchers can use this platform to study perceptual changes resulting from different processing strategies acutely.

  16. A Binaural CI Research Platform for Oticon Medical SP/XP Implants Enabling ITD/ILD and Variable Rate Processing.

    PubMed

    Backus, B; Adiloğlu, K; Herzke, T

    2015-01-01

    We present the first portable, binaural, real-time research platform compatible with Oticon Medical SP and XP generation cochlear implants. The platform consists of (a) a pair of behind-the-ear devices, each containing front and rear calibrated microphones, (b) a four-channel USB analog-to-digital converter, (c) real-time PC-based sound processing software called the Master Hearing Aid, and (d) USB-connected hardware and output coils capable of driving two implants simultaneously. The platform is capable of processing signals from the four microphones simultaneously and producing synchronized binaural cochlear implant outputs that drive two (bilaterally implanted) SP or XP implants. Both audio signal preprocessing algorithms (such as binaural beamforming) and novel binaural stimulation strategies (within the implant limitations) can be programmed by researchers. When the whole research platform is combined with Oticon Medical SP implants, interaural electrode timing can be controlled on individual electrodes to within ±1 µs and interaural electrode energy differences can be controlled to within ±2%. Hence, this new platform is particularly well suited to performing experiments related to interaural time differences in combination with interaural level differences in real-time. The platform also supports instantaneously variable stimulation rates and thereby enables investigations such as the effect of changing the stimulation rate on pitch perception. Because the processing can be changed on the fly, researchers can use this platform to study perceptual changes resulting from different processing strategies acutely. PMID:26721923

  17. A Binaural CI Research Platform for Oticon Medical SP/XP Implants Enabling ITD/ILD and Variable Rate Processing

    PubMed Central

    Adiloğlu, K.; Herzke, T.

    2015-01-01

    We present the first portable, binaural, real-time research platform compatible with Oticon Medical SP and XP generation cochlear implants. The platform consists of (a) a pair of behind-the-ear devices, each containing front and rear calibrated microphones, (b) a four-channel USB analog-to-digital converter, (c) real-time PC-based sound processing software called the Master Hearing Aid, and (d) USB-connected hardware and output coils capable of driving two implants simultaneously. The platform is capable of processing signals from the four microphones simultaneously and producing synchronized binaural cochlear implant outputs that drive two (bilaterally implanted) SP or XP implants. Both audio signal preprocessing algorithms (such as binaural beamforming) and novel binaural stimulation strategies (within the implant limitations) can be programmed by researchers. When the whole research platform is combined with Oticon Medical SP implants, interaural electrode timing can be controlled on individual electrodes to within ±1 µs and interaural electrode energy differences can be controlled to within ±2%. Hence, this new platform is particularly well suited to performing experiments related to interaural time differences in combination with interaural level differences in real-time. The platform also supports instantaneously variable stimulation rates and thereby enables investigations such as the effect of changing the stimulation rate on pitch perception. Because the processing can be changed on the fly, researchers can use this platform to study perceptual changes resulting from different processing strategies acutely. PMID:26721923

  18. Efficient coding of spectrotemporal binaural sounds leads to emergence of the auditory space representation

    PubMed Central

    Młynarski, Wiktor

    2014-01-01

    To date a number of studies have shown that receptive field shapes of early sensory neurons can be reproduced by optimizing coding efficiency of natural stimulus ensembles. A still unresolved question is whether the efficient coding hypothesis explains formation of neurons which explicitly represent environmental features of different functional importance. This paper proposes that the spatial selectivity of higher auditory neurons emerges as a direct consequence of learning efficient codes for natural binaural sounds. Firstly, it is demonstrated that a linear efficient coding transform—Independent Component Analysis (ICA) trained on spectrograms of naturalistic simulated binaural sounds extracts spatial information present in the signal. A simple hierarchical ICA extension allowing for decoding of sound position is proposed. Furthermore, it is shown that units revealing spatial selectivity can be learned from a binaural recording of a natural auditory scene. In both cases a relatively small subpopulation of learned spectrogram features suffices to perform accurate sound localization. Representation of the auditory space is therefore learned in a purely unsupervised way by maximizing the coding efficiency and without any task-specific constraints. This results imply that efficient coding is a useful strategy for learning structures which allow for making behaviorally vital inferences about the environment. PMID:24639644

  19. The across frequency independence of equalization of interaural time delay in the equalization-cancellation model of binaural unmasking

    NASA Astrophysics Data System (ADS)

    Akeroyd, Michael A.

    2004-08-01

    The equalization stage in the equalization-cancellation model of binaural unmasking compensates for the interaural time delay (ITD) of a masking noise by introducing an opposite, internal delay [N. I. Durlach, in Foundations of Modern Auditory Theory, Vol. II., edited by J. V. Tobias (Academic, New York, 1972)]. Culling and Summerfield [J. Acoust. Soc. Am. 98, 785-797 (1995)] developed a multi-channel version of this model in which equalization was ``free'' to use the optimal delay in each channel. Two experiments were conducted to test if equalization was indeed free or if it was ``restricted'' to the same delay in all channels. One experiment measured binaural detection thresholds, using an adaptive procedure, for 1-, 5-, or 17-component tones against a broadband masking noise, in three binaural configurations (N0S180, N180S0, and N90S270). The thresholds for the 1-component stimuli were used to normalize the levels of each of the 5- and 17-component stimuli so that they were equally detectable. If equalization was restricted, then, for the 5- and 17-component stimuli, the N90S270 and N180S0 configurations would yield a greater threshold than the N0S180 configurations. No such difference was found. A subsequent experiment measured binaural detection thresholds, via psychometric functions, for a 2-component complex tone in the same three binaural configurations. Again, no differential effect of configuration was observed. An analytic model of the detection of a complex tone showed that the results were more consistent with free equalization than restricted equalization, although the size of the differences was found to depend on the shape of the psychometric function for detection.

  20. Signal detection and noise suppression using a wavelet transform signal processor: application to ultrasonic flaw detection.

    PubMed

    Abbate, A; Koay, J; Frankel, J; Schroeder, S C; Das, P

    1997-01-01

    The utilization of signal processing techniques in nondestructive testing, especially in ultrasonics, is widespread. Signal averaging, matched filtering, frequency spectrum analysis, neural nets, and autoregressive analysis have all been used to analyze ultrasonic signals. The Wavelet Transform (WT) is the most recent technique for processing signals with time-varying spectra. Interest in wavelets and their potential applications has resulted in an explosion of papers; some have called the wavelets the most significant mathematical event of the past decade. In this work, the Wavelet Transform is utilized to improve ultrasonic flaw detection in noisy signals as an alternative to the Split-Spectrum Processing (SSP) technique. In SSP, the frequency spectrum of the signal is split using overlapping Gaussian passband filters with different central frequencies and fixed absolute bandwidth. A similar approach is utilized in the WT, but in this case the relative bandwidth is constant, resulting in a filter bank with a self-adjusting window structure that can display the temporal variation of the signal's spectral components with varying resolutions. This property of the WT is extremely useful for detecting flaw echoes embedded in background noise. The detection of ultrasonic pulses using the wavelet transform is described and numerical results show good detection even for signal-to-noise ratios (SNR) of -15 dB. The improvement in detection was experimentally verified using steel samples with simulated flaws.

  1. Acoustic signal detection of manatee calls

    NASA Astrophysics Data System (ADS)

    Niezrecki, Christopher; Phillips, Richard; Meyer, Michael; Beusse, Diedrich O.

    2003-04-01

    The West Indian manatee (trichechus manatus latirostris) has become endangered partly because of a growing number of collisions with boats. A system to warn boaters of the presence of manatees, that can signal to boaters that manatees are present in the immediate vicinity, could potentially reduce these boat collisions. In order to identify the presence of manatees, acoustic methods are employed. Within this paper, three different detection algorithms are used to detect the calls of the West Indian manatee. The detection systems are tested in the laboratory using simulated manatee vocalizations from an audio compact disc. The detection method that provides the best overall performance is able to correctly identify ~=96% of the manatee vocalizations. However the system also results in a false positive rate of ~=16%. The results of this work may ultimately lead to the development of a manatee warning system that can warn boaters of the presence of manatees.

  2. Optimum Detection of Frequency-Hopped Signals

    NASA Technical Reports Server (NTRS)

    Cheng, Unjeng; Levitt, Barry; Polydoros, Andreas; Simon, Marvin K.

    1992-01-01

    This paper derives and analyzes optimum and near-optimum structures for detecting frequency-hopped (FH) signals with arbitrary modulation in additive white Gaussian noise. The principalmodulation formats considered are M-ary frequency-shift-keying (MFSK) with fast frequency hopping(FFH) wherein a single tone is transmitted per hop, and slow frequency hopping (SFH) with multipleMFSK tones (data symbols) per hop. The SFH detection category has not previously been addressedin the open literature and its analysis is generally more complex than FFH.

  3. Automated detection and location of indications in eddy current signals

    DOEpatents

    Brudnoy, David M.; Oppenlander, Jane E.; Levy, Arthur J.

    2000-01-01

    A computer implemented information extraction process that locates and identifies eddy current signal features in digital point-ordered signals, signals representing data from inspection of test materials, by enhancing the signal features relative to signal noise, detecting features of the signals, verifying the location of the signal features that can be known in advance, and outputting information about the identity and location of all detected signal features.

  4. Sensing Methods for Detecting Analog Television Signals

    NASA Astrophysics Data System (ADS)

    Rahman, Mohammad Azizur; Song, Chunyi; Harada, Hiroshi

    This paper introduces a unified method of spectrum sensing for all existing analog television (TV) signals including NTSC, PAL and SECAM. We propose a correlation based method (CBM) with a single reference signal for sensing any analog TV signals. In addition we also propose an improved energy detection method. The CBM approach has been implemented in a hardware prototype specially designed for participating in Singapore TV white space (WS) test trial conducted by Infocomm Development Authority (IDA) of the Singapore government. Analytical and simulation results of the CBM method will be presented in the paper, as well as hardware testing results for sensing various analog TV signals. Both AWGN and fading channels will be considered. It is shown that the theoretical results closely match with those from simulations. Sensing performance of the hardware prototype will also be presented in fading environment by using a fading simulator. We present performance of the proposed techniques in terms of probability of false alarm, probability of detection, sensing time etc. We also present a comparative study of the various techniques.

  5. Community detection by signaling on complex networks

    NASA Astrophysics Data System (ADS)

    Hu, Yanqing; Li, Menghui; Zhang, Peng; Fan, Ying; di, Zengru

    2008-07-01

    Based on a signaling process of complex networks, a method for identification of community structure is proposed. For a network with n nodes, every node is assumed to be a system which can send, receive, and record signals. Each node is taken as the initial signal source to excite the whole network one time. Then the source node is associated with an n -dimensional vector which records the effects of the signaling process. By this process, the topological relationship of nodes on the network could be transferred into a geometrical structure of vectors in n -dimensional Euclidean space. Then the best partition of groups is determined by F statistics and the final community structure is given by the K -means clustering method. This method can detect community structure both in unweighted and weighted networks. It has been applied to ad hoc networks and some real networks such as the Zachary karate club network and football team network. The results indicate that the algorithm based on the signaling process works well.

  6. Detection and Classification of Whale Acoustic Signals

    NASA Astrophysics Data System (ADS)

    Xian, Yin

    This dissertation focuses on two vital challenges in relation to whale acoustic signals: detection and classification. In detection, we evaluated the influence of the uncertain ocean environment on the spectrogram-based detector, and derived the likelihood ratio of the proposed Short Time Fourier Transform detector. Experimental results showed that the proposed detector outperforms detectors based on the spectrogram. The proposed detector is more sensitive to environmental changes because it includes phase information. In classification, our focus is on finding a robust and sparse representation of whale vocalizations. Because whale vocalizations can be modeled as polynomial phase signals, we can represent the whale calls by their polynomial phase coefficients. In this dissertation, we used the Weyl transform to capture chirp rate information, and used a two dimensional feature set to represent whale vocalizations globally. Experimental results showed that our Weyl feature set outperforms chirplet coefficients and MFCC (Mel Frequency Cepstral Coefficients) when applied to our collected data. Since whale vocalizations can be represented by polynomial phase coefficients, it is plausible that the signals lie on a manifold parameterized by these coefficients. We also studied the intrinsic structure of high dimensional whale data by exploiting its geometry. Experimental results showed that nonlinear mappings such as Laplacian Eigenmap and ISOMAP outperform linear mappings such as PCA and MDS, suggesting that the whale acoustic data is nonlinear. We also explored deep learning algorithms on whale acoustic data. We built each layer as convolutions with either a PCA filter bank (PCANet) or a DCT filter bank (DCTNet). With the DCT filter bank, each layer has different a time-frequency scale representation, and from this, one can extract different physical information. Experimental results showed that our PCANet and DCTNet achieve high classification rate on the whale

  7. Aging effects on the binaural interaction component of the auditory brainstem response in the Mongolian gerbil: Effects of interaural time and level differences.

    PubMed

    Laumen, Geneviève; Tollin, Daniel J; Beutelmann, Rainer; Klump, Georg M

    2016-07-01

    The effect of interaural time difference (ITD) and interaural level difference (ILD) on wave 4 of the binaural and summed monaural auditory brainstem responses (ABRs) as well as on the DN1 component of the binaural interaction component (BIC) of the ABR in young and old Mongolian gerbils (Meriones unguiculatus) was investigated. Measurements were made at a fixed sound pressure level (SPL) and a fixed level above visually detected ABR threshold to compensate for individual hearing threshold differences. In both stimulation modes (fixed SPL and fixed level above visually detected ABR threshold) an effect of ITD on the latency and the amplitude of wave 4 as well as of the BIC was observed. With increasing absolute ITD values BIC latencies were increased and amplitudes were decreased. ILD had a much smaller effect on these measures. Old animals showed a reduced amplitude of the DN1 component. This difference was due to a smaller wave 4 in the summed monaural ABRs of old animals compared to young animals whereas wave 4 in the binaural-evoked ABR showed no age-related difference. In old animals the small amplitude of the DN1 component was correlated with small binaural-evoked wave 1 and wave 3 amplitudes. This suggests that the reduced peripheral input affects central binaural processing which is reflected in the BIC. PMID:27173973

  8. Compressive Detection of Random Subspace Signals

    NASA Astrophysics Data System (ADS)

    Razavi, Alireza; Valkama, Mikko; Cabric, Danijela

    2016-08-01

    The problem of compressive detection of random subspace signals is studied. We consider signals modeled as $\\mathbf{s} = \\mathbf{H} \\mathbf{x}$ where $\\mathbf{H}$ is an $N \\times K$ matrix with $K \\le N$ and $\\mathbf{x} \\sim \\mathcal{N}(\\mathbf{0}_{K,1},\\sigma_x^2 \\mathbf{I}_K)$. We say that signal $\\mathbf{s}$ lies in or leans toward a subspace if the largest eigenvalue of $\\mathbf{H} \\mathbf{H}^T$ is strictly greater than its smallest eigenvalue. We first design a measurement matrix $\\mathbf{\\Phi}=[\\mathbf{\\Phi}_s^T,\\mathbf{\\Phi}_o^T]^T$ comprising of two sub-matrices $\\mathbf{\\Phi}_s$ and $\\mathbf{\\Phi}_o$ where $\\mathbf{\\Phi}_s$ projects the signals to the strongest left-singular vectors, i.e., the left-singular vectors corresponding to the largest singular values, of subspace matrix $\\mathbf{H}$ and $\\mathbf{\\Phi}_o$ projects it to the weakest left-singular vectors. We then propose two detectors which work based on the difference in energies of the samples measured by two sub-matrices $\\mathbf{\\Phi}_s$ and $\\mathbf{\\Phi}_o$ and prove their optimality. Simplified versions of the proposed detectors for the case when the variance of noise is known are also provided. Furthermore, we study the performance of the detector when measurements are imprecise and show how imprecision can be compensated by employing more measurement devices. The problem is then re-formulated for the case when the signal lies in the union of a finite number of linear subspaces instead of a single linear subspace. Finally, we study the performance of the proposed methods by simulation examples.

  9. Signal Injection as a Fault Detection Technique

    PubMed Central

    Cusidó, Jordi; Romeral, Luis; Ortega, Juan Antonio; Garcia, Antoni; Riba, Jordi

    2011-01-01

    Double frequency tests are used for evaluating stator windings and analyzing the temperature. Likewise, signal injection on induction machines is used on sensorless motor control fields to find out the rotor position. Motor Current Signature Analysis (MCSA), which focuses on the spectral analysis of stator current, is the most widely used method for identifying faults in induction motors. Motor faults such as broken rotor bars, bearing damage and eccentricity of the rotor axis can be detected. However, the method presents some problems at low speed and low torque, mainly due to the proximity between the frequencies to be detected and the small amplitude of the resulting harmonics. This paper proposes the injection of an additional voltage into the machine being tested at a frequency different from the fundamental one, and then studying the resulting harmonics around the new frequencies appearing due to the composition between injected and main frequencies. PMID:22163801

  10. Detecting double compression of audio signal

    NASA Astrophysics Data System (ADS)

    Yang, Rui; Shi, Yun Q.; Huang, Jiwu

    2010-01-01

    MP3 is the most popular audio format nowadays in our daily life, for example music downloaded from the Internet and file saved in the digital recorder are often in MP3 format. However, low bitrate MP3s are often transcoded to high bitrate since high bitrate ones are of high commercial value. Also audio recording in digital recorder can be doctored easily by pervasive audio editing software. This paper presents two methods for the detection of double MP3 compression. The methods are essential for finding out fake-quality MP3 and audio forensics. The proposed methods use support vector machine classifiers with feature vectors formed by the distributions of the first digits of the quantized MDCT (modified discrete cosine transform) coefficients. Extensive experiments demonstrate the effectiveness of the proposed methods. To the best of our knowledge, this piece of work is the first one to detect double compression of audio signal.

  11. Signal injection as a fault detection technique.

    PubMed

    Cusidó, Jordi; Romeral, Luis; Ortega, Juan Antonio; Garcia, Antoni; Riba, Jordi

    2011-01-01

    Double frequency tests are used for evaluating stator windings and analyzing the temperature. Likewise, signal injection on induction machines is used on sensorless motor control fields to find out the rotor position. Motor Current Signature Analysis (MCSA), which focuses on the spectral analysis of stator current, is the most widely used method for identifying faults in induction motors. Motor faults such as broken rotor bars, bearing damage and eccentricity of the rotor axis can be detected. However, the method presents some problems at low speed and low torque, mainly due to the proximity between the frequencies to be detected and the small amplitude of the resulting harmonics. This paper proposes the injection of an additional voltage into the machine being tested at a frequency different from the fundamental one, and then studying the resulting harmonics around the new frequencies appearing due to the composition between injected and main frequencies. PMID:22163801

  12. Tone-in-noise detection using envelope cues: comparison of signal-processing-based and physiological models.

    PubMed

    Mao, Junwen; Carney, Laurel H

    2015-02-01

    Tone-in-noise detection tasks with reproducible noise maskers have been used to identify cues that listeners use to detect signals in noisy environments. Previous studies have shown that energy, envelope, and fine-structure cues are significantly correlated to listeners' performance for detection of a 500-Hz tone in noise. In this study, envelope cues were examined for both diotic and dichotic tone-in-noise detection using both stimulus-based signal processing and physiological models. For stimulus-based envelope cues, a modified envelope slope model was used for the diotic condition and the binaural slope of the interaural envelope difference model for the dichotic condition. Stimulus-based models do not include key nonlinear transformations in the auditory periphery such as compression, rate and dynamic range adaptation, and rate saturation, all of which affect the encoding of the stimulus envelope. For physiological envelope cues, stimuli were passed through models for the auditory nerve (AN), cochlear nucleus, and inferior colliculus (IC). The AN and cochlear nucleus models included appropriate modulation gain, another transformation of the stimulus envelope that is not typically included in stimulus-based models. A model IC cell was simulated with a linear band-pass modulation filter. The average discharge rate and response fluctuations of the model IC cell were compared to human performance. Previous studies have predicted a significant amount of the variance across reproducible noise maskers in listeners' detection using stimulus-based envelope cues. In this study, a physiological model that includes neural mechanisms that affect encoding of the stimulus envelope predicts a similar amount of the variance in listeners' performance across noise maskers. PMID:25266265

  13. Tone-in-noise detection using envelope cues: comparison of signal-processing-based and physiological models.

    PubMed

    Mao, Junwen; Carney, Laurel H

    2015-02-01

    Tone-in-noise detection tasks with reproducible noise maskers have been used to identify cues that listeners use to detect signals in noisy environments. Previous studies have shown that energy, envelope, and fine-structure cues are significantly correlated to listeners' performance for detection of a 500-Hz tone in noise. In this study, envelope cues were examined for both diotic and dichotic tone-in-noise detection using both stimulus-based signal processing and physiological models. For stimulus-based envelope cues, a modified envelope slope model was used for the diotic condition and the binaural slope of the interaural envelope difference model for the dichotic condition. Stimulus-based models do not include key nonlinear transformations in the auditory periphery such as compression, rate and dynamic range adaptation, and rate saturation, all of which affect the encoding of the stimulus envelope. For physiological envelope cues, stimuli were passed through models for the auditory nerve (AN), cochlear nucleus, and inferior colliculus (IC). The AN and cochlear nucleus models included appropriate modulation gain, another transformation of the stimulus envelope that is not typically included in stimulus-based models. A model IC cell was simulated with a linear band-pass modulation filter. The average discharge rate and response fluctuations of the model IC cell were compared to human performance. Previous studies have predicted a significant amount of the variance across reproducible noise maskers in listeners' detection using stimulus-based envelope cues. In this study, a physiological model that includes neural mechanisms that affect encoding of the stimulus envelope predicts a similar amount of the variance in listeners' performance across noise maskers.

  14. A Diagonal-Steering-Based Binaural Beamforming Algorithm Incorporating a Diagonal Speech Localizer for Persons With Bilateral Hearing Impairment.

    PubMed

    Lee, Jun Chang; Nam, Kyoung Won; Jang, Dong Pyo; Kim, In Young

    2015-12-01

    Previously suggested diagonal-steering algorithms for binaural hearing support devices have commonly assumed that the direction of the speech signal is known in advance, which is not always the case in many real circumstances. In this study, a new diagonal-steering-based binaural speech localization (BSL) algorithm is proposed, and the performances of the BSL algorithm and the binaural beamforming algorithm, which integrates the BSL and diagonal-steering algorithms, were evaluated using actual speech-in-noise signals in several simulated listening scenarios. Testing sounds were recorded in a KEMAR mannequin setup and two objective indices, improvements in signal-to-noise ratio (SNRi ) and segmental SNR (segSNRi ), were utilized for performance evaluation. Experimental results demonstrated that the accuracy of the BSL was in the 90-100% range when input SNR was -10 to +5 dB range. The average differences between the γ-adjusted and γ-fixed diagonal-steering algorithms (for -15 to +5 dB input SNR) in the talking in the restaurant scenario were 0.203-0.937 dB for SNRi and 0.052-0.437 dB for segSNRi , and in the listening while car driving scenario, the differences were 0.387-0.835 dB for SNRi and 0.259-1.175 dB for segSNRi . In addition, the average difference between the BSL-turned-on and the BSL-turned-off cases for the binaural beamforming algorithm in the listening while car driving scenario was 1.631-4.246 dB for SNRi and 0.574-2.784 dB for segSNRi . In all testing conditions, the γ-adjusted diagonal-steering and BSL algorithm improved the values of the indices more than the conventional algorithms. The binaural beamforming algorithm, which integrates the proposed BSL and diagonal-steering algorithm, is expected to improve the performance of the binaural hearing support devices in noisy situations.

  15. Binaural effects in simultaneous room reflection masking

    NASA Astrophysics Data System (ADS)

    Buchholz, Joerg M.

    2005-04-01

    Masked thresholds (MT) for a single test reflection masked by a direct sound (200 ms long broadband noise) were measured dependent on the time delay of the reflection for diotic as well as dichotic stimulus presentation. In the diotic case, the direct sound and the test reflection were presented equally to both ears via headphones. In the dichotic case, an ITD of 0.5 ms was added to the test reflection. In order to focus on simultaneous masking effects, the reflection was truncated in such a way that it formed a common offset with the direct sound. For the diotic case, the resulting data showed a MT increase with increasing reflection delay and for the dichotic case a MT decrease with increasing reflection delay, producing an intercept between both curves at a reflection delay of 6-8 ms. Hence, negative BMLDs (up to -8 dB) were found for very early reflections and positive BMLDs (up to +8 dB) for later reflections, suggesting a binaural mechanism that suppresses very early reflections and enhances later reflections. The measurement results are discussed in the background of different auditory models.

  16. Ultrasound perfusion signal processing for tumor detection

    NASA Astrophysics Data System (ADS)

    Kim, MinWoo; Abbey, Craig K.; Insana, Michael F.

    2016-04-01

    Enhanced blood perfusion in a tissue mass is an indication of neo-vascularity and a sign of a potential malignancy. Ultrasonic pulsed-Doppler imaging is a preferred modality for noninvasive monitoring of blood flow. However, the weak blood echoes and disorganized slow flow make it difficult to detect perfusion using standard methods without the expense and risk of contrast enhancement. Our research measures the efficiency of conventional power-Doppler (PD) methods at discriminating flow states by comparing measurement performance to that of an ideal discriminator. ROC analysis applied to the experimental results shows that power Doppler methods are just 30-50 % efficient at perfusion flows less than 1ml/min, suggesting an opportunity to improve perfusion assessment through signal processing. A new perfusion estimator is proposed by extending the statistical discriminator approach. We show that 2-D perfusion color imaging may be enhanced using this approach.

  17. Using a binaural biomimetic array to identify bottom objects ensonified by echolocating dolphins.

    PubMed

    Helweg, David A; Moore, Patrick W; Martin, Stephen W; Dankiewicz, Lois A

    2006-06-01

    The development of a unique dolphin biomimetic sonar produced data that were used to study signal processing methods for object identification. Echoes from four metallic objects proud on the bottom, and a substrate-only condition, were generated by bottlenose dolphins trained to ensonify the targets in very shallow water. Using the two-element ('binaural') receive array, object echo spectra were collected and submitted for identification to four neural network architectures. Identification accuracy was evaluated over two receive array configurations, and five signal processing schemes. The four neural networks included backpropagation, learning vector quantization, genetic learning and probabilistic network architectures. The processing schemes included four methods that capitalized on the binaural data, plus a monaural benchmark process. All the schemes resulted in above-chance identification accuracy when applied to learning vector quantization and backpropagation. Beam-forming or concatenation of spectra from both receive elements outperformed the monaural benchmark, with higher sensitivity and lower bias. Ultimately, best object identification performance was achieved by the learning vector quantization network supplied with beam-formed data. The advantages of multi-element signal processing for object identification are clearly demonstrated in this development of a first-ever dolphin biomimetic sonar.

  18. Using a binaural biomimetic array to identify bottom objects ensonified by echolocating dolphins

    USGS Publications Warehouse

    Heiweg, D.A.; Moore, P.W.; Martin, S.W.; Dankiewicz, L.A.

    2006-01-01

    The development of a unique dolphin biomimetic sonar produced data that were used to study signal processing methods for object identification. Echoes from four metallic objects proud on the bottom, and a substrate-only condition, were generated by bottlenose dolphins trained to ensonify the targets in very shallow water. Using the two-element ('binaural') receive array, object echo spectra were collected and submitted for identification to four neural network architectures. Identification accuracy was evaluated over two receive array configurations, and five signal processing schemes. The four neural networks included backpropagation, learning vector quantization, genetic learning and probabilistic network architectures. The processing schemes included four methods that capitalized on the binaural data, plus a monaural benchmark process. All the schemes resulted in above-chance identification accuracy when applied to learning vector quantization and backpropagation. Beam-forming or concatenation of spectra from both receive elements outperformed the monaural benchmark, with higher sensitivity and lower bias. Ultimately, best object identification performance was achieved by the learning vector quantization network supplied with beam-formed data. The advantages of multi-element signal processing for object identification are clearly demonstrated in this development of a first-ever dolphin biomimetic sonar. ?? 2006 IOP Publishing Ltd.

  19. Structural Changes and Lack of HCN1 Channels in the Binaural Auditory Brainstem of the Naked Mole-Rat (Heterocephalus glaber).

    PubMed

    Gessele, Nikodemus; Garcia-Pino, Elisabet; Omerbašić, Damir; Park, Thomas J; Koch, Ursula

    2016-01-01

    Naked mole-rats (Heterocephalus glaber) live in large eu-social, underground colonies in narrow burrows and are exposed to a large repertoire of communication signals but negligible binaural sound localization cues, such as interaural time and intensity differences. We therefore asked whether monaural and binaural auditory brainstem nuclei in the naked mole-rat are differentially adjusted to this acoustic environment. Using antibody stainings against excitatory and inhibitory presynaptic structures, namely the vesicular glutamate transporter VGluT1 and the glycine transporter GlyT2 we identified all major auditory brainstem nuclei except the superior paraolivary nucleus in these animals. Naked mole-rats possess a well structured medial superior olive, with a similar synaptic arrangement to interaural-time-difference encoding animals. The neighboring lateral superior olive, which analyzes interaural intensity differences, is large and elongated, whereas the medial nucleus of the trapezoid body, which provides the contralateral inhibitory input to these binaural nuclei, is reduced in size. In contrast, the cochlear nucleus, the nuclei of the lateral lemniscus and the inferior colliculus are not considerably different when compared to other rodent species. Most interestingly, binaural auditory brainstem nuclei lack the membrane-bound hyperpolarization-activated channel HCN1, a voltage-gated ion channel that greatly contributes to the fast integration times in binaural nuclei of the superior olivary complex in other species. This suggests substantially lengthened membrane time constants and thus prolonged temporal integration of inputs in binaural auditory brainstem neurons and might be linked to the severely degenerated sound localization abilities in these animals.

  20. Structural Changes and Lack of HCN1 Channels in the Binaural Auditory Brainstem of the Naked Mole-Rat (Heterocephalus glaber)

    PubMed Central

    Gessele, Nikodemus; Garcia-Pino, Elisabet; Omerbašić, Damir; Park, Thomas J.; Koch, Ursula

    2016-01-01

    Naked mole-rats (Heterocephalus glaber) live in large eu-social, underground colonies in narrow burrows and are exposed to a large repertoire of communication signals but negligible binaural sound localization cues, such as interaural time and intensity differences. We therefore asked whether monaural and binaural auditory brainstem nuclei in the naked mole-rat are differentially adjusted to this acoustic environment. Using antibody stainings against excitatory and inhibitory presynaptic structures, namely the vesicular glutamate transporter VGluT1 and the glycine transporter GlyT2 we identified all major auditory brainstem nuclei except the superior paraolivary nucleus in these animals. Naked mole-rats possess a well structured medial superior olive, with a similar synaptic arrangement to interaural-time-difference encoding animals. The neighboring lateral superior olive, which analyzes interaural intensity differences, is large and elongated, whereas the medial nucleus of the trapezoid body, which provides the contralateral inhibitory input to these binaural nuclei, is reduced in size. In contrast, the cochlear nucleus, the nuclei of the lateral lemniscus and the inferior colliculus are not considerably different when compared to other rodent species. Most interestingly, binaural auditory brainstem nuclei lack the membrane-bound hyperpolarization-activated channel HCN1, a voltage-gated ion channel that greatly contributes to the fast integration times in binaural nuclei of the superior olivary complex in other species. This suggests substantially lengthened membrane time constants and thus prolonged temporal integration of inputs in binaural auditory brainstem neurons and might be linked to the severely degenerated sound localization abilities in these animals. PMID:26760498

  1. Detection of Transient Signals from Extraterrestrial Technologies

    NASA Astrophysics Data System (ADS)

    Tarter, J. C.

    2003-05-01

    If you were an engineer and wanted to build a beacon with which to attract the attention of any emerging technological civilizations in the Milky Way galaxy, how would you do it? SETI 2020: A Roadmap for the Search for Extraterrestrial Intelligence (a recent report of the SETI Science and Technology Working Group) describes a number of different beacon scenarios, as well as examples of leakage radiation, all of which would lead to signal types that appear as transients in the sky of any given receiving civilization. Most SETI searches to date have been ill-matched to the problem of finding transient signals; the dwell time on source has been short, and the same directions have not been revisited very often. Both the Omnidirectional SETI System (OSS) proposed in SETI 2020, and the Allen Telescope Array (ATA) will offer greatly improved opportunities for detecting radio transients, whether they are from technological or astrophysical sources. The ATA should be operational within a few years, but the OSS will not be affordable until Moore's Law has significantly reduced the cost for the compute power needed to form all beams on the sky and all frequency channels in the spectrometers. This is estimated to be { ˜ 1016}-10{21} ops depending on the total collecting area of the array. Nevertheless, the opportunity to build a radio-fly's-eye or radio camera (suggested by Robert Dixon in 1988) is now getting close enough to warrant prototyping and construction of small size arrays and receivers; several programs are underway.

  2. Detection of antipodal signalling and its application to wideband SETI

    NASA Astrophysics Data System (ADS)

    Morrison, Ian S.

    2012-09-01

    The SETI community is becoming increasingly interested in extending its searches to include wideband signals, such as information-bearing beacons. However, prior to discovery of a target signal, a SETI receiver has no knowledge of the signal parameters (bandwidth, carrier frequency, modulation type, etc.) and so detection can be very challenging, especially at low signal-to-noise ratios. However, this paper shows by example that there exist signal classes and corresponding detection methods that permit straightforward discovery of wideband signals of unknown structure. The example given is a form of binary antipodal signalling that utilises spread-spectrum modulation, which offers benefits to the receiver in terms of immunity to noise/interference and ease of detection. The proposed detection method is a 'symbol-wise' autocorrelation process that takes advantage of the cyclostationarity property of modulated signals. Detection sensitivity is suboptimal in comparison with what is possible if the target signal structure is known. However, this deficit can be overcome by processing longer timespans of signal, providing scope for detection at extremely low signal-to-noise ratios. It is postulated that antipodal signalling represents an attractive option for interstellar beacons because it is both power efficient and there exists a simple complementary detection method not requiring explicit coordination between the transmitter and receiver. This in turn suggests there is a case for extending future SETI searches to include this class of signal.

  3. Boundary extension: Insights from signal detection theory.

    PubMed

    Liu, Zili; Yang, Xiaoyang; Intraub, Helene

    2016-06-01

    After viewing a scene, people often remember having seen more of the world than was originally visible, an error referred to as boundary extension. Despite the large number of studies on this phenomenon, performance has never been considered in terms of signal detection theory (SDT). We report two visual memory experiments that allowed us to explore boundary extension in terms of SDT. In our experiments, participants first studied pictures presented as close-up or wide-angle views. At test, either the identical view or a different view (a closer or wider angle version of the same scene) were presented and participants rated the test image as being the same or different than before on a 6-point scale. We found that both discrimination sensitivity and bias contributed to the boundary extension effect. The discrimination sensitivity difference was at least 28%, and its presence refuted the hypothesis that boundary extension was due solely to participants' response bias to label test pictures as more wide-angled. Instead, our results support the idea that participants' responses reflect false memory beyond the view (i.e., a more wide-angle view of the world). PMID:27281464

  4. Embolic Doppler ultrasound signal detection via fractional Fourier transform.

    PubMed

    Gençer, Merve; Bilgin, Gökhan; Aydın, Nizamettin

    2013-01-01

    Computerized analysis of Doppler ultrasound signals can aid early detection of asymptomatic circulating emboli. For analysis, physicians use informative features extracted from Doppler ultrasound signals. Time -frequency analysis methods are useful tools to exploit the transient like signals such as Embolic signals. Detection of discriminative features would be the first step toward automated analysis of embolic Doppler ultrasound signals. The most problematic part of setting up emboli detection system is to differentiate embolic signals from confusing similar wave-like patterns such as Doppler speckle and artifacts caused by tissue movement, probe tapping, speaking etc. In this study, discrete version of fractional Fourier transform is presented as a solution in the detection of emboli in digitized Doppler ultrasound signals. An accurate set of parameters are extracted using short time Fourier transform and fractional Fourier transform and the results are compared to reveal detection quality. Experimental results prove the efficiency of fractional Fourier transform in which discriminative features becomes more evident.

  5. Subaperture clutter filter with CFAR signal detection

    DOEpatents

    Ormesher, Richard C.; Naething, Richard M.

    2016-08-30

    The various technologies presented herein relate to the determination of whether a received signal comprising radar clutter further comprises a communication signal. The communication signal can comprise of a preamble, a data symbol, communication data, etc. A first portion of the radar clutter is analyzed to determine a radar signature of the first portion of the radar clutter. A second portion of the radar clutter can be extracted based on the radar signature of the first portion. Following extraction, any residual signal can be analyzed to retrieve preamble data, etc. The received signal can be based upon a linear frequency modulation (e.g., a chirp modulation) whereby the chirp frequency can be determined and the frequency of transmission of the communication signal can be based accordingly thereon. The duration and/or bandwidth of the communication signal can be a portion of the duration and/or the bandwidth of the radar clutter.

  6. Binaural release from informational masking in a speech identification task

    NASA Astrophysics Data System (ADS)

    Gallun, Frederick J.; Mason, Christine R.; Kidd, Gerald

    2005-09-01

    Binaural release from informational masking (IM) was examined in a speech identification task. Target and masker sentences were processed into mutually exclusive frequency bands, thus limiting energetic masking (EM), and presented over headphones. In a baseline condition, both were presented monotically to the same ear (TmMm). Despite minimal frequency overlap between target and masker, the presence of the masker resulted in reduced performance, or IM. Presenting the target monotically and the masker diotically (TmM0) resulted in a release from IM. Release was also obtained by imposing interaural differences in level (ILDs) and in time (ITDs) on the maskers (TmMILD,TmMITD). Any masker with a perceived lateral position that differed from that of a truly monaural stimulus resulted in a similar amount of release from IM relative to TmMm. For binaural targets and maskers (T0MILD,T0MITD), release was seen whenever ITDs or ILDs differed between target and masker. These results suggest that binaural cues can be very effective in reducing IM. Because mechanisms based on differences in perceived location make predictions that are similar to those of nonlocation-based binaural mechanisms, a variant of the equalization-cancellation model is also considered.

  7. Compressive detection of frequency-hopping spread spectrum signals

    NASA Astrophysics Data System (ADS)

    Liu, Feng; Marcellin, Michael W.; Goodman, Nathan A.; Bilgin, Ali

    2013-05-01

    In this paper, compressive detection strategies for FHSS signals are introduced. Rapid switching of the carrier frequency among many channels using a pseudorandom sequence makes detection of FHSS signals challenging. The conventional approach to detect these signals is to rapidly scan small segments of the spectrum sequentially. However, such a scanner has the inherent risk of never overlapping with the transmitted signal depending on factors such as rate of hopping and scanning. In this paper, we propose compressive detection strategies that sample the full spectrum in a compressive manner. Theory and simulations are presented to illustrate the benefits of the proposed framework.

  8. Auditory target detection in reverberation

    NASA Astrophysics Data System (ADS)

    Zurek, Patrick M.; Freyman, Richard L.; Balakrishnan, Uma

    2004-04-01

    Measurements and theoretical predictions of auditory target detection in simulated reverberant conditions are reported. The target signals were pulsed 13-octave bands of noise and the masker signal was a continuous wideband noise. Target and masker signals were passed through a software simulation of a reverberant room with a rigid sphere modeling a listener's head. The location of the target was fixed while the location of the masker was varied in the simulated room. Degree of reverberation was controlled by varying the uniform acoustic absorption of the simulated room's surfaces. The resulting target and masker signals were presented to the listeners over headphones in monaural-left, monaural-right, or binaural listening modes. Changes in detection performance in the monaural listening modes were largely predictable from the changes in target-to-masker ratio in the target band, but with a few dB of extra masking in reverberation. Binaural detection performance was generally well predicted by applying Durlach's [in Foundations of Modern Auditory Theory (Academic, New York, 1972)] equalization-cancellation theory to the direct-plus-reverberant ear signals. Predictions in all cases were based on a statistical description of room acoustics and on acoustic diffraction by a sphere. The success of these detection models in the present well-controlled reverberant conditions suggests that they can be used to incorporate listening mode and source location as factors in speech-intelligibility predictions.

  9. A function for binaural integration in auditory grouping and segregation in the inferior colliculus.

    PubMed

    Nakamoto, Kyle T; Shackleton, Trevor M; Magezi, David A; Palmer, Alan R

    2015-03-15

    Responses of neurons to binaural, harmonic complex stimuli in urethane-anesthetized guinea pig inferior colliculus (IC) are reported. To assess the binaural integration of harmonicity cues for sound segregation and grouping, responses were measured to harmonic complexes with different fundamental frequencies presented to each ear. Simultaneously gated harmonic stimuli with fundamental frequencies of 125 Hz and 145 Hz were presented to the left and right ears, respectively, and recordings made from 96 neurons with characteristic frequencies >2 kHz in the central nucleus of the IC. Of these units, 70 responded continuously throughout the stimulus and were excited by the stimulus at the contralateral ear. The stimulus at the ipsilateral ear excited (EE: 14%; 10/70), inhibited (EI: 33%; 23/70), or had no significant effect (EO: 53%; 37/70), defined by the effect on firing rate. The neurons phase locked to the temporal envelope at each ear to varying degrees depending on signal level. Many of the cells (predominantly EO) were dominated by the response to the contralateral stimulus. Another group (predominantly EI) synchronized to the contralateral stimulus and were suppressed by the ipsilateral stimulus in a phasic manner. A third group synchronized to the stimuli at both ears (predominantly EE). Finally, a group only responded when the waveform peaks from each ear coincided. We conclude that these groups of neurons represent different "streams" of information but exhibit modifications of the response rather than encoding a feature of the stimulus, like pitch. PMID:25540219

  10. Limitations on Monaural and Binaural Temporal Processing in Bilateral Cochlear Implant Listeners.

    PubMed

    Ihlefeld, Antje; Carlyon, Robert P; Kan, Alan; Churchill, Tyler H; Litovsky, Ruth Y

    2015-10-01

    Monaural rate discrimination and binaural interaural time difference (ITD) discrimination were studied as functions of pulse rate in a group of bilaterally implanted cochlear implant users. Stimuli for the rate discrimination task were pulse trains presented to one electrode, which could be in the apical, middle, or basal part of the array, and in either the left or the right ear. In each two-interval trial, the standard stimulus had a rate of 100, 200, 300, or 500 pulses per second and the signal stimulus had a rate 35% higher. ITD discrimination between pitch-matched electrode pairs was measured for the same standard rates as in the rate discrimination task and with an ITD of +/- 500 μs. Sensitivity (d') on both tasks decreased with increasing rate, as has been reported previously. This study tested the hypothesis that deterioration in performance at high rates occurs for the two tasks due to a common neural basis, specific to the stimulation of each electrode. Results show that ITD scores for different pairs of electrodes correlated with the lower rate discrimination scores for those two electrodes. Statistical analysis, which partialed out overall differences between listeners, electrodes, and rates, supports the hypothesis that monaural and binaural temporal processing limitations are at least partly due to a common mechanism. PMID:26105749

  11. The effect of overlap-masking on binaural reverberant word intelligibility

    NASA Astrophysics Data System (ADS)

    Libbey, Brad; Rogers, Peter H.

    2004-11-01

    Reverberation interferes with the ability to understand speech in rooms. Overlap-masking explains this degradation by assuming reverberant phonemes endure in time and mask subsequent reverberant phonemes. Most listeners benefit from binaural listening when reverberation exists, indicating that the listener's binaural system processes the two channels to reduce the reverberation. This paper investigates the hypothesis that the binaural word intelligibility advantage found in reverberation is a result of binaural overlap-masking release with the reverberation acting as masking noise. The tests utilize phonetically balanced word lists (ANSI-S3.2 1989), that are presented diotically and binaurally with recorded reverberation and reverberation-like noise. A small room, 62 m3, reverberates the words. These are recorded using two microphones without additional noise sources. The reverberation-like noise is a modified form of these recordings and has a similar spectral content. It does not contain binaural localization cues due to a phase randomization procedure. Listening to the reverberant words binaurally improves the intelligibility by 6.0% over diotic listening. The binaural intelligibility advantage for reverberation-like noise is only 2.6%. This indicates that binaural overlap-masking release is insufficient to explain the entire binaural word intelligibility advantage in reverberation. .

  12. A Dynamic Stimulus-Driven Model of Signal Detection

    ERIC Educational Resources Information Center

    Turner, Brandon M.; Van Zandt, Trisha; Brown, Scott

    2011-01-01

    Signal detection theory forms the core of many current models of cognition, including memory, choice, and categorization. However, the classic signal detection model presumes the a priori existence of fixed stimulus representations--usually Gaussian distributions--even when the observer has no experience with the task. Furthermore, the classic…

  13. On the detection of differentially encoded polyphase signals.

    NASA Technical Reports Server (NTRS)

    Lindsey, W. C.

    1972-01-01

    Discussion of the transmission and detection of differentially encoded polyphase signals and of the ambiguity resolution problem which results from suppression of the transmitted carrier. In particular, an analysis is made of the performance of differentially encoded coherent multiple phase-shift keyed (MPSK) systems which reconstruct coherent reference signals by means of generalized Costas or nth-power loops. The performance of such systems is then compared with that of ideal reception of MPSK signals and differentially coherent detection of differentially encoded MPSK signals. Emphasis is placed upon the special cases of quadriphase and octaphase signaling.

  14. Binaural sonar electronic travel aid provides vibrotactile cues for landmark, reflector motion and surface texture classification.

    PubMed

    Kuc, Roman

    2002-10-01

    Electronic travel aids (ETAs) for the blind commonly employ conventional time-of-flight sonars to provide range measurements, but their wide beams prevent accurate determination of object bearing. We describe a binaural sonar that detects objects over a wider bearing interval compared with a single transducer and also determines if the object lies to the left or right of the sonar axis in a robust manner. The sonar employs a pair of Polaroid 6500 ranging modules connected to Polaroid 7000 transducers operating simultaneously in a binaural array configuration. The sonar determines which transducer detects the echo first. An outward vergence angle between the transducers improves the first-echo detection reliability by increasing the delay between the two detected echoes, a consequence of threshold detection. We exploit this left/right detection capability in an ETA that provides vibrotactile feedback. Pager motors mount on both sides of the sonar, possibly worn on the user's wrists. The motor on the same side as the reflecting object vibrates with speed inversely related to range. As the sonar or object moves, vibration patterns provide landmark, motion and texture cues. Orienting the sonar at 45 degrees relative to the travel direction and passing a right-angle corner produces a characteristic vibrational pattern. When pointing the sonar at a moving object, such as a fluttering flag, the motors alternate in a manner to give the user a perception of the object motion. When the sonar translates or rotates to scan a foliage surface, the vibrational patterns are related to the surface scatterer distribution, allowing the user to identify the foliage.

  15. Stimulus configuration determines the detectability of motion signals in noise

    NASA Technical Reports Server (NTRS)

    Verghese, P.; McKee, S. P.; Grzywacz, N. M.

    2000-01-01

    We measured the detectability of moving signal dots in dynamic noise to determine whether local motion signals are preferentially combined along an axis parallel to the direction of motion. Observers were asked to detect a signal composed of three dots moving in a linear trajectory among dynamic noise dots. The signal dots were collinear and equally spaced in a configuration that was either parallel to or perpendicular to their trajectory. The probability of detecting the signal was measured as a function of noise density, over a range of signal dot spacings from 0.5 degrees to 5.0 degrees. At any given noise density, the signal in the parallel configuration was more detectable than that in the perpendicular configuration. Our four observers could tolerate 1.5-2.5 times more noise in the parallel configuration. This improvement is not due merely to temporal summation between consecutive dots in the parallel trajectory. Temporal summation functions measured on our observers indicate that the benefit from spatial coincidence of the dots lasts for no more than 50 ms, whereas the increased detectability of the parallel configuration is observed up to the largest temporal separations tested (210 ms). These results demonstrate that dots arranged parallel to the signal trajectory are more easily detected than those arranged perpendicularly. Moreover, this enhancement points to the existence of visual mechanisms that preferentially organize motion information parallel to the direction of motion.

  16. Collaborative Wideband Compressed Signal Detection in Interplanetary Internet

    NASA Astrophysics Data System (ADS)

    Wang, Yulin; Zhang, Gengxin; Bian, Dongming; Gou, Liang; Zhang, Wei

    2014-07-01

    As the development of autonomous radio in deep space network, it is possible to actualize communication between explorers, aircrafts, rovers and satellites, e.g. from different countries, adopting different signal modes. The first mission to enforce the autonomous radio is to detect signals of the explorer autonomously without disturbing the original communication. This paper develops a collaborative wideband compressed signal detection approach for InterPlaNetary (IPN) Internet where there exist sparse active signals in the deep space environment. Compressed sensing (CS) can be utilized by exploiting the sparsity of IPN Internet communication signal, whose useful frequency support occupies only a small portion of an entirely wide spectrum. An estimate of the signal spectrum can be obtained by using reconstruction algorithms. Against deep space shadowing and channel fading, multiple satellites collaboratively sense and make a final decision according to certain fusion rule to gain spatial diversity. A couple of novel discrete cosine transform (DCT) and walsh-hadamard transform (WHT) based compressed spectrum detection methods are proposed which significantly improve the performance of spectrum recovery and signal detection. Finally, extensive simulation results are presented to show the effectiveness of our proposed collaborative scheme for signal detection in IPN Internet. Compared with the conventional discrete fourier transform (DFT) based method, our DCT and WHT based methods reduce computational complexity, decrease processing time, save energy and enhance probability of detection.

  17. The effect of stimulus bandwidth on binaural loudness summation.

    PubMed

    Shao, Zhiyue; Mo, Fangshuo; Mao, Dongxing

    2015-09-01

    Binaural loudness summation is an important property of the human auditory system. This paper presents an experimental investigation of how binaural loudness summation varies with stimulus bandwidth. Loudness matches were obtained between dichotic stimuli, with interaural level differences (ILDs) of 2-12 dB, and diotic stimuli. The stimuli were noise bands with seven center frequencies and four bandwidths. Results showed that the loudness of dichotic stimuli increased nonlinearly with ILD, the increase being slightly less with broader bandwidths. There was a bandwidth-dependent difference between the listening tests results and the predictions of Moore and Glasberg's [(2007) J. Acoust. Soc. Am. 121, 1604-1612] loudness model. The size of the difference was, however, small. A characteristic function was derived describing how overall loudness depends on stimulus bandwidth and ILD. PMID:26428788

  18. Intelligibility for Binaural Speech with Discarded Low-SNR Speech Components.

    PubMed

    Schoenmaker, Esther; van de Par, Steven

    2016-01-01

    Speech intelligibility in multitalker settings improves when the target speaker is spatially separated from the interfering speakers. A factor that may contribute to this improvement is the improved detectability of target-speech components due to binaural interaction in analogy to the Binaural Masking Level Difference (BMLD). This would allow listeners to hear target speech components within specific time-frequency intervals that have a negative SNR, similar to the improvement in the detectability of a tone in noise when these contain disparate interaural difference cues. To investigate whether these negative-SNR target-speech components indeed contribute to speech intelligibility, a stimulus manipulation was performed where all target components were removed when local SNRs were smaller than a certain criterion value. It can be expected that for sufficiently high criterion values target speech components will be removed that do contribute to speech intelligibility. For spatially separated speakers, assuming that a BMLD-like detection advantage contributes to intelligibility, degradation in intelligibility is expected already at criterion values below 0 dB SNR. However, for collocated speakers it is expected that higher criterion values can be applied without impairing speech intelligibility. Results show that degradation of intelligibility for separated speakers is only seen for criterion values of 0 dB and above, indicating a negligible contribution of a BMLD-like detection advantage in multitalker settings. These results show that the spatial benefit is related to a spatial separation of speech components at positive local SNRs rather than to a BMLD-like detection improvement for speech components at negative local SNRs. PMID:27080648

  19. 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.

  20. Phase coherence adaptive processor for automatic signal detection and identification

    NASA Astrophysics Data System (ADS)

    Wagstaff, Ronald A.

    2006-05-01

    A continuously adapting acoustic signal processor with an automatic detection/decision aid is presented. Its purpose is to preserve the signals of tactical interest, and filter out other signals and noise. It utilizes single sensor or beamformed spectral data and transforms the signal and noise phase angles into "aligned phase angles" (APA). The APA increase the phase temporal coherence of signals and leave the noise incoherent. Coherence thresholds are set, which are representative of the type of source "threat vehicle" and the geographic area or volume in which it is operating. These thresholds separate signals, based on the "quality" of their APA coherence. An example is presented in which signals from a submerged source in the ocean are preserved, while clutter signals from ships and noise are entirely eliminated. Furthermore, the "signals of interest" were identified by the processor's automatic detection aid. Similar performance is expected for air and ground vehicles. The processor's equations are formulated in such a manner that they can be tuned to eliminate noise and exploit signal, based on the "quality" of their APA temporal coherence. The mathematical formulation for this processor is presented, including the method by which the processor continuously self-adapts. Results show nearly complete elimination of noise, with only the selected category of signals remaining, and accompanying enhancements in spectral and spatial resolution. In most cases, the concept of signal-to-noise ratio looses significance, and "adaptive automated /decision aid" is more relevant.

  1. Detecting nonlinear oscillations in broadband signals

    NASA Astrophysics Data System (ADS)

    Vejmelka, Martin; Paluš, Milan

    2009-03-01

    A framework for detecting nonlinear oscillatory activity in broadband time series is presented. First, a narrow-band oscillatory mode is extracted from a broadband background. Second, it is tested whether the extracted mode is significantly different from linearly filtered noise, modeled as a linear stochastic process possibly passed through a static nonlinear transformation. If a nonlinear oscillatory mode is positively detected, it can be further analyzed using nonlinear approaches such as phase synchronization analysis. For linear processes standard approaches, such as the coherence analysis, are more appropriate. The method is illustrated in a numerical example and applied to analyze experimentally obtained human electroencephalogram time series from a sleeping subject.

  2. Wavelet-based detection of transients in biological signals

    NASA Astrophysics Data System (ADS)

    Mzaik, Tahsin; Jagadeesh, Jogikal M.

    1994-10-01

    This paper presents two multiresolution algorithms for detection and separation of mixed signals using the wavelet transform. The first algorithm allows one to design a mother wavelet and its associated wavelet grid that guarantees the separation of signal components if information about the expected minimum signal time and frequency separation of the individual components is known. The second algorithm expands this idea to design two mother wavelets which are then combined to achieve the required separation otherwise impossible with a single wavelet. Potential applications include many biological signals such as ECG, EKG, and retinal signals.

  3. Enzymatic signal amplification of molecular beacons for sensitive DNA detection.

    PubMed

    Li, Jianwei Jeffery; Chu, Yizhuo; Lee, Benjamin Yi-Hung; Xie, Xiaoliang Sunney

    2008-04-01

    Molecular beacons represent a new family of fluorescent probes for nucleic acids, and have found broad applications in recent years due to their unique advantages over traditional probes. Detection of nucleic acids using molecular beacons has been based on hybridization between target molecules and molecular beacons in a 1:1 stoichiometric ratio. The stoichiometric hybridization, however, puts an intrinsic limitation on detection sensitivity, because one target molecule converts only one beacon molecule to its fluorescent form. To increase the detection sensitivity, a conventional strategy has been target amplification through polymerase chain reaction. Instead of target amplification, here we introduce a scheme of signal amplification, nicking enzyme signal amplification, to increase the detection sensitivity of molecular beacons. The mechanism of the signal amplification lies in target-dependent cleavage of molecular beacons by a DNA nicking enzyme, through which one target DNA can open many beacon molecules, giving rise to amplification of fluorescent signal. Our results indicate that one target DNA leads to cleavage of hundreds of beacon molecules, increasing detection sensitivity by nearly three orders of magnitude. We designed two versions of signal amplification. The basic version, though simple, requires that nicking enzyme recognition sequence be present in the target DNA. The extended version allows detection of target of any sequence by incorporating rolling circle amplification. Moreover, the extended version provides one additional level of signal amplification, bringing the detection limit down to tens of femtomolar, nearly five orders of magnitude lower than that of conventional hybridization assay.

  4. ECG Signal Analysis and Arrhythmia Detection using Wavelet Transform

    NASA Astrophysics Data System (ADS)

    Kaur, Inderbir; Rajni, Rajni; Marwaha, Anupma

    2016-06-01

    Electrocardiogram (ECG) is used to record the electrical activity of the heart. The ECG signal being non-stationary in nature, makes the analysis and interpretation of the signal very difficult. Hence accurate analysis of ECG signal with a powerful tool like discrete wavelet transform (DWT) becomes imperative. In this paper, ECG signal is denoised to remove the artifacts and analyzed using Wavelet Transform to detect the QRS complex and arrhythmia. This work is implemented in MATLAB software for MIT/BIH Arrhythmia database and yields the sensitivity of 99.85 %, positive predictivity of 99.92 % and detection error rate of 0.221 % with wavelet transform. It is also inferred that DWT outperforms principle component analysis technique in detection of ECG signal.

  5. Windshear detection radar signal processing studies

    NASA Technical Reports Server (NTRS)

    Baxa, Ernest G., Jr.

    1993-01-01

    This final report briefly summarizes research work at Clemson in the Radar Systems Laboratory under the NASA Langley Research Grant NAG-1-928 in support of the Antenna and Microwave Branch, Guidance and Control Division, program to develop airborne sensor technology for the detection of low altitude windshear. A bibliography of all publications generated by Clemson personnel is included. An appendix provides abstracts of all publications.

  6. Calculating the probability of detecting radio signals from alien civilizations

    NASA Astrophysics Data System (ADS)

    Horvat, Marko

    2006-09-01

    Although it might not be self-evident, it is in fact entirely possible to calculate the probability of detecting alien radio signals by understanding what types of extraterrestrial radio emissions can be expected and what properties these emissions can have. Using the Drake equation as the obvious starting point, and logically identifying and enumerating constraints of interstellar radio communications, may yield the possibility of detecting a genuine alien radio signal.

  7. Optimum Detection Of Slow-Frequency-Hopping Signals

    NASA Technical Reports Server (NTRS)

    Levitt, Barry K.; Cheng, Unjeng

    1994-01-01

    Two papers present theoretical analyses of various schemes for coherent and noncoherent detection of M-ary-frequency-shift-keyed (MFSK) signals with slow frequency hopping. Special attention focused on continuous-phase-modulation (CPM) subset of SFH/MFSK signals, for which frequency modulation such carrier phase remains continuous (albeit unknown) during each hop.

  8. Signal Detection Framework Using Semantic Text Mining Techniques

    ERIC Educational Resources Information Center

    Sudarsan, Sithu D.

    2009-01-01

    Signal detection is a challenging task for regulatory and intelligence agencies. Subject matter experts in those agencies analyze documents, generally containing narrative text in a time bound manner for signals by identification, evaluation and confirmation, leading to follow-up action e.g., recalling a defective product or public advisory for…

  9. The Sensitive Infrared Signal Detection by Sum Frequency Generation

    NASA Technical Reports Server (NTRS)

    Wong, Teh-Hwa; Yu, Jirong; Bai, Yingxin

    2013-01-01

    An up-conversion device that converts 2.05-micron light to 700 nm signal by sum frequency generation using a periodically poled lithium niobate crystal is demonstrated. The achieved 92% up-conversion efficiency paves the path to detect extremely weak 2.05-micron signal with well established silicon avalanche photodiode detector for sensitive lidar applications.

  10. Can arterial spin labeling detect white matter perfusion signal?

    PubMed

    van Osch, Matthias J P; Teeuwisse, Wouter M; van Walderveen, Marianne A A; Hendrikse, Jeroen; Kies, Dennis A; van Buchem, Mark A

    2009-07-01

    Since the invention of arterial spin labeling (ASL) it has been acknowledged that ASL does not allow reliable detection of a white matter (WM) perfusion signal. However, recent developments such as pseudo-continuous labeling and background suppression have improved the quality. The goal of this research was to study the ability of these newer ASL sequences to detect WM perfusion signal. Background suppressed pseudo-continuous ASL was implemented at 3T with multislice 2D readout after 1525 ms. In five volunteers it was shown that 10 min scanning resulted in significant perfusion signal in 70% of WM voxels. Increasing the labeling and delay time did not lead to a higher percentage. In 27 normal volunteers it was found that 35 averages are necessary to detect significant WM signal, but 150 averages are needed to detect signal in the deep WM. Finally, it was shown in a patient with a cerebral arteriovenous malformation that pseudo-continuous ASL enabled the depiction of hypointense WM perfusion signal, although dynamic susceptibility contrast MRI showed that this region was merely showing delayed arrival of contrast agent than hypoperfusion. It can be concluded that, except within the deep WM, ASL is sensitive enough to detect WM perfusion signal and perfusion deficits. PMID:19365865

  11. Waveform Fingerprinting for Efficient Seismic Signal Detection

    NASA Astrophysics Data System (ADS)

    Yoon, C. E.; OReilly, O. J.; Beroza, G. C.

    2013-12-01

    Cross-correlating an earthquake waveform template with continuous waveform data has proven a powerful approach for detecting events missing from earthquake catalogs. If templates do not exist, it is possible to divide the waveform data into short overlapping time windows, then identify window pairs with similar waveforms. Applying these approaches to earthquake monitoring in seismic networks has tremendous potential to improve the completeness of earthquake catalogs, but because effort scales quadratically with time, it rapidly becomes computationally infeasible. We develop a fingerprinting technique to identify similar waveforms, using only a few compact features of the original data. The concept is similar to human fingerprints, which utilize key diagnostic features to identify people uniquely. Analogous audio-fingerprinting approaches have accurately and efficiently found similar audio clips within large databases; example applications include identifying songs and finding copyrighted content within YouTube videos. In order to fingerprint waveforms, we compute a spectrogram of the time series, and segment it into multiple overlapping windows (spectral images). For each spectral image, we apply a wavelet transform, and retain only the sign of the maximum magnitude wavelet coefficients. This procedure retains just the large-scale structure of the data, providing both robustness to noise and significant dimensionality reduction. Each fingerprint is a high-dimensional, sparse, binary data object that can be stored in a database without significant storage costs. Similar fingerprints within the database are efficiently searched using locality-sensitive hashing. We test this technique on waveform data from the Northern California Seismic Network that contains events not detected in the catalog. We show that this algorithm successfully identifies similar waveforms and detects uncataloged low magnitude events in addition to cataloged events, while running to completion

  12. Application of harmonic wavelet to filtering of rockbolt detecting signal

    NASA Astrophysics Data System (ADS)

    Zhao, Yucheng; Liu, Hongyan; Wang, Jiyan; Miao, Xiexing

    2008-11-01

    Harmonic wavelet had explicit functional expression, flexible time-frequency division, simple transforming algorithm and a finer frequency refinement function than the others wavelet. In this paper based on frequency distributing characteristic of nondestructive testing signal from rockbolt supporting system, the discrete harmonic wavelet transforming theory was used to get rid of the lower and higher frequency signal from the initial signal. Meanwhile, the reconstruction algorithm of harmonic wavelet was brought forward to gain the signal without the unnecessary bandwidth signals. Finally, a numerical signal and real signal which can demonstrate superiority of harmonic wavelet in filtering are presented, and the transforming result shows that it would make the system run more precise and stably in the detecting to the quality of rockbolt supporting system.

  13. Multimodal heart beat detection using signal quality indices.

    PubMed

    Johnson, Alistair E W; Behar, Joachim; Andreotti, Fernando; Clifford, Gari D; Oster, Julien

    2015-08-01

    The electrocardiogram (ECG) is a well studied signal from which many clinically relevant parameters can be derived, such as heart rate. A key component in the estimation of these parameters is the accurate detection of the R peak in the QRS complex. While corruption of the ECG by movement artefact or sensor failure can result in poor delineation of the R peak, use of synchronously measured signals could allow for resolution of the R peak even scenarios with poor quality ECG recordings. Robust estimation of R peak locations from multimodal signals facilitates real time monitoring and is likely to reduce false alarms due to inaccurate derived parameters.We propose a method which fuses R peaks detected on the ECG using an energy detector with those detected on the arterial blood pressure (ABP) waveform using the length transform. A signal quality index (SQI) for the two signals is then derived. The ECG SQI is based upon the agreement between two distinct peak detectors. The ABP SQI estimates the blood pressure at various phases in the cardiac cycle and only accepts the signal as good quality if the values are physiologically plausible. Detections from these two signals were merged by selecting the R peak detections from the signal with a higher SQI. The approach presented in this paper was evaluated on datasets provided for the Physionet/Computing in Cardiology Challenge 2014. The algorithm achieved a sensitivity of 95.1% and positive predictive value of 89.3% on an external evaluation set, and achieved a score of 91.5%.The method here demonstrated excellent performance across a variety of signal morphologies collected during clinical practice. Fusion of R peaks from other signals has the potential to provide informed estimates of the R peak location in situations where the ECG is noisy or completely absent. Source code for the algorithm is made available freely online.

  14. Bayesian hierarchical modeling for detecting safety signals in clinical trials.

    PubMed

    Xia, H Amy; Ma, Haijun; Carlin, Bradley P

    2011-09-01

    Detection of safety signals from clinical trial adverse event data is critical in drug development, but carries a challenging statistical multiplicity problem. Bayesian hierarchical mixture modeling is appealing for its ability to borrow strength across subgroups in the data, as well as moderate extreme findings most likely due merely to chance. We implement such a model for subject incidence (Berry and Berry, 2004 ) using a binomial likelihood, and extend it to subject-year adjusted incidence rate estimation under a Poisson likelihood. We use simulation to choose a signal detection threshold, and illustrate some effective graphics for displaying the flagged signals.

  15. A signal detection theory analysis of the placebo effect.

    PubMed

    Allan, Lorraine G; Siegel, Shepard

    2002-12-01

    Some instances of the placebo effect may be understood as a particular type of error made by the patient--a false positive error. False positive errors are common (indeed, frequently encouraged) in medical decision making, both by diagnosticians and by patients, and are the inevitable consequence of concluding that an ambiguous signal (e.g., attenuation of pain, relief of depression) did, or did not, occur. Signal detection theory (SDT) was developed to model errors in the detection of ambiguous signals. The authors use SDT to understand the false positive errors that might be made by patients administered a placebo and termed a placebo effect.

  16. Subsurface Event Detection and Classification Using Wireless Signal Networks

    PubMed Central

    Yoon, Suk-Un; Ghazanfari, Ehsan; Cheng, Liang; Pamukcu, Sibel; Suleiman, Muhannad T.

    2012-01-01

    Subsurface environment sensing and monitoring applications such as detection of water intrusion or a landslide, which could significantly change the physical properties of the host soil, can be accomplished using a novel concept, Wireless Signal Networks (WSiNs). The wireless signal networks take advantage of the variations of radio signal strength on the distributed underground sensor nodes of WSiNs to monitor and characterize the sensed area. To characterize subsurface environments for event detection and classification, this paper provides a detailed list and experimental data of soil properties on how radio propagation is affected by soil properties in subsurface communication environments. Experiments demonstrated that calibrated wireless signal strength variations can be used as indicators to sense changes in the subsurface environment. The concept of WSiNs for the subsurface event detection is evaluated with applications such as detection of water intrusion, relative density change, and relative motion using actual underground sensor nodes. To classify geo-events using the measured signal strength as a main indicator of geo-events, we propose a window-based minimum distance classifier based on Bayesian decision theory. The window-based classifier for wireless signal networks has two steps: event detection and event classification. With the event detection, the window-based classifier classifies geo-events on the event occurring regions that are called a classification window. The proposed window-based classification method is evaluated with a water leakage experiment in which the data has been measured in laboratory experiments. In these experiments, the proposed detection and classification method based on wireless signal network can detect and classify subsurface events. PMID:23202191

  17. Subsurface event detection and classification using Wireless Signal Networks.

    PubMed

    Yoon, Suk-Un; Ghazanfari, Ehsan; Cheng, Liang; Pamukcu, Sibel; Suleiman, Muhannad T

    2012-01-01

    Subsurface environment sensing and monitoring applications such as detection of water intrusion or a landslide, which could significantly change the physical properties of the host soil, can be accomplished using a novel concept, Wireless Signal Networks (WSiNs). The wireless signal networks take advantage of the variations of radio signal strength on the distributed underground sensor nodes of WSiNs to monitor and characterize the sensed area. To characterize subsurface environments for event detection and classification, this paper provides a detailed list and experimental data of soil properties on how radio propagation is affected by soil properties in subsurface communication environments. Experiments demonstrated that calibrated wireless signal strength variations can be used as indicators to sense changes in the subsurface environment. The concept of WSiNs for the subsurface event detection is evaluated with applications such as detection of water intrusion, relative density change, and relative motion using actual underground sensor nodes. To classify geo-events using the measured signal strength as a main indicator of geo-events, we propose a window-based minimum distance classifier based on Bayesian decision theory. The window-based classifier for wireless signal networks has two steps: event detection and event classification. With the event detection, the window-based classifier classifies geo-events on the event occurring regions that are called a classification window. The proposed window-based classification method is evaluated with a water leakage experiment in which the data has been measured in laboratory experiments. In these experiments, the proposed detection and classification method based on wireless signal network can detect and classify subsurface events. PMID:23202191

  18. Detection of buried objects using reflected GNSS signals

    NASA Astrophysics Data System (ADS)

    Notarpietro, Riccardo; De Mattia, Salvatore; Campanella, Maurizio; Pei, Yuekun; Savi, Patrizia

    2014-12-01

    The use of reflected Global Navigation Satellite System (GNSS) signals for sensing the Earth has been growing rapidly in recent years. This technique is founded on the basic principle of detecting GNSS signals after they have been reflected off the Earth's surface and using them to determine the properties of the reflecting surface remotely. This is the so-called GNSS reflectometry (GNSS-R) technique. In this paper, a new application regarding the detection of metallic buried objects is analyzed and it is validated through several experimental campaigns. Although the penetration depth of GNSS signals into the ground is not optimal and depends on the soil moisture, GNSS signals can likely interact approximately with the first 10 cm of the ground and therefore can be reflected back by any metallic object buried on the first terrain layer. A very light and low-cost GNSS receiver prototype based on a software-defined radio approach was developed. This receiver can be used as a payload on board small drones or unmanned aerial systems to detect metallic objects (mines or other explosive devices). A signal processing tool based on an open-loop GNSS signal acquisition strategy was developed. The results of two experiments which show the possibility of using GNSS-R signals to detect buried metallic objects and to provide an estimate of their dimensions are discussed.

  19. Comparing Binaural Pre-processing Strategies III: Speech Intelligibility of Normal-Hearing and Hearing-Impaired Listeners.

    PubMed

    Völker, Christoph; Warzybok, Anna; Ernst, Stephan M A

    2015-01-01

    A comprehensive evaluation of eight signal pre-processing strategies, including directional microphones, coherence filters, single-channel noise reduction, binaural beamformers, and their combinations, was undertaken with normal-hearing (NH) and hearing-impaired (HI) listeners. Speech reception thresholds (SRTs) were measured in three noise scenarios (multitalker babble, cafeteria noise, and single competing talker). Predictions of three common instrumental measures were compared with the general perceptual benefit caused by the algorithms. The individual SRTs measured without pre-processing and individual benefits were objectively estimated using the binaural speech intelligibility model. Ten listeners with NH and 12 HI listeners participated. The participants varied in age and pure-tone threshold levels. Although HI listeners required a better signal-to-noise ratio to obtain 50% intelligibility than listeners with NH, no differences in SRT benefit from the different algorithms were found between the two groups. With the exception of single-channel noise reduction, all algorithms showed an improvement in SRT of between 2.1 dB (in cafeteria noise) and 4.8 dB (in single competing talker condition). Model predictions with binaural speech intelligibility model explained 83% of the measured variance of the individual SRTs in the no pre-processing condition. Regarding the benefit from the algorithms, the instrumental measures were not able to predict the perceptual data in all tested noise conditions. The comparable benefit observed for both groups suggests a possible application of noise reduction schemes for listeners with different hearing status. Although the model can predict the individual SRTs without pre-processing, further development is necessary to predict the benefits obtained from the algorithms at an individual level.

  20. A Multiagent System for Integrated Detection of Pharmacovigilance Signals.

    PubMed

    Koutkias, Vassilis; Jaulent, Marie-Christine

    2016-02-01

    Pharmacovigilance is the scientific discipline that copes with the continuous assessment of the safety profile of marketed drugs. This assessment relies on diverse data sources, which are routinely analysed to identify the so-called "signals", i.e. potential associations between drugs and adverse effects, that are unknown or incompletely documented. Various computational methods have been proposed to support domain experts in signal detection. However, recent comparative studies illustrated that current methods exhibit high false-positive rates, significantly variable performance across different datasets used for analysis and events of interest, but also complementarity in their outcomes. In this regard, in order to reinforce accurate and timely signal detection, we elaborated through an agent-based approach towards systematic, joint exploitation of multiple heterogeneous signal detection methods, data sources and other drug-related resources under a common, integrated framework. The approach relies on a multiagent system operating based on a collaborative agent interaction protocol, aiming to implement a comprehensive workflow that comprises of method selection and execution, as well as outcomes' aggregation, filtering, ranking and annotation. This paper presents the design of the proposed multiagent system, discusses implementation issues and demonstrates the applicability of the proposed solution in an example signal detection scenario. This work constitutes a step towards large-scale, integrated and knowledge-intensive computational signal detection. PMID:26590975

  1. Phase-synchronous detection of coherent and incoherent nonlinear signals

    NASA Astrophysics Data System (ADS)

    Karki, Khadga Jung; Kringle, Loni; Marcus, Andrew H.; Pullerits, Tõnu

    2016-01-01

    The nonlinear optical response of a material system contains detailed information about its electronic structure. Standard approaches to nonlinear spectroscopy often use multiple beams crossed in a sample, and detect the wave vector matched polarization in transmission. Here, we apply a phase-synchronous digital detection scheme using an excitation geometry with two phase-modulated collinear ultrafast pulses. This scheme can be used to efficiently detect nonlinear coherent signals and incoherent signals, such as higher harmonics and multiphoton fluorescence and photocurrent, from various systems including a photocell device. We present theory and experiment to demonstrate that when the phase of each laser pulse is modulated at the frequency {φ }1 and {φ }2, respectively, nonlinear signals can be isolated at the frequencies n({φ }2-{φ }1), where n=0,1,2,\\ldots . This approach holds promise for performing nonlinear spectroscopic measurements under low-signal conditions.

  2. Stochastic resonance with colored noise for neural signal detection.

    PubMed

    Duan, Fabing; Chapeau-Blondeau, François; Abbott, Derek

    2014-01-01

    We analyze signal detection with nonlinear test statistics in the presence of colored noise. In the limits of small signal and weak noise correlation, the optimal test statistic and its performance are derived under general conditions, especially concerning the type of noise. We also analyze, for a threshold nonlinearity-a key component of a neural model, the conditions for noise-enhanced performance, establishing that colored noise is superior to white noise for detection. For a parallel array of nonlinear elements, approximating neurons, we demonstrate even broader conditions allowing noise-enhanced detection, via a form of suprathreshold stochastic resonance.

  3. Detection and Processing Techniques of FECG Signal for Fetal Monitoring

    PubMed Central

    2009-01-01

    Fetal electrocardiogram (FECG) signal contains potentially precise information that could assist clinicians in making more appropriate and timely decisions during labor. The ultimate reason for the interest in FECG signal analysis is in clinical diagnosis and biomedical applications. The extraction and detection of the FECG signal from composite abdominal signals with powerful and advance methodologies are becoming very important requirements in fetal monitoring. The purpose of this review paper is to illustrate the various methodologies and developed algorithms on FECG signal detection and analysis to provide efficient and effective ways of understanding the FECG signal and its nature for fetal monitoring. A comparative study has been carried out to show the performance and accuracy of various methods of FECG signal analysis for fetal monitoring. Finally, this paper further focused some of the hardware implementations using electrical signals for monitoring the fetal heart rate. This paper opens up a passage for researchers, physicians, and end users to advocate an excellent understanding of FECG signal and its analysis procedures for fetal heart rate monitoring system. PMID:19495912

  4. Narrowband signal detection in the SETI field test

    NASA Technical Reports Server (NTRS)

    Cullers, D. Kent; Deans, Stanley R.

    1986-01-01

    Various methods for detecting narrow-band signals are evaluated. The characteristics of synchronized and unsynchronized pulses are examined. Synchronous, square law, regular pulse, and the general form detections are discussed. The CW, single pulse, synchronous, and four pulse detections are analyzed in terms of false alarm rate and threshold relative to average noise power. Techniques for saving memory and retaining sensitivity are described. Consideration is given to nondrifting CW detection, asynchronous pulse detection, interpolative and extrapolative pulse detectors, and finite and infinite pulses.

  5. Application of LSI to signal detection: The deltic DFPCC

    NASA Technical Reports Server (NTRS)

    Gassaway, J. D.; Whelchel, R. J.

    1975-01-01

    The development of the DELTIC DFPCC serial mode signal processor is discussed. The processor is designed to detect in the presence of background noise a signal coded into the zero crossings of the waveform. The unique features of the DELTIC DFPCC include versatility in handling a variety of signals and relative simplicity in implementation. A theoretical performance model is presented which predicts the expected value of the output signal as a function of the input signal to noise ratio. Experimental results obtained with the prototype system, which was breadboarded with LSI, MSI and SSI components, are given. The device was compared with other LSI schemes for signal processing and it was concluded that the DELTIC DFPCC is simpler and in some cases more versatile than other systems. With established LSI technology, low frequency systems applicable to sonar and similar problems are feasible.

  6. Techniques of EMG signal analysis: detection, processing, classification and applications

    PubMed Central

    Hussain, M.S.; Mohd-Yasin, F.

    2006-01-01

    Electromyography (EMG) signals can be used for clinical/biomedical applications, Evolvable Hardware Chip (EHW) development, and modern human computer interaction. EMG signals acquired from muscles require advanced methods for detection, decomposition, processing, and classification. The purpose of this paper is to illustrate the various methodologies and algorithms for EMG signal analysis to provide efficient and effective ways of understanding the signal and its nature. We further point up some of the hardware implementations using EMG focusing on applications related to prosthetic hand control, grasp recognition, and human computer interaction. A comparison study is also given to show performance of various EMG signal analysis methods. This paper provides researchers a good understanding of EMG signal and its analysis procedures. This knowledge will help them develop more powerful, flexible, and efficient applications. PMID:16799694

  7. Signal existence verification (SEV) for GPS low received power signal detection using the time-frequency approach.

    PubMed

    Jan, Shau-Shiun; Sun, Chih-Cheng

    2010-01-01

    The detection of low received power of global positioning system (GPS) signals in the signal acquisition process is an important issue for GPS applications. Improving the miss-detection problem of low received power signal is crucial, especially for urban or indoor environments. This paper proposes a signal existence verification (SEV) process to detect and subsequently verify low received power GPS signals. The SEV process is based on the time-frequency representation of GPS signal, and it can capture the characteristic of GPS signal in the time-frequency plane to enhance the GPS signal acquisition performance. Several simulations and experiments are conducted to show the effectiveness of the proposed method for low received power signal detection. The contribution of this work is that the SEV process is an additional scheme to assist the GPS signal acquisition process in low received power signal detection, without changing the original signal acquisition or tracking algorithms.

  8. Tuning positive feedback for signal detection in noisy dynamic environments.

    PubMed

    Johansson, Anders; Ramsch, Kai; Middendorf, Martin; Sumpter, David J T

    2012-09-21

    Learning from previous actions is a key feature of decision-making. Diverse biological systems, from neuronal assemblies to insect societies, use a combination of positive feedback and forgetting of stored memories to process and respond to input signals. Here we look how these systems deal with a dynamic two-armed bandit problem of detecting a very weak signal in the presence of a high degree of noise. We show that by tuning the form of positive feedback and the decay rate to appropriate values, a single tracking variable can effectively detect dynamic inputs even in the presence of a large degree of noise. In particular, we show that when tuned appropriately a simple positive feedback algorithm is Fisher efficient, in that it can track changes in a signal on a time of order L(h)=(|h|/σ)(-2), where |h| is the magnitude of the signal and σ the magnitude of the noise.

  9. Good Signal Detection Practices: Evidence from IMI PROTECT.

    PubMed

    Wisniewski, Antoni F Z; Bate, Andrew; Bousquet, Cedric; Brueckner, Andreas; Candore, Gianmario; Juhlin, Kristina; Macia-Martinez, Miguel A; Manlik, Katrin; Quarcoo, Naashika; Seabroke, Suzie; Slattery, Jim; Southworth, Harry; Thakrar, Bharat; Tregunno, Phil; Van Holle, Lionel; Kayser, Michael; Norén, G Niklas

    2016-06-01

    Over a period of 5 years, the Innovative Medicines Initiative PROTECT (Pharmacoepidemiological Research on Outcomes of Therapeutics by a European ConsorTium) project has addressed key research questions relevant to the science of safety signal detection. The results of studies conducted into quantitative signal detection in spontaneous reporting, clinical trial and electronic health records databases are summarised and 39 recommendations have been formulated, many based on comparative analyses across a range of databases (e.g. regulatory, pharmaceutical company). The recommendations point to pragmatic steps that those working in the pharmacovigilance community can take to improve signal detection practices, whether in a national or international agency or in a pharmaceutical company setting. PROTECT has also pointed to areas of potentially fruitful future research and some areas where further effort is likely to yield less. PMID:26951233

  10. Photoacoustic imaging with rotational compounding for improved signal detection

    NASA Astrophysics Data System (ADS)

    Forbrich, A.; Heinmiller, A.; Jose, J.; Needles, A.; Hirson, D.

    2015-03-01

    Photoacoustic microscopy with linear array transducers enables fast two-dimensional, cross-sectional photoacoustic imaging. Unfortunately, most ultrasound transducers are only sensitive to a very narrow angular acceptance range and preferentially detect signals along the main axis of the transducer. This often limits photoacoustic microscopy from detecting blood vessels which can extend in any direction. Rotational compounded photoacoustic imaging is introduced to overcome the angular-dependency of detecting acoustic signals with linear array transducers. An integrate system is designed to control the image acquisition using a linear array transducer, a motorized rotational stage, and a motorized lateral stage. Images acquired at multiple angular positions are combined to form a rotational compounded image. We found that the signal-to-noise ratio improved, while the sidelobe and reverberation artifacts were substantially reduced. Furthermore, the rotational compounded images of excised kidneys and hindlimb tumors of mice showed more structural information compared with any single image collected.

  11. Rotational signal detecting apparatus for internal combustion engine

    SciTech Connect

    Koshida, R.

    1988-09-27

    This patent describes a rotational signal detecting apparatus comprising: a housing; a rotor shaft attached to the housing so as to be freely rotatable, the rotor shaft rotating in synchronism with a crankshaft or a cam shaft of an engine; a photoelectric pickup comprising a first rotating portion fixed to the rotor shaft so as to rotate with the rotor shaft as one body, a first fixed portion attached to the housing, the fixed portion having photoelectronic conversion means for outputting a signal varying according to the quantity of incident light varied in synchronism with the rotation of the rotating portion, the first rotating portion and the photoelectric conversion means comprising a first reference signal detecting means for generating a first reference signal each time the crankshaft rotates by a first predetermined angle and a position signal detecting means for generating q position signal each time the crankshaft rotates by a second predetermined angle which is smaller than the first predetermined angle; and an electromagnetic pickup comprising a second rotating portion fixed to the rotor shaft so as to rotate with the rotor shaft as one body and a second fixed portion integrally attached to the housing.

  12. Singularity detection by wavelet approach: application to electrocardiogram signal

    NASA Astrophysics Data System (ADS)

    Jalil, Bushra; Beya, Ouadi; Fauvet, Eric; Laligant, Olivier

    2010-01-01

    In signal processing, the region of abrupt changes contains the most of the useful information about the nature of the signal. The region or the points where these changes occurred are often termed as singular point or singular region. The singularity is considered to be an important character of the signal, as it refers to the discontinuity and interruption present in the signal and the main purpose of the detection of such singular point is to identify the existence, location and size of those singularities. Electrocardiogram (ECG) signal is used to analyze the cardiovascular activity in the human body. However the presence of noise due to several reasons limits the doctor's decision and prevents accurate identification of different pathologies. In this work we attempt to analyze the ECG signal with energy based approach and some heuristic methods to segment and identify different signatures inside the signal. ECG signal has been initially denoised by empirical wavelet shrinkage approach based on Steins Unbiased Risk Estimate (SURE). At the second stage, the ECG signal has been analyzed by Mallat approach based on modulus maximas and Lipschitz exponent computation. The results from both approaches has been discussed and important aspects has been highlighted. In order to evaluate the algorithm, the analysis has been done on MIT-BIH Arrhythmia database; a set of ECG data records sampled at a rate of 360 Hz with 11 bit resolution over a 10mv range. The results have been examined and approved by medical doctors.

  13. Application of signal detection theory to assess optoacoustic imaging systems

    NASA Astrophysics Data System (ADS)

    Lou, Yang; Oraevsky, Alexander; Anastasio, Mark A.

    2016-03-01

    The hybrid nature of optoacoustic tomography (OAT) brings together the advantages of both optical imaging and ultrasound imaging, making it a promising tool for breast cancer imaging. It is advocated in the modern imaging science literature to utilize objective, or task-based, measures of system performance to guide the optimization of hardware design and image reconstruction algorithms. In this work, we investigate this approach to assess the performance of OAT breast imaging systems. In particular, we apply principles from signal detection theory to compute the detectability of a simulated tumor at different depths within a breast, for two different system designs. The signal-to-noise ratio of the test statistic computed by a numerical observer is employed as the task-specific summary measure of system performance. A numerical breast model is employed that contains both slowly varying background and vessel structures as the background model, and superimpose a deterministic signal to emulate a tumor. This study demonstrates how signal detection performance of a numerical observer will vary as a function of signal depth and imaging system characteristics. The described methodology can be employed readily to systematically optimize other OAT imaging systems for tumor detection tasks.

  14. A Duffing oscillator algorithm to detect the weak chromatographic signal.

    PubMed

    Zhang, Wei; Xiang, Bing-Ren

    2007-02-28

    Based on the Duffing equation, a Duffing oscillator algorithm (DOA) to improve the signal-to-noise ratio (SNR) was presented. By simulated and experimental data sets, it was proven that the signal-to-noise ratio (SNR) of the weak signal could be greatly enhanced by this method. Using signal enhancement by DOA, this method extends the SNR of low concentrations of methylbenzene from 2.662 to 29.90 and the method can be used for quantitative analysis of methylbenzene, which are lower than detection limit of an analytical system. The Duffing oscillator algorithm (DOA) might be a promising tool to extend instrumental linear range and to improve the accuracy of trace analysis. The research enlarged the application scope of Duffing equation to chromatographic signal processing.

  15. Universal Collaboration Strategies for Signal Detection: A Sparse Learning Approach

    NASA Astrophysics Data System (ADS)

    Khanduri, Prashant; Kailkhura, Bhavya; Thiagarajan, Jayaraman J.; Varshney, Pramod K.

    2016-10-01

    This paper considers the problem of high dimensional signal detection in a large distributed network whose nodes can collaborate with their one-hop neighboring nodes (spatial collaboration). We assume that only a small subset of nodes communicate with the Fusion Center (FC). We design optimal collaboration strategies which are universal for a class of deterministic signals. By establishing the equivalence between the collaboration strategy design problem and sparse PCA, we solve the problem efficiently and evaluate the impact of collaboration on detection performance.

  16. Application of signal detection theory to perceptual-motor skills.

    PubMed

    Jagacinski, R J; Isaac, P D; Burke, M W

    1977-09-01

    A signal-detection paradigm was utilized to examine subjects' sensitivity to situational and sensory-motor stimuli in predicting motor skill performance. College-level and professional basketball players attempted uncontested shots from assigned positions on the basketball court. Before each shot was released, both the shooter and a passive observer were required to predict whether it would be successful. Signal-detection analysis revealed no evidence for greater sensitivity of the shooter over the passive observer or an idealized statistical predictor using only floor position as a prediction cue. Both shooters and passive observers were too optimistic when strong penalties were imposed for incorrect predictions of success. PMID:23952878

  17. Application of signal detection theory to perceptual-motor skills.

    PubMed

    Jagacinski, R J; Isaac, P D; Burke, M W

    1977-09-01

    A signal-detection paradigm was utilized to examine subjects' sensitivity to situational and sensory-motor stimuli in predicting motor skill performance. College-level and professional basketball players attempted uncontested shots from assigned positions on the basketball court. Before each shot was released, both the shooter and a passive observer were required to predict whether it would be successful. Signal-detection analysis revealed no evidence for greater sensitivity of the shooter over the passive observer or an idealized statistical predictor using only floor position as a prediction cue. Both shooters and passive observers were too optimistic when strong penalties were imposed for incorrect predictions of success.

  18. System and method for detection of dispersed broadband signals

    DOEpatents

    Qian, Shie; Dunham, Mark E.

    1999-06-08

    A system and method for detecting the presence of dispersed broadband signals in real time. The present invention utilizes a bank of matched filters for detecting the received dispersed broadband signals. Each matched filter uses a respective robust time template that has been designed to approximate the dispersed broadband signals of interest, and each time template varies across a spectrum of possible dispersed broadband signal time templates. The received dispersed broadband signal x(t) is received by each of the matched filters, and if one or more matches occurs, then the received data is determined to have signal data of interest. This signal data can then be analyzed and/or transmitted to Earth for analysis, as desired. The system and method of the present invention will prove extremely useful in many fields, including satellite communications, plasma physics, and interstellar research. The varying time templates used in the bank of matched filters are determined as follows. The robust time domain template is assumed to take the form w(t)=A(t)cos{2.phi.(t)}. Since the instantaneous frequency f(t) is known to be equal to the derivative of the phase .phi.(t), the trajectory of a joint time-frequency representation of x(t) is used as an approximation of .phi.'(t).

  19. System and method for detection of dispersed broadband signals

    DOEpatents

    Qian, S.; Dunham, M.E.

    1999-06-08

    A system and method for detecting the presence of dispersed broadband signals in real time are disclosed. The present invention utilizes a bank of matched filters for detecting the received dispersed broadband signals. Each matched filter uses a respective robust time template that has been designed to approximate the dispersed broadband signals of interest, and each time template varies across a spectrum of possible dispersed broadband signal time templates. The received dispersed broadband signal x(t) is received by each of the matched filters, and if one or more matches occurs, then the received data is determined to have signal data of interest. This signal data can then be analyzed and/or transmitted to Earth for analysis, as desired. The system and method of the present invention will prove extremely useful in many fields, including satellite communications, plasma physics, and interstellar research. The varying time templates used in the bank of matched filters are determined as follows. The robust time domain template is assumed to take the form w(t)=A(t)cos[l brace]2[phi](t)[r brace]. Since the instantaneous frequency f(t) is known to be equal to the derivative of the phase [phi](t), the trajectory of a joint time-frequency representation of x(t) is used as an approximation of [phi][prime](t). 10 figs.

  20. Prompt Earthquake Detection based on Transient Gravity Signals.

    NASA Astrophysics Data System (ADS)

    Juhel, K.; Montagner, J. P.; Barsuglia, M.; Ampuero, J. P.; Chassande-Mottin, E.; Harms, J.; Whiting, B. F.; Bernard, P.; Clevede, E.; Lognonne, P. H.

    2015-12-01

    The deformation caused by an earthquake induces changes in the Earth's gravitational field known as coseismic gravity changes, especially during mega-earthquakes. So far, only static gravity changes have been detected, considerably after the end of the rupture. Since gravity changes propagate at the speed of light, a dynamic gravity signal is produced everywhere on Earth during the rupture, even before the arrival of seismic waves. Here we confirm the evidence of this prompt gravity signal. We have analyzed, with a statistical blind method, the data recorded during the 2011 Mw 9.0 Tohoku-oki earthquake by a superconducting gravimeter in the underground Kamioka observatory, about 500 km away from the earthquake centroid. We find that a gravity signal is present before the P wave arrival, with a statistical significance of more than 99%. The signal amplitude is a fraction of μGal, consistent in sign and order-of-magnitude with theoretical predictions. A similar analysis is being conducted on data recorded by the broadband seismometers of the japanese network Fnet. Numerical simulations based on normal-mode method and an analytical model of dynamic gravity signals are used to compute synthetic seismograms, and thus characterize the prompt gravity signal. The robust detection of this prompt gravity signal with instruments more immune to the background seismic noise could, in principle, open new directions in earthquake seismology and overcome limitations of current earthquake early-warning systems imposed by the propagation speed of seismic waves.

  1. Time-Frequency Approach for Stochastic Signal Detection

    SciTech Connect

    Ghosh, Ripul; Akula, Aparna; Kumar, Satish; Sardana, H. K.

    2011-10-20

    The detection of events in a stochastic signal has been a subject of great interest. One of the oldest signal processing technique, Fourier Transform of a signal contains information regarding frequency content, but it cannot resolve the exact onset of changes in the frequency, all temporal information is contained in the phase of the transform. On the other hand, Spectrogram is better able to resolve temporal evolution of frequency content, but has a trade-off in time resolution versus frequency resolution in accordance with the uncertainty principle. Therefore, time-frequency representations are considered for energetic characterisation of the non-stationary signals. Wigner Ville Distribution (WVD) is the most prominent quadratic time-frequency signal representation and used for analysing frequency variations in signals.WVD allows for instantaneous frequency estimation at each data point, for a typical temporal resolution of fractions of a second. This paper through simulations describes the way time frequency models are applied for the detection of event in a stochastic signal.

  2. A signal detection strategy for the SETI All Sky Survey

    NASA Technical Reports Server (NTRS)

    Lawton, W.; Olsen, E. T.; Solomon, J.; Quirk, M. P.

    1985-01-01

    A source detection strategy for the SETI All Sky Survey is described. The method is designed to detect continuous wave (or very narrowband) sources transitting an antenna beam. The short-time spectra of the received signal are accumulated, and candidate extraterrestrial sources are recognized by the recognized by the presence of narrowband power exceeding a threshold function. The threshold function is derived using a Neyman-pearson hypothesis test.

  3. 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.

  4. Binaural interference in bilateral cochlear-implant listeners.

    PubMed

    Best, Virginia; Laback, Bernhard; Majdak, Piotr

    2011-11-01

    This work was aimed at determining whether binaural interference occurs in electric hearing, and if so, whether it occurs as a consequence of perceptual grouping (central explanation) or if it is related to the spread of excitation in the cochlea (peripheral explanation). Six bilateral cochlear-implant listeners completed a series of experiments in which they judged the lateral position of a target pulse train, lateralized via interaural time or level differences, in the presence of an interfering diotic pulse train. The target and interferer were presented at widely separated electrode pairs (one basal and one apical). The results are broadly similar to those reported for acoustic hearing. All listeners but one showed significant binaural interference in at least one of the stimulus conditions. In all cases of interference, a robust recovery was observed when the interferer was presented as part of an ongoing stream of identical pulse trains, suggesting that the interference was at least partly centrally mediated. Overall, the results suggest that both simultaneous and sequential grouping mechanisms operate in electric hearing, at least for stimuli with a wide tonotopic separation. PMID:22087922

  5. Modeling the utility of binaural cues for underwater sound localization.

    PubMed

    Schneider, Jennifer N; Lloyd, David R; Banks, Patchouly N; Mercado, Eduardo

    2014-06-01

    The binaural cues used by terrestrial animals for sound localization in azimuth may not always suffice for accurate sound localization underwater. The purpose of this research was to examine the theoretical limits of interaural timing and level differences available underwater using computational and physical models. A paired-hydrophone system was used to record sounds transmitted underwater and recordings were analyzed using neural networks calibrated to reflect the auditory capabilities of terrestrial mammals. Estimates of source direction based on temporal differences were most accurate for frequencies between 0.5 and 1.75 kHz, with greater resolution toward the midline (2°), and lower resolution toward the periphery (9°). Level cues also changed systematically with source azimuth, even at lower frequencies than expected from theoretical calculations, suggesting that binaural mechanical coupling (e.g., through bone conduction) might, in principle, facilitate underwater sound localization. Overall, the relatively limited ability of the model to estimate source position using temporal and level difference cues underwater suggests that animals such as whales may use additional cues to accurately localize conspecifics and predators at long distances.

  6. Binaural loudness summation for speech presented via earphones and loudspeaker with and without visual cues.

    PubMed

    Epstein, Michael; Florentine, Mary

    2012-05-01

    Preliminary data [M. Epstein and M. Florentine, Ear. Hear. 30, 234-237 (2009)] obtained using speech stimuli from a visually present talker heard via loudspeakers in a sound-attenuating chamber indicate little difference in loudness when listening with one or two ears (i.e., significantly reduced binaural loudness summation, BLS), which is known as "binaural loudness constancy." These data challenge current understanding drawn from laboratory measurements that indicate a tone presented binaurally is louder than the same tone presented monaurally. Twelve normal listeners were presented recorded spondees, monaurally and binaurally across a wide range of levels via earphones and a loudspeaker with and without visual cues. Statistical analyses of binaural-to-monaural ratios of magnitude estimates indicate that the amount of BLS is significantly less for speech presented via a loudspeaker with visual cues than for stimuli with any other combination of test parameters (i.e., speech presented via earphones or a loudspeaker without visual cues, and speech presented via earphones with visual cues). These results indicate that the loudness of a visually present talker in daily environments is little affected by switching between binaural and monaural listening. This supports the phenomenon of binaural loudness constancy and underscores the importance of ecological validity in loudness research.

  7. Safety signal detection: the relevance of literature review.

    PubMed

    Pontes, Helena; Clément, Mallorie; Rollason, Victoria

    2014-07-01

    Adverse drug reactions (ADRs) represent an important risk for patients and have a significant economic impact on health systems. ADRs are the fifth most common cause of hospital death, with a burden estimated at 197,000 deaths per year in the EU. This has a societal cost of 79 billion per year. Because of this strong impact in public health, regulatory authorities (RAs) worldwide are implementing new pharmacovigilance legislation to promote and protect public health by reducing the burden of ADRs through the detection of safety signals. Although, traditionally, signal detection activities have mainly been performed based on spontaneous reporting from healthcare professionals and national health RAs, the new pharmacovigilance legislation underlines the relevance of other sources of information (such as scientific literature) for the evaluation of the benefit-risk balance of a certain product. This review aims to highlight the relevance of periodic scientific literature screening in the safety signal detection process. The authors present four practical examples where a safety signal that was detected from a literature report had an impact on the lifecycle of a drug. In addition, based on practical experience of the screening of medical and scientific literature for safety purposes, this article analyses the requirements of the new pharmacovigilance guidelines on literature screening and highlights the need for the implementation of a literature review procedure and the main challenges encountered when performing literature screening for safety aspects.

  8. Signal processing techniques for clutter filtering and wind shear detection

    NASA Technical Reports Server (NTRS)

    Baxa, Ernest G., Jr.; Deshpande, Manohar D

    1991-01-01

    An extended Prony algorithm applicable to signal processing techniques for clutter filtering and windshear detection is discussed. The algorithm is based upon modelling the radar return as a time series, and appears to offer potential for improving hazard factor estimates in the presence of strong clutter returns.

  9. Safety signal detection: the relevance of literature review.

    PubMed

    Pontes, Helena; Clément, Mallorie; Rollason, Victoria

    2014-07-01

    Adverse drug reactions (ADRs) represent an important risk for patients and have a significant economic impact on health systems. ADRs are the fifth most common cause of hospital death, with a burden estimated at 197,000 deaths per year in the EU. This has a societal cost of 79 billion per year. Because of this strong impact in public health, regulatory authorities (RAs) worldwide are implementing new pharmacovigilance legislation to promote and protect public health by reducing the burden of ADRs through the detection of safety signals. Although, traditionally, signal detection activities have mainly been performed based on spontaneous reporting from healthcare professionals and national health RAs, the new pharmacovigilance legislation underlines the relevance of other sources of information (such as scientific literature) for the evaluation of the benefit-risk balance of a certain product. This review aims to highlight the relevance of periodic scientific literature screening in the safety signal detection process. The authors present four practical examples where a safety signal that was detected from a literature report had an impact on the lifecycle of a drug. In addition, based on practical experience of the screening of medical and scientific literature for safety purposes, this article analyses the requirements of the new pharmacovigilance guidelines on literature screening and highlights the need for the implementation of a literature review procedure and the main challenges encountered when performing literature screening for safety aspects. PMID:24895178

  10. Detection of visual signals by rats: A computational model

    EPA Science Inventory

    We applied a neural network model of classical conditioning proposed by Schmajuk, Lam, and Gray (1996) to visual signal detection and discrimination tasks designed to assess sustained attention in rats (Bushnell, 1999). The model describes the animals’ expectation of receiving fo...

  11. Coherent stochastic oscillations enhance signal detection in spiking neurons.

    PubMed

    Engel, Tatiana A; Helbig, Brian; Russell, David F; Schimansky-Geier, Lutz; Neiman, Alexander B

    2009-08-01

    We study the effect of noisy oscillatory input on the signal discrimination by spontaneously firing neurons. Using analytically tractable model, we contrast signal detection in two situations: (i) when the neuron is driven by coherent oscillations and (ii) when the coherence of oscillations is destroyed. Analytical calculations revealed a region in the parameter space of the model where oscillations act to reduce the variability of neuronal firing and to enhance the discriminability of weak signals. These analytical results are employed to unveil a possible role of coherent oscillations in peripheral electrosensory system of paddlefish in improvement of detection of weak stimuli. The proposed mechanism may be relevant to a wide range of phenomena involving coherently driven oscillators.

  12. Application of signal detection theory to error detection in ballistic motor skills.

    PubMed

    Rubin, W M

    1978-05-01

    Signal detection procedures were used to measure subjects' ability to detect errors in performance as they tried to hit a target in a ballistic motor task, since current methods were found to have several important shortcomings. Two tasks were used; one involved moving a slide 24.1 cm in 150 msec (temporal target), and the other involved rolling a ball at a visible target (spatial target). Subjects in both tasks were poor at detecting errors. Variability in the perceptual processes, measured by signal detection proceudres, was found to be about twice as much as that in the motor processes, measured by calculating variable error. This finding was inconsistent with a strictly closed-loop model of motor skills. Signal detection theory was also able to fill a gap in present theories of motor learning by explaining why some of the subjects in this experiment were able to detect errors better in the absence of knowledge of results.

  13. Automatic detection of service initiation signals used in bars.

    PubMed

    Loth, Sebastian; Huth, Kerstin; De Ruiter, Jan P

    2013-01-01

    Recognizing the intention of others is important in all social interactions, especially in the service domain. Enabling a bartending robot to serve customers is particularly challenging as the system has to recognize the social signals produced by customers and respond appropriately. Detecting whether a customer would like to order is essential for the service encounter to succeed. This detection is particularly challenging in a noisy environment with multiple customers. Thus, a bartending robot has to be able to distinguish between customers intending to order, chatting with friends or just passing by. In order to study which signals customers use to initiate a service interaction in a bar, we recorded real-life customer-staff interactions in several German bars. These recordings were used to generate initial hypotheses about the signals customers produce when bidding for the attention of bar staff. Two experiments using snapshots and short video sequences then tested the validity of these hypothesized candidate signals. The results revealed that bar staff responded to a set of two non-verbal signals: first, customers position themselves directly at the bar counter and, secondly, they look at a member of staff. Both signals were necessary and, when occurring together, sufficient. The participants also showed a strong agreement about when these cues occurred in the videos. Finally, a signal detection analysis revealed that ignoring a potential order is deemed worse than erroneously inviting customers to order. We conclude that (a) these two easily recognizable actions are sufficient for recognizing the intention of customers to initiate a service interaction, but other actions such as gestures and speech were not necessary, and (b) the use of reaction time experiments using natural materials is feasible and provides ecologically valid results.

  14. Signal dependent degradation in noise performance of optimum detectors for multiple signal detection

    NASA Astrophysics Data System (ADS)

    Mahalanobis, Abhijit

    1991-02-01

    The detection of multiple signals in the presence of additive noise is addressed, and finite impulse response (FIR) filters are treated as arrays (or vectors) to facilitate mathematical manipulations. The detection of multiple (more than two) signals in the presence of arbitrary additive noise using a single linear time-invariant (LTI) processor requires the synthesis of generalized filters. A set of N representative views that are sufficiently descriptive of the object are chosen for determining the generalized filter coefficients. These representative images are referred to as the training vectors. The training vectors provide information about the shape and structure of the objects to be classified, and their selection is crucial to the distortion sensitivity of the generalized filter. Each vector in the training set (i.e., the set of images used for filter synthesis) is treated as a signal to be detected and classified using the generalized filter. The problem is to find the filter coefficients such that the output is (1) indicative of the class of the input image, (2) tolerant to additive input noise, and (3) invariant to image distortions. The filter synthesis procedure is reviewed. Degradation in processor performance and the rise in output variance as the number of signals to be detected increases are discussed. It is shown that the variance is a nondecreasing function of the number of signals. Recursive expressions for the exact output variance and incremental changes in variance are derived.

  15. Signal processing techniques for atrial fibrillation source detection.

    PubMed

    Ambadkar, Minal; Leonelli, Fabio M; Sankar, Ravi

    2014-01-01

    In clinical practice, Atrial Fibrillation (AF) is the most common and critical cardiac arrhythmia encountered. The treatment that can ensure permanent AF removal is catheter ablation, where cardiologists destroy the affected cardiac muscle cells with RF or Laser. In this procedure it is necessary to know exactly from which part of the heart AF triggers are originated. Various signal processing algorithms provide a strong tool to track AF sources. This study proposes, signal processing techniques that can be exploited for characterization, analysis and source detection of AF signals. These algorithms are implemented on Electrocardiogram (ECG) and intracardiac signals which contain important information that allows the analysis of anatomic and physiologic aspects of the whole cardiac muscle. PMID:25570578

  16. Signal processing techniques for atrial fibrillation source detection.

    PubMed

    Ambadkar, Minal; Leonelli, Fabio M; Sankar, Ravi

    2014-01-01

    In clinical practice, Atrial Fibrillation (AF) is the most common and critical cardiac arrhythmia encountered. The treatment that can ensure permanent AF removal is catheter ablation, where cardiologists destroy the affected cardiac muscle cells with RF or Laser. In this procedure it is necessary to know exactly from which part of the heart AF triggers are originated. Various signal processing algorithms provide a strong tool to track AF sources. This study proposes, signal processing techniques that can be exploited for characterization, analysis and source detection of AF signals. These algorithms are implemented on Electrocardiogram (ECG) and intracardiac signals which contain important information that allows the analysis of anatomic and physiologic aspects of the whole cardiac muscle.

  17. Evaluation of Speech Intelligibility and Sound Localization Abilities with Hearing Aids Using Binaural Wireless Technology.

    PubMed

    Ibrahim, Iman; Parsa, Vijay; Macpherson, Ewan; Cheesman, Margaret

    2013-01-01

    Wireless synchronization of the digital signal processing (DSP) features between two hearing aids in a bilateral hearing aid fitting is a fairly new technology. This technology is expected to preserve the differences in time and intensity between the two ears by co-ordinating the bilateral DSP features such as multichannel compression, noise reduction, and adaptive directionality. The purpose of this study was to evaluate the benefits of wireless communication as implemented in two commercially available hearing aids. More specifically, this study measured speech intelligibility and sound localization abilities of normal hearing and hearing impaired listeners using bilateral hearing aids with wireless synchronization of multichannel Wide Dynamic Range Compression (WDRC). Twenty subjects participated; 8 had normal hearing and 12 had bilaterally symmetrical sensorineural hearing loss. Each individual completed the Hearing in Noise Test (HINT) and a sound localization test with two types of stimuli. No specific benefit from wireless WDRC synchronization was observed for the HINT; however, hearing impaired listeners had better localization with the wireless synchronization. Binaural wireless technology in hearing aids may improve localization abilities although the possible effect appears to be small at the initial fitting. With adaptation, the hearing aids with synchronized signal processing may lead to an improvement in localization and speech intelligibility. Further research is required to demonstrate the effect of adaptation to the hearing aids with synchronized signal processing on different aspects of auditory performance.

  18. Evaluation of Speech Intelligibility and Sound Localization Abilities with Hearing Aids Using Binaural Wireless Technology

    PubMed Central

    Ibrahim, Iman; Parsa, Vijay; Macpherson, Ewan; Cheesman, Margaret

    2012-01-01

    Wireless synchronization of the digital signal processing (DSP) features between two hearing aids in a bilateral hearing aid fitting is a fairly new technology. This technology is expected to preserve the differences in time and intensity between the two ears by co-ordinating the bilateral DSP features such as multichannel compression, noise reduction, and adaptive directionality. The purpose of this study was to evaluate the benefits of wireless communication as implemented in two commercially available hearing aids. More specifically, this study measured speech intelligibility and sound localization abilities of normal hearing and hearing impaired listeners using bilateral hearing aids with wireless synchronization of multichannel Wide Dynamic Range Compression (WDRC). Twenty subjects participated; 8 had normal hearing and 12 had bilaterally symmetrical sensorineural hearing loss. Each individual completed the Hearing in Noise Test (HINT) and a sound localization test with two types of stimuli. No specific benefit from wireless WDRC synchronization was observed for the HINT; however, hearing impaired listeners had better localization with the wireless synchronization. Binaural wireless technology in hearing aids may improve localization abilities although the possible effect appears to be small at the initial fitting. With adaptation, the hearing aids with synchronized signal processing may lead to an improvement in localization and speech intelligibility. Further research is required to demonstrate the effect of adaptation to the hearing aids with synchronized signal processing on different aspects of auditory performance. PMID:26557339

  19. A Binaural Steering Beamformer System for Enhancing a Moving Speech Source.

    PubMed

    Adiloğlu, Kamil; Kayser, Hendrik; Baumgärtel, Regina M; Rennebeck, Sanja; Dietz, Mathias; Hohmann, Volker

    2015-01-01

    In many daily life communication situations, several sound sources are simultaneously active. While normal-hearing listeners can easily distinguish the target sound source from interfering sound sources-as long as target and interferers are spatially or spectrally separated-and concentrate on the target, hearing-impaired listeners and cochlear implant users have difficulties in making such a distinction. In this article, we propose a binaural approach composed of a spatial filter controlled by a direction-of-arrival estimator to track and enhance a moving target sound. This approach was implemented on a real-time signal processing platform enabling experiments with test subjects in situ. To evaluate the proposed method, a data set of sound signals with a single moving sound source in an anechoic diffuse noise environment was generated using virtual acoustics. The proposed steering method was compared with a fixed (nonsteering) method that enhances sound from the frontal direction in an objective evaluation and subjective experiments using this database. In both cases, the obtained results indicated a significant improvement in speech intelligibility and quality compared with the unprocessed signal. Furthermore, the proposed method outperformed the nonsteering method. PMID:26721924

  20. A Binaural Steering Beamformer System for Enhancing a Moving Speech Source

    PubMed Central

    Kayser, Hendrik; Baumgärtel, Regina M.; Rennebeck, Sanja; Dietz, Mathias; Hohmann, Volker

    2015-01-01

    In many daily life communication situations, several sound sources are simultaneously active. While normal-hearing listeners can easily distinguish the target sound source from interfering sound sources—as long as target and interferers are spatially or spectrally separated—and concentrate on the target, hearing-impaired listeners and cochlear implant users have difficulties in making such a distinction. In this article, we propose a binaural approach composed of a spatial filter controlled by a direction-of-arrival estimator to track and enhance a moving target sound. This approach was implemented on a real-time signal processing platform enabling experiments with test subjects in situ. To evaluate the proposed method, a data set of sound signals with a single moving sound source in an anechoic diffuse noise environment was generated using virtual acoustics. The proposed steering method was compared with a fixed (nonsteering) method that enhances sound from the frontal direction in an objective evaluation and subjective experiments using this database. In both cases, the obtained results indicated a significant improvement in speech intelligibility and quality compared with the unprocessed signal. Furthermore, the proposed method outperformed the nonsteering method. PMID:26721924

  1. Similarity-Based Modeling Applied to Signal Detection in Pharmacovigilance

    PubMed Central

    Vilar, S; Ryan, P B; Madigan, D; Stang, P E; Schuemie, M J; Friedman, C; Tatonetti, N P; Hripcsak, G

    2014-01-01

    One of the main objectives in pharmacovigilance is the detection of adverse drug events (ADEs) through mining of healthcare databases, such as electronic health records or administrative claims data. Although different approaches have been shown to be of great value, research is still focusing on the enhancement of signal detection to gain efficiency in further assessment and follow-up. We applied similarity-based modeling techniques, using 2D and 3D molecular structure, ADE, target, and ATC (anatomical therapeutic chemical) similarity measures, to the candidate associations selected previously in a medication-wide association study for four ADE outcomes. Our results showed an improvement in the precision when we ranked the subset of ADE candidates using similarity scorings. This method is simple, useful to strengthen or prioritize signals generated from healthcare databases, and facilitates ADE detection through the identification of the most similar drugs for which ADE information is available. PMID:25250527

  2. Threshold detection in generalized non-additive signals and noise

    SciTech Connect

    Middleton, D., LLNL

    1997-12-22

    The classical theory of optimum (binary-on-off) threshold detection for additive signals and generalized (i.e. nongaussian) noise is extended to the canonical nonadditive threshold situation. In the important (and usual) applications where the noise is sampled independently, a canonical threshold optimum theory is outlined here, which is found formally to parallel the earlier additive theory, including the critical properties of locally optimum Bayes detection algorithms, which are asymptotically normal and optimum as well. The important Class A clutter model provides an explicit example of optimal threshold envelope detection, for the non-additive cases of signal and noise. Various extensions are noted in the concluding section, as are selected references.

  3. Detection of possible burst transmissions in a dense signal environment

    NASA Astrophysics Data System (ADS)

    Gustavsson, R.

    1993-12-01

    The report presents an algorithm for detection of possible narrowband burst transmissions in the HF band. The algorithm searches a time-frequency matrix containing 10 seconds of magnitude spectrums ranging over 250 kHz momentary bandwidth and is to be used as a preselection to an automatic classifier. The detection algorithm uses, among other things, a two dimensional convolution and analysis of the power spectrums of narrowband signals to extract continuous transmissions with durations of 0.5 to 4 seconds and bandwidths ranging from 100 to 3000 Hz. Initial tests using simulated burst transmissions indicate that the signal to interference ratio should be from 12 to 23 dB (depending on the duration of the burst transmission) to ensure a probability of detection of 50%. The frequency of alarms due to ordinary shortwave traffic is approximately one per second over 250 kHz momentary bandwidth.

  4. Separating Decision and Encoding Noise in Signal Detection Tasks

    PubMed Central

    Cabrera, Carlos Alexander; Lu, Zhong-Lin; Dosher, Barbara Anne

    2015-01-01

    In this paper we develop an extension to the Signal Detection Theory (SDT) framework to separately estimate internal noise arising from representational and decision processes. Our approach constrains SDT models with decision noise by combining a multi-pass external noise paradigm with confidence rating responses. In a simulation study we present evidence that representation and decision noise can be separately estimated over a range of representative underlying representational and decision noise level configurations. These results also hold across a number of decision rules and show resilience to rule miss-specification. The new theoretical framework is applied to a visual detection confidence-rating task with three and five response categories. This study compliments and extends the recent efforts of researchers (Benjamin, Diaz, & Wee, 2009; Mueller & Weidemann, 2008; Rosner & Kochanski, 2009, Kellen, Klauer, & Singmann, 2012) to separate and quantify underlying sources of response variability in signal detection tasks. PMID:26120907

  5. Cross Psi(B)-energy operator-based signal detection.

    PubMed

    Boudraa, Abdel-Ouahab; Cexus, Jean-Christophe; Abed-Meraim, Karim

    2008-06-01

    In this paper, two methods for signal detection and time-delay estimation based on the cross Psi(B)-energy operator are proposed. These methods are well suited for mono-component AM-FM signals. The Psi(B) energy operator measures how much one signal is present in another one. The peak of the Psi(B) operator corresponds to the maximum of interaction between the two signals. Compared to the cross-correlation function, the Psi(B) operator includes temporal information and relative changes of the signal which are reflected in its first and second derivatives. The discrete version of the continuous-time form of the Psi(B) operator, which is used in its implementation, is presented. The methods are illustrated on synthetic and real signals and the results compared to those of the matched filter and the cross correlation. The real signals correspond to impulse responses of buried objects obtained by active sonar in iso-speed single path environments. PMID:18537379

  6. Cross Psi(B)-energy operator-based signal detection.

    PubMed

    Boudraa, Abdel-Ouahab; Cexus, Jean-Christophe; Abed-Meraim, Karim

    2008-06-01

    In this paper, two methods for signal detection and time-delay estimation based on the cross Psi(B)-energy operator are proposed. These methods are well suited for mono-component AM-FM signals. The Psi(B) energy operator measures how much one signal is present in another one. The peak of the Psi(B) operator corresponds to the maximum of interaction between the two signals. Compared to the cross-correlation function, the Psi(B) operator includes temporal information and relative changes of the signal which are reflected in its first and second derivatives. The discrete version of the continuous-time form of the Psi(B) operator, which is used in its implementation, is presented. The methods are illustrated on synthetic and real signals and the results compared to those of the matched filter and the cross correlation. The real signals correspond to impulse responses of buried objects obtained by active sonar in iso-speed single path environments.

  7. Weak signal detection using multiscale morphology in microseismic monitoring

    NASA Astrophysics Data System (ADS)

    Li, Huijian; Wang, Runqiu; Cao, Siyuan; Chen, Yangkang; Tian, Nan; Chen, Xiaoqing

    2016-10-01

    Microseismic events caused by hydraulic fracturing are usually very weak. The magnitude range of microseismic signals is usually from - 3 to 1 Mw. Processing techniques such as band-pass filtering, are widely adopted to improve the signal-to-noise (S/N) ratio of microseismic data, while with a degradation of signal quality. We propose a multi-scale morphological method to detect weak micro-seismic signals. This approach decomposes data set into multi-scale components based on the mathematical morphology theory using structuring element that is similar to the wavelet basis in the well-known wavelet decomposition. The method can help us obtain more information by detecting more waves, like P-wave, S-wave and their reflections, which can be much more valuable in processing and interpretation of microseismic data during microseismic monitoring. The proposed approach is not amplitude preserving and not mathematically reversible. It can offer enhancement of arrivals for picking (and thus can subsequently offer benefits for event detection and location) but at the expense of estimates of magnitude or moment-tensor inversion.

  8. Heart beat detection in multimodal data using automatic relevant signal detection.

    PubMed

    De Cooman, Thomas; Goovaerts, Griet; Varon, Carolina; Widjaja, Devy; Willemen, Tim; Van Huffel, Sabine

    2015-08-01

    Accurate R peak detection in the electrocardiogram (ECG) is a well-known and highly explored problem in biomedical signal processing. Although a lot of progress has been made in this area, current methods are still insufficient in the presence of extreme noise and/or artifacts such as loose electrodes. Often, however, not only the ECG is recorded, but multiple signals are simultaneously acquired from the patient. Several of these signals, such as blood pressure, can help to improve the heart beat detection. These signals of interest can be detected automatically by analyzing their power spectral density or by using the available signal type identifiers. Individual peaks from the signals of interest are combined using majority voting, heart beat location estimation and Hjorth's mobility of the resulting RR intervals. Both multimodal algorithms showed significant increases in performance of up to 8.65% for noisy multimodal datasets compared to when only the ECG signal is used. A maximal performance of 90.02% was obtained on the hidden test set of the Physionet/Computing in Cardiology Challenge 2014: Robust Detection of Heart Beats in Multimodal Data.

  9. Signal processing for passive detection and classification of underwater acoustic signals

    NASA Astrophysics Data System (ADS)

    Chung, Kil Woo

    2011-12-01

    This dissertation examines signal processing for passive detection, classification and tracking of underwater acoustic signals for improving port security and the security of coastal and offshore operations. First, we consider the problem of passive acoustic detection of a diver in a shallow water environment. A frequency-domain multi-band matched-filter approach to swimmer detection is presented. The idea is to break the frequency contents of the hydrophone signals into multiple narrow frequency bands, followed by time averaged (about half of a second) energy calculation over each band. Then, spectra composed of such energy samples over the chosen frequency bands are correlated to form a decision variable. The frequency bands with highest Signal/Noise ratio are used for detection. The performance of the proposed approach is demonstrated for experimental data collected for a diver in the Hudson River. We also propose a new referenceless frequency-domain multi-band detector which, unlike other reference-based detectors, does not require a diver specific signature. Instead, our detector matches to a general feature of the diver spectrum in the high frequency range: the spectrum is roughly periodic in time and approximately flat when the diver exhales. The performance of the proposed approach is demonstrated by using experimental data collected from the Hudson River. Moreover, we present detection, classification and tracking of small vessel signals. Hydroacoustic sensors can be applied for the detection of noise generated by vessels, and this noise can be used for vessel detection, classification and tracking. This dissertation presents recent improvements aimed at the measurement and separation of ship DEMON (Detection of Envelope Modulation on Noise) acoustic signatures in busy harbor conditions. Ship signature measurements were conducted in the Hudson River and NY Harbor. The DEMON spectra demonstrated much better temporal stability compared with the full ship

  10. Deriving content-specific measures of room acoustic perception using a binaural, nonlinear auditory model.

    PubMed

    van Dorp Schuitman, Jasper; de Vries, Diemer; Lindau, Alexander

    2013-03-01

    Acousticians generally assess the acoustic qualities of a concert hall or any other room using impulse response-based measures such as the reverberation time, clarity index, and others. These parameters are used to predict perceptual attributes related to the acoustic qualities of the room. Various studies show that these physical measures are not able to predict the related perceptual attributes sufficiently well under all circumstances. In particular, it has been shown that physical measures are dependent on the state of occupation, are prone to exaggerated spatial fluctuation, and suffer from lacking discrimination regarding the kind of acoustic stimulus being presented. Accordingly, this paper proposes a method for the derivation of signal-based measures aiming at predicting aspects of room acoustic perception from content specific signal representations produced by a binaural, nonlinear model of the human auditory system. Listening tests were performed to test the proposed auditory parameters for both speech and music. The results look promising; the parameters correlate with their corresponding perceptual attributes in most cases. PMID:23464027

  11. Fault detection and bypass in a sequence information signal processor

    NASA Technical Reports Server (NTRS)

    Peterson, John C. (Inventor); Chow, Edward T. (Inventor)

    1992-01-01

    The invention comprises a plurality of scan registers, each such register respectively associated with a processor element; an on-chip comparator, encoder and fault bypass register. Each scan register generates a unitary signal the logic state of which depends on the correctness of the input from the previous processor in the systolic array. These unitary signals are input to a common comparator which generates an output indicating whether or not an error has occurred. These unitary signals are also input to an encoder which identifies the location of any fault detected so that an appropriate multiplexer can be switched to bypass the faulty processor element. Input scan data can be readily programmed to fully exercise all of the processor elements so that no fault can remain undetected.

  12. Magnetic resonance microwave absorption imaging: Feasibility of signal detection

    PubMed Central

    Xie, Bin; Weaver, John B.; Meaney, Paul M.; Paulsen, Keith D.

    2009-01-01

    Purpose: Magnetic resonance (MR) technique was used to detect small displacements induced by localized absorption of pulsed 434 MHz microwave power as a potential method for tumor detection. Methods: Phase contrast subtraction was used to separate the phase change due to motion from thermoelastic expansion from other contributions to phase variation such as the bulk temperature rise of the medium and phase offsets from the MR scanner itself. A simple set of experiments was performed where the motion was constrained to be one dimensional which provided controls on the data acquisition and motion extraction procedures. Specifically, the MR-detected motion signal was isolated by altering the direction of the microwave-induced motion and sampling the response with motion encoding gradients in all three directions when the microwave power was turned on and turned off. Results: Successful signal detection, as evidenced by the recording of a systematic alternating (zigzag) phase pattern, occurred only when the motion encoding was in parallel with either the vertical or horizontal direction of the microwave-induced motion on both 10 and 4 mm spatial scales. Conclusions: These results demonstrate, for the first time, that motion associated with thermoelastic expansion from the absorption of pulsed microwave power can be detected with MR. PMID:19994529

  13. Detecting a periodic signal in the terrestrial cratering record

    NASA Technical Reports Server (NTRS)

    Grieve, Richard A. F.; Rupert, James D.; Goodacre, Alan K.; Sharpton, Virgil L.

    1988-01-01

    A time-series analysis of model periodic data, where the period and phase are known, has been performed in order to investigate whether a significant period can be detected consistently from a mix of random and periodic impacts. Special attention is given to the effect of age uncertainties and random ages in the detection of a periodic signal. An equivalent analysis is performed with observed data on crater ages and compared with the model data, and the effects of the temporal distribution of crater ages on the results from the time-series analysis are studied. Evidence for a consistent 30-m.y. period is found to be weak.

  14. Characterization of escape times of Josephson junctions for signal detection.

    PubMed

    Addesso, Paolo; Filatrella, Giovanni; Pierro, Vincenzo

    2012-01-01

    The measurement of the escape time of a Josephson junction might be used to detect the presence of a sinusoidal signal embedded in noise when use of standard signal processing tools can be prohibitive due to the extreme weakness of the source or to the huge amount of data. In this paper we show that the prescriptions for the experimental setup and some physical behaviors depend on the detection strategy. More specifically, by exploitation of the sample mean of escape times to perform detection, two resonant regions are identified. At low frequencies there is a stochastic resonance or activation phenomenon, while near the plasma frequency a geometric resonance appears. Furthermore, detection performance in the geometric resonance region is maximized at the prescribed value of the bias current. The naive sample mean detector is outperformed, in terms of error probability, by the optimal likelihood ratio test. The latter exhibits only geometric resonance, showing monotonically increasing performance as the bias current approaches the junction critical current. In this regime the escape times are vanishingly small and therefore performance is essentially limited by measurement electronics. The behavior of the likelihood ratio and sample mean detector for different values of incoming signal to noise ratio is discussed, and a relationship with the error probability is found. Detectors based on the likelihood ratio test could be employed also to estimate unknown parameters in the applied input signal. As a prototypical example we study the phase estimation problem of a sinusoidal current, which is accomplished by using the filter bank approach. Finally we show that for a physically feasible detector the performances are found to be very close to the Cramer-Rao theoretical bound. Applications might be found, for example, in some astronomical detection problems (where the all-sky gravitational and/or radio wave search for pulsars requires the analysis of nearly sinusoidal

  15. Characterization of escape times of Josephson junctions for signal detection

    NASA Astrophysics Data System (ADS)

    Addesso, Paolo; Filatrella, Giovanni; Pierro, Vincenzo

    2012-01-01

    The measurement of the escape time of a Josephson junction might be used to detect the presence of a sinusoidal signal embedded in noise when use of standard signal processing tools can be prohibitive due to the extreme weakness of the source or to the huge amount of data. In this paper we show that the prescriptions for the experimental setup and some physical behaviors depend on the detection strategy. More specifically, by exploitation of the sample mean of escape times to perform detection, two resonant regions are identified. At low frequencies there is a stochastic resonance or activation phenomenon, while near the plasma frequency a geometric resonance appears. Furthermore, detection performance in the geometric resonance region is maximized at the prescribed value of the bias current. The naive sample mean detector is outperformed, in terms of error probability, by the optimal likelihood ratio test. The latter exhibits only geometric resonance, showing monotonically increasing performance as the bias current approaches the junction critical current. In this regime the escape times are vanishingly small and therefore performance is essentially limited by measurement electronics. The behavior of the likelihood ratio and sample mean detector for different values of incoming signal to noise ratio is discussed, and a relationship with the error probability is found. Detectors based on the likelihood ratio test could be employed also to estimate unknown parameters in the applied input signal. As a prototypical example we study the phase estimation problem of a sinusoidal current, which is accomplished by using the filter bank approach. Finally we show that for a physically feasible detector the performances are found to be very close to the Cramer-Rao theoretical bound. Applications might be found, for example, in some astronomical detection problems (where the all-sky gravitational and/or radio wave search for pulsars requires the analysis of nearly sinusoidal

  16. Characterization of escape times of Josephson junctions for signal detection.

    PubMed

    Addesso, Paolo; Filatrella, Giovanni; Pierro, Vincenzo

    2012-01-01

    The measurement of the escape time of a Josephson junction might be used to detect the presence of a sinusoidal signal embedded in noise when use of standard signal processing tools can be prohibitive due to the extreme weakness of the source or to the huge amount of data. In this paper we show that the prescriptions for the experimental setup and some physical behaviors depend on the detection strategy. More specifically, by exploitation of the sample mean of escape times to perform detection, two resonant regions are identified. At low frequencies there is a stochastic resonance or activation phenomenon, while near the plasma frequency a geometric resonance appears. Furthermore, detection performance in the geometric resonance region is maximized at the prescribed value of the bias current. The naive sample mean detector is outperformed, in terms of error probability, by the optimal likelihood ratio test. The latter exhibits only geometric resonance, showing monotonically increasing performance as the bias current approaches the junction critical current. In this regime the escape times are vanishingly small and therefore performance is essentially limited by measurement electronics. The behavior of the likelihood ratio and sample mean detector for different values of incoming signal to noise ratio is discussed, and a relationship with the error probability is found. Detectors based on the likelihood ratio test could be employed also to estimate unknown parameters in the applied input signal. As a prototypical example we study the phase estimation problem of a sinusoidal current, which is accomplished by using the filter bank approach. Finally we show that for a physically feasible detector the performances are found to be very close to the Cramer-Rao theoretical bound. Applications might be found, for example, in some astronomical detection problems (where the all-sky gravitational and/or radio wave search for pulsars requires the analysis of nearly sinusoidal

  17. Estimation and detection of signals in multiplicative noise

    NASA Technical Reports Server (NTRS)

    Willsky, A. S.

    1974-01-01

    We define a class of detection-estimation problems on matrix Lie groups in which the observation noise is multiplicative in nature. By examining the differential versions of the hypotheses, which are bilinear, we are able to derive the relevant likelihood ratio formula and the associated optimal estimation equations for the signal given the observations and the assumption that the signal is present. These estimation equations are of interest in their own right, in that they represent a finite-dimensional optimal solution to a nonlinear estimation problem and consist of a Kalman-Bucy filter along with the on-line computation of the solution of the associated Riccati equation, which is driven by the observations. The usefulness of these results is illustrated via an example concerning the detection of an actuator failure in a rigid-body rotational control system.

  18. Estimation and detection of signals in multiplicative noise

    NASA Technical Reports Server (NTRS)

    Willsky, A. S.

    1973-01-01

    A class of detection-estimation problems on matrix Lie groups is defined in which the observation noise is multiplicative in nature. By examining the differential versions of the hypotheses, which are bilinear in nature, it is possible to derive the relevant likelihood ratio formula and the associated optimal estimation equations for the signal given the observations and the assumption that the signal is present. These estimation equations are of interest in their own right, in that they represent a finite dimensional optimal solution to a nonlinear estimation problem and can be viewed as consisting of a Kalman-Bucy filter along with the on-line computation of the solution of the associated Riccati equation, which is driven by the observations. The usefulness of these results is illustrated via an example concerning the detection of an actuator failure in a rigid body rotational control system.

  19. Optimal BLS: Optimizing transit-signal detection for Keplerian dynamics

    NASA Astrophysics Data System (ADS)

    Ofir, Aviv

    2015-08-01

    Transit surveys, both ground- and space-based, have already accumulated a large number of light curves that span several years. We optimize the search for transit signals for both detection and computational efficiencies by assuming that the searched systems can be described by Keplerian, and propagating the effects of different system parameters to the detection parameters. Importnantly, we mainly consider the information content of the transit signal and not any specific algorithm - and use BLS (Kovács, Zucker, & Mazeh 2002) just as a specific example.We show that the frequency information content of the light curve is primarily determined by the duty cycle of the transit signal, and thus the optimal frequency sampling is found to be cubic and not linear. Further optimization is achieved by considering duty-cycle dependent binning of the phased light curve. By using the (standard) BLS, one is either fairly insensitive to long-period planets or less sensitive to short-period planets and computationally slower by a significant factor of ~330 (for a 3 yr long dataset). We also show how the physical system parameters, such as the host star's size and mass, directly affect transit detection. This understanding can then be used to optimize the search for every star individually.By considering Keplerian dynamics explicitly rather than implicitly one can optimally search the transit signal parameter space. The presented Optimal BLS enhances the detectability of both very short and very long period planets, while allowing such searches to be done with much reduced resources and time. The Matlab/Octave source code for Optimal BLS is made available.

  20. Monaural and interaural intensity discrimination: Level effects and the ``binaural advantage''

    NASA Astrophysics Data System (ADS)

    Stellmack, Mark A.; Viemeister, Neal F.; Byrne, Andrew J.

    2004-08-01

    This study examined whether the level effects seen in monaural intensity discrimination (Weber's law and the ``near miss'') in a two-interval task are also observed in discrimination of interaural intensity differences (IIDs) in a single-interval task. Both tasks were performed for various standard levels of 4-kHz pure tones and broadband noise. The Weber functions (10 log ΔI/I versus I in dB) in the monaural and binaural conditions were parallel. For noise, the Weber functions had slopes close to zero (Weber's law) while the Weber functions for the tones had a mean slope of -0.089 (near miss). The near miss for the monaural and binaural tasks with tones was eliminated when a high-pass masker was gated with the listening intervals. The near-miss was also observed for 250- and 1000-Hz tones in the binaural task despite overall decreased sensitivity to changes in IID at 1000 Hz. The binaural thresholds showed a small (about 2-dB) advantage over monaural thresholds only in the broadband noise conditions. More important, however, is the fact that the level effects seen monaurally are also seen binaurally. This suggests that the basic mechanisms responsible for Weber's law and the near miss are common to monaural and binaural processing.

  1. Binaural jitter improves interaural time-difference sensitivity of cochlear implantees at high pulse rates.

    PubMed

    Laback, Bernhard; Majdak, Piotr

    2008-01-15

    Interaural time difference (ITD) arises whenever a sound outside of the median plane arrives at the two ears. There is evidence that ITD in the rapidly varying fine structure of a sound is most important for sound localization and for understanding speech in noise. Cochlear implants (CIs), neural prosthetic devices that restore hearing in the profoundly deaf, are increasingly implanted to both ears to provide implantees with the advantages of binaural hearing. CI listeners have been shown to be sensitive to fine structure ITD at low pulse rates, but their sensitivity declines at higher pulse rates that are required for speech coding. We hypothesize that this limitation in electric stimulation is at least partially due to binaural adaptation associated with periodic stimulation. Here, we show that introducing binaurally synchronized jitter in the stimulation timing causes large improvements in ITD sensitivity at higher pulse rates. Our experimental results demonstrate that a purely temporal trigger can cause recovery from binaural adaptation. Thus, binaurally jittered stimulation may improve several aspects of binaural hearing in bilateral recipients of neural auditory prostheses. PMID:18182489

  2. Efficient method for events detection in phonocardiographic signals

    NASA Astrophysics Data System (ADS)

    Martinez-Alajarin, Juan; Ruiz-Merino, Ramon

    2005-06-01

    The auscultation of the heart is still the first basic analysis tool used to evaluate the functional state of the heart, as well as the first indicator used to submit the patient to a cardiologist. In order to improve the diagnosis capabilities of auscultation, signal processing algorithms are currently being developed to assist the physician at primary care centers for adult and pediatric population. A basic task for the diagnosis from the phonocardiogram is to detect the events (main and additional sounds, murmurs and clicks) present in the cardiac cycle. This is usually made by applying a threshold and detecting the events that are bigger than the threshold. However, this method usually does not allow the detection of the main sounds when additional sounds and murmurs exist, or it may join several events into a unique one. In this paper we present a reliable method to detect the events present in the phonocardiogram, even in the presence of heart murmurs or additional sounds. The method detects relative maxima peaks in the amplitude envelope of the phonocardiogram, and computes a set of parameters associated with each event. Finally, a set of characteristics is extracted from each event to aid in the identification of the events. Besides, the morphology of the murmurs is also detected, which aids in the differentiation of different diseases that can occur in the same temporal localization. The algorithms have been applied to real normal heart sounds and murmurs, achieving satisfactory results.

  3. Coherent detection and digital signal processing for fiber optic communications

    NASA Astrophysics Data System (ADS)

    Ip, Ezra

    The drive towards higher spectral efficiency in optical fiber systems has generated renewed interest in coherent detection. We review different detection methods, including noncoherent, differentially coherent, and coherent detection, as well as hybrid detection methods. We compare the modulation methods that are enabled and their respective performances in a linear regime. An important system parameter is the number of degrees of freedom (DOF) utilized in transmission. Polarization-multiplexed quadrature-amplitude modulation maximizes spectral efficiency and power efficiency as it uses all four available DOF contained in the two field quadratures in the two polarizations. Dual-polarization homodyne or heterodyne downconversion are linear processes that can fully recover the received signal field in these four DOF. When downconverted signals are sampled at the Nyquist rate, compensation of transmission impairments can be performed using digital signal processing (DSP). Software based receivers benefit from the robustness of DSP, flexibility in design, and ease of adaptation to time-varying channels. Linear impairments, including chromatic dispersion (CD) and polarization-mode dispersion (PMD), can be compensated quasi-exactly using finite impulse response filters. In practical systems, sampling the received signal at 3/2 times the symbol rate is sufficient to enable an arbitrary amount of CD and PMD to be compensated for a sufficiently long equalizer whose tap length scales linearly with transmission distance. Depending on the transmitted constellation and the target bit error rate, the analog-to-digital converter (ADC) should have around 5 to 6 bits of resolution. Digital coherent receivers are naturally suited for the implementation of feedforward carrier recovery, which has superior linewidth tolerance than phase-locked loops, and does not suffer from feedback delay constraints. Differential bit encoding can be used to prevent catastrophic receiver failure due

  4. Signal detection in FDA AERS database using Dirichlet process.

    PubMed

    Hu, Na; Huang, Lan; Tiwari, Ram C

    2015-08-30

    In the recent two decades, data mining methods for signal detection have been developed for drug safety surveillance, using large post-market safety data. Several of these methods assume that the number of reports for each drug-adverse event combination is a Poisson random variable with mean proportional to the unknown reporting rate of the drug-adverse event pair. Here, a Bayesian method based on the Poisson-Dirichlet process (DP) model is proposed for signal detection from large databases, such as the Food and Drug Administration's Adverse Event Reporting System (AERS) database. Instead of using a parametric distribution as a common prior for the reporting rates, as is the case with existing Bayesian or empirical Bayesian methods, a nonparametric prior, namely, the DP, is used. The precision parameter and the baseline distribution of the DP, which characterize the process, are modeled hierarchically. The performance of the Poisson-DP model is compared with some other models, through an intensive simulation study using a Bayesian model selection and frequentist performance characteristics such as type-I error, false discovery rate, sensitivity, and power. For illustration, the proposed model and its extension to address a large amount of zero counts are used to analyze statin drugs for signals using the 2006-2011 AERS data. PMID:25924820

  5. A dual-detector optical receiver for PDM signals detection

    NASA Astrophysics Data System (ADS)

    Chen, Guanyu; Yu, Yu; Zhang, Xinliang

    2016-05-01

    We propose and fabricate a silicon based dual-detector optical receiver, which consists of a two dimensional (2D) grating coupler (GC) and two separate germanium photodetectors (Ge PDs). The 2D GC performs polarization diversity, and thus demultiplexing and detection for polarization division multiplexed (PDM) signals can be achieved. Through a specific design with double-sides illumination, the space charge density can be reduced and the responsivity and saturation power can be improved significantly. The measured dark current, responsivity and bandwidth are 0.86 μA, 1.06 A/W and 36 GHz under 3 V reverse biased voltage, respectively. Both DC currents and eye diagrams are measured for the proposed device and the results validate its performance successfully. The power penalty between the single and dual polarized signals is about 1.9 dB under 10 and 20 Gb/s cases for both the two Ge PDs. The proposed direct detection (DD) for PDM signals with high speed, high responsivity and large saturation power is cost-effective and promising for short reach optical communication.

  6. Asynchronous detection of SSB-SC data signals

    NASA Astrophysics Data System (ADS)

    Sommerville, T. R.; Hanson, J. V.

    Single sideband (SSB) modulation is a special case of combined amplitude and phase modulation that results in suppresion of either the upper or lower sideband of the modulated signal. A study was carried out to combine the bandwidth efficiency of single sideband suppressed carrier transmission with the simplicity of detection offered by envelope detection as proposed by Hanson (1968). In the case of an analog message waveform this has been shown to be impossible, however for a digital data signal it is required only that the envelope have correct value at the sampling instant. Given this weaker constraint a data precoding/predistortion algorithm is proposed that may be applied in order to obtain a solution. The algorithm measures the squared error between the desired and predicted received levels for a given choice of transmitter inputs and determines a correction to the inputs based on the error gradient. The adaptive processor was able to achieve eye openings of up to 60 percent for single sideband suppressed carrier data signals. The best result used a table lookup to generate the initial input estimates, used two input streams, required knowledge of all data values affected by the block under optimization and considered error in the bits preceding and following the block under adaptation.

  7. Median recoil direction as a WIMP directional detection signal

    SciTech Connect

    Green, Anne M.; Morgan, Ben

    2010-03-15

    Direct detection experiments have reached the sensitivity to detect dark matter weakly interacting massive particles (WIMPs). Demonstrating that a putative signal is due to WIMPs, and not backgrounds, is a major challenge, however. The direction dependence of the WIMP scattering rate provides a potential WIMP 'smoking gun'. If the WIMP distribution is predominantly smooth, the Galactic recoil distribution is peaked in the direction opposite to the direction of Solar motion. Previous studies have found that, for an ideal detector, of order 10 WIMP events would be sufficient to reject isotropy, and rule out an isotropic background. We examine how the median recoil direction could be used to confirm the WIMP origin of an anisotropic recoil signal. Specifically, we determine the number of events required to confirm the direction of solar motion as the median inverse recoil direction at 95% confidence. We find that for zero background 31 events are required, a factor of {approx}2 more than are required to simply reject isotropy. We also investigate the effect of a nonzero isotropic background. As the background rate is increased the number of events required increases, initially fairly gradually and then more rapidly, once the signal becomes subdominant. We also discuss the effect of features in the speed distribution at large speeds, as found in recent high resolution simulations, on the median recoil direction.

  8. A dual-detector optical receiver for PDM signals detection.

    PubMed

    Chen, Guanyu; Yu, Yu; Zhang, Xinliang

    2016-05-20

    We propose and fabricate a silicon based dual-detector optical receiver, which consists of a two dimensional (2D) grating coupler (GC) and two separate germanium photodetectors (Ge PDs). The 2D GC performs polarization diversity, and thus demultiplexing and detection for polarization division multiplexed (PDM) signals can be achieved. Through a specific design with double-sides illumination, the space charge density can be reduced and the responsivity and saturation power can be improved significantly. The measured dark current, responsivity and bandwidth are 0.86 μA, 1.06 A/W and 36 GHz under 3 V reverse biased voltage, respectively. Both DC currents and eye diagrams are measured for the proposed device and the results validate its performance successfully. The power penalty between the single and dual polarized signals is about 1.9 dB under 10 and 20 Gb/s cases for both the two Ge PDs. The proposed direct detection (DD) for PDM signals with high speed, high responsivity and large saturation power is cost-effective and promising for short reach optical communication.

  9. Photoacoustic Signal Formation in Heterogeneous Multilayer Systems with Piezoelectric Detection

    NASA Astrophysics Data System (ADS)

    Isaiev, Mykola; Andrusenko, Dmytro; Tytarenko, Alona; Kuzmich, Andrey; Lysenko, Vladimir; Burbelo, Roman

    2014-12-01

    A new efficient model describing photoacoustic (PA) signal formation with piezoelectric detection is reported. Multilayer sandwich-like systems: heterogeneous studied structure—buffer layer—piezoelectric transducers are considered. In these systems, the buffer layer is used for spatial redistribution of thermoelastic force moments generated in the investigated structure. Thus, mechanical properties of this layer play a crucial role to ensure perfect control of the detected voltage formed on a piezoelectric transducer by contribution of different regions of the studied structure. In particular, formation of the voltage signal strongly depends on the point at which the thermoelastic source is applied. Therefore, use of relatively simple linear Green's functions introduced in frames of the Kirchhoff-Love theory is chosen as an efficient approach for the PA signal description. Moreover, excellent agreement between the theoretical model and measured results obtained on a heterogeneous "porous silicon-bulk Si substrate" structure is stated. Furthermore, resolving of the inverse problem with fitting of the experimental curves by the developed model allows reliable evaluation of the thermal conductivity of the nanostructured porous silicon layer.

  10. A dual-detector optical receiver for PDM signals detection

    PubMed Central

    Chen, Guanyu; Yu, Yu; Zhang, Xinliang

    2016-01-01

    We propose and fabricate a silicon based dual-detector optical receiver, which consists of a two dimensional (2D) grating coupler (GC) and two separate germanium photodetectors (Ge PDs). The 2D GC performs polarization diversity, and thus demultiplexing and detection for polarization division multiplexed (PDM) signals can be achieved. Through a specific design with double-sides illumination, the space charge density can be reduced and the responsivity and saturation power can be improved significantly. The measured dark current, responsivity and bandwidth are 0.86 μA, 1.06 A/W and 36 GHz under 3 V reverse biased voltage, respectively. Both DC currents and eye diagrams are measured for the proposed device and the results validate its performance successfully. The power penalty between the single and dual polarized signals is about 1.9 dB under 10 and 20 Gb/s cases for both the two Ge PDs. The proposed direct detection (DD) for PDM signals with high speed, high responsivity and large saturation power is cost-effective and promising for short reach optical communication. PMID:27198501

  11. Auditory induction of discrete tones in signal detection tasks

    NASA Astrophysics Data System (ADS)

    Bennett, K. B.; Parasuraman, R.; Howard, J. H., Jr.; Otoole, A. J.

    1983-10-01

    Auditory induction is the apparent continuation of a fainter sound when alternated rapidly with a more intense interrupting sound. In the present study induction of discrete (non-alternating) tones by contextual tones was examined in three experiments using signal detection methods. Listeners were asked to detect pure tone signals of constant, rising, or falling frequency embedded in noise bursts. The noise bursts were preceded and followed by contextual tones that were designed to produce a constant or changing frequency context. Results indicated that auditory induction is a general factor influencing auditory perception and can be demonstrated either for discrete as well as continuous presentation of sounds. While induction of missing sounds can be beneficial, especially in speech perception, auditory induction can also impair perceptual performance, particularly in monitoring nonspeech sounds for faint signals. Finally, auditory-induction effects can be distinguished from peripheral-masking effects, and although a relation between auditory induction and central masking cannot be ruled out, induction and masking appear to be separate, independent factors, one largely central, and other largely peripheral in nature.

  12. Stochastic model for detection of signals in noise

    PubMed Central

    Klein, Stanley A.; Levi, Dennis M.

    2010-01-01

    Fifty years ago Birdsall, Tanner, and colleagues made rapid progress in developing signal detection theory into a powerful psychophysical tool. One of their major insights was the utility of adding external noise to the signals of interest. These methods have been enhanced in recent years by the addition of multipass and classification-image methods for opening up the black box. There remain a number of as yet unresolved issues. In particular, Birdsall developed a theorem that large amounts of external input noise can linearize nonlinear systems, and Tanner conjectured, with mathematical backup, that what had been previously thought of as a nonlinear system could actually be a linear system with uncertainty. Recent findings, both experimental and theoretical, have validated Birdsall’s theorem and Tanner’s conjecture. However, there have also been experimental and theoretical findings with the opposite outcome. In this paper we present new data and simulations in an attempt to sort out these issues. Our simulations and experiments plus data from others show that Birdsall’s theorem is quite robust. We argue that uncertainty can serve as an explanation for violations of Birdsall’s linearization by noise and also for reports of stochastic resonance. In addition, we modify present models to better handle detection of signals with both noise and pedestal backgrounds. PMID:19884912

  13. Advanced signal processing technique for damage detection in steel tubes

    NASA Astrophysics Data System (ADS)

    Amjad, Umar; Yadav, Susheel Kumar; Dao, Cac Minh; Dao, Kiet; Kundu, Tribikram

    2016-04-01

    In recent years, ultrasonic guided waves gained attention for reliable testing and characterization of metals and composites. Guided wave modes are excited and detected by PZT (Lead Zirconate Titanate) transducers either in transmission or reflection mode. In this study guided waves are excited and detected in the transmission mode and the phase change of the propagating wave modes are recorded. In most of the other studies reported in the literature, the change in the received signal strength (amplitude) is investigated with varying degrees of damage while in this study the change in phase is correlated with the extent of damage. Feature extraction techniques are used for extracting phase and time-frequency information. The main advantage of this approach is that the bonding condition between the transducer and the specimen does not affect the phase while it can affect the strength of recorded signal. Therefore, if the specimen is not damaged but the transducer-specimen bonding is deteriorated then the received signal strength is altered but the phase remains same and thus false positive predictions for damage can be avoided.

  14. A Signal Detection Theory Approach to Evaluating Oculometer Data Quality

    NASA Technical Reports Server (NTRS)

    Latorella, Kara; Lynn, William, III; Barry, John S.; Kelly, Lon; Shih, Ming-Yun

    2013-01-01

    Currently, data quality is described in terms of spatial and temporal accuracy and precision [Holmqvist et al. in press]. While this approach provides precise errors in pixels, or visual angle, often experiments are more concerned with whether subjects'points of gaze can be said to be reliable with respect to experimentally-relevant areas of interest. This paper proposes a method to characterize oculometer data quality using Signal Detection Theory (SDT) [Marcum 1947]. SDT classification results in four cases: Hit (correct report of a signal), Miss (failure to report a ), False Alarm (a signal falsely reported), Correct Reject (absence of a signal correctly reported). A technique is proposed where subjects' are directed to look at points in and outside of an AOI, and the resulting Points of Gaze (POG) are classified as Hits (points known to be internal to an AOI are classified as such), Misses (AOI points are not indicated as such), False Alarms (points external to AOIs are indicated as in the AOI), or Correct Rejects (points external to the AOI are indicated as such). SDT metrics describe performance in terms of discriminability, sensitivity, and specificity. This paper presentation will provide the procedure for conducting this assessment and an example of data collected for AOIs in a simulated flightdeck environment.

  15. An automated approach to detecting signals in electroantennogram data

    USGS Publications Warehouse

    Slone, D.H.; Sullivan, B.T.

    2007-01-01

    Coupled gas chromatography/electroantennographic detection (GC-EAD) is a widely used method for identifying insect olfactory stimulants present in mixtures of volatiles, and it can greatly accelerate the identification of insect semiochemicals. In GC-EAD, voltage changes across an insect's antenna are measured while the antenna is exposed to compounds eluting from a gas chromatograph. The antenna thus serves as a selective GC detector whose output can be compared to that of a "general" GC detector, commonly a flame ionization detector. Appropriate interpretation of GC-EAD results requires that olfaction-related voltage changes in the antenna be distinguishable from background noise that arises inevitably from antennal preparations and the GC-EAD-associated hardware. In this paper, we describe and compare mathematical algorithms for discriminating olfaction-generated signals in an EAD trace from background noise. The algorithms amplify signals by recognizing their characteristic shape and wavelength while suppressing unstructured noise. We have found these algorithms to be both powerful and highly discriminatory even when applied to noisy traces where the signals would be difficult to discriminate by eye. This new methodology removes operator bias as a factor in signal identification, can improve realized sensitivity of the EAD system, and reduces the number of runs required to confirm the identity of an olfactory stimulant. ?? 2007 Springer Science+Business Media, LLC.

  16. Early warning signals detect critical impacts of experimental warming.

    PubMed

    Jarvis, Lauren; McCann, Kevin; Tunney, Tyler; Gellner, Gabriel; Fryxell, John M

    2016-09-01

    Earth's surface temperatures are projected to increase by ~1-4°C over the next century, threatening the future of global biodiversity and ecosystem stability. While this has fueled major progress in the field of physiological trait responses to warming, it is currently unclear whether routine population monitoring data can be used to predict temperature-induced population collapse. Here, we integrate trait performance theory with that of critical tipping points to test whether early warning signals can be reliably used to anticipate thermally induced extinction events. We find that a model parameterized by experimental growth rates exhibits critical slowing down in the vicinity of an experimentally tested critical threshold, suggesting that dynamical early warning signals may be useful in detecting the potentially precipitous onset of population collapse due to global climate change. PMID:27648228

  17. Detection of Gaussian signals in Poisson-modulated interference.

    PubMed

    Streit, R L

    2000-10-01

    Passive broadband detection of target signals by an array of hydrophones in the presence of multiple discrete interferers is analyzed under Gaussian statistics and low signal-to-noise ratio conditions. A nonhomogeneous Poisson-modulated interference process is used to model the ensemble of possible arrival directions of the discrete interferers. Closed-form expressions are derived for the recognition differential of the passive-sonar equation in the presence of Poisson-modulated interference. The interference-compensated recognition differential differs from the classical recognition differential by an additive positive term that depend on the interference-to-noise ratio, the directionality of the Poisson-modulated interference, and the array beam pattern.

  18. Localizing nearby sound sources in a classroom: binaural room impulse responses.

    PubMed

    Shinn-Cunningham, Barbara G; Kopco, Norbert; Martin, Tara J

    2005-05-01

    Binaural room impulse responses (BRIRs) were measured in a classroom for sources at different azimuths and distances (up to 1 m) relative to a manikin located in four positions in a classroom. When the listener is far from all walls, reverberant energy distorts signal magnitude and phase independently at each frequency, altering monaural spectral cues, interaural phase differences, and interaural level differences. For the tested conditions, systematic distortion (comb-filtering) from an early intense reflection is only evident when a listener is very close to a wall, and then only in the ear facing the wall. Especially for a nearby source, interaural cues grow less reliable with increasing source laterality and monaural spectral cues are less reliable in the ear farther from the sound source. Reverberation reduces the magnitude of interaural level differences at all frequencies; however, the direct-sound interaural time difference can still be recovered from the BRIRs measured in these experiments. Results suggest that bias and variability in sound localization behavior may vary systematically with listener location in a room as well as source location relative to the listener, even for nearby sources where there is relatively little reverberant energy.

  19. Progressive anomaly detection in medical data using vital sign signals

    NASA Astrophysics Data System (ADS)

    Gao, Cheng; Lee, Li-Chien; Li, Yao; Chang, Chein-I.; Hu, Peter; Mackenzie, Colin

    2016-05-01

    Vital Sign Signals (VSSs) have been widely used for medical data analysis. One classic approach is to use Logistic Regression Model (LRM) to describe data to be analyzed. There are two challenging issues from this approach. One is how many VSSs needed to be used in the model since there are many VSSs can be used for this purpose. Another is that once the number of VSSs is determined, the follow-up issue what these VSSs are. Up to date these two issues are resolved by empirical selection. This paper addresses these two issues from a hyperspectral imaging perspective. If we view a patient with collected different vital sign signals as a pixel vector in hyperspectral image, then each vital sign signal can be considered as a particular band. In light of this interpretation each VSS can be ranked by band prioritization commonly used by band selection in hyperspectral imaging. In order to resolve the issue of how many VSSs should be used for data analysis we further develop a Progressive Band Processing of Anomaly Detection (PBPAD) which allows users to detect anomalies in medical data using prioritized VSSs one after another so that data changes between bands can be dictated by profiles provided by PBPAD. As a result, there is no need of determining the number of VSSs as well as which VSS should be used because all VSSs are used in their prioritized orders. To demonstrate the utility of PBPAD in medical data analysis anomaly detection is implemented as PBP to find anomalies which correspond to abnormal patients. The data to be used for experiments are data collected in University of Maryland, School of Medicine, Shock Trauma Center (STC). The results will be evaluated by the results obtained by Logistic Regression Model (LRM).

  20. Acoustic Aspects of Photoacoustic Signal Generation and Detection in Gases

    NASA Astrophysics Data System (ADS)

    Miklós, A.

    2015-09-01

    In this paper photoacoustic signal generation and detection in gases is investigated and discussed from the standpoint of acoustics. Four topics are considered: the effect of the absorption-desorption process of modulated and pulsed light on the heat power density released in the gas; the generation of the primary sound by the released heat in an unbounded medium; the excitation of an acoustic resonator by the primary sound; and finally, the generation of the measurable PA signal by a microphone. When light is absorbed by a molecule and the excess energy is relaxed by collisions with the surrounding molecules, the average kinetic energy, thus also the temperature of an ensemble of molecules (called "particle" in acoustics) will increase. In other words heat energy is added to the energy of the particle. The rate of the energy transfer is characterized by the heat power density. A simple two-level model of absorption-desorption is applied for describing the heat power generation process for modulated and pulsed illumination. Sound generation by a laser beam in an unbounded medium is discussed by means of the Green's function technique. It is shown that the duration of the generated sound pulse depends mostly on beam geometry. A photoacoustic signal is mostly detected in a photoacoustic cell composed of acoustic resonators, buffers, filters, etc. It is not easy to interpret the measured PA signal in such a complicated acoustic system. The acoustic response of a PA detector to different kinds of excitations (modulated cw, pulsed, periodic pulse train) is discussed. It is shown that acoustic resonators respond very differently to modulated cw excitation and to excitation by a pulse train. The microphone for detecting the PA signal is also a part of the acoustic system; its properties have to be taken into account by the design of a PA detector. The moving membrane of the microphone absorbs acoustic energy; thus, it may influence the resonance frequency and

  1. Confidence measurement in the light of signal detection theory.

    PubMed

    Massoni, Sébastien; Gajdos, Thibault; Vergnaud, Jean-Christophe

    2014-01-01

    We compare three alternative methods for eliciting retrospective confidence in the context of a simple perceptual task: the Simple Confidence Rating (a direct report on a numerical scale), the Quadratic Scoring Rule (a post-wagering procedure), and the Matching Probability (MP; a generalization of the no-loss gambling method). We systematically compare the results obtained with these three rules to the theoretical confidence levels that can be inferred from performance in the perceptual task using Signal Detection Theory (SDT). We find that the MP provides better results in that respect. We conclude that MP is particularly well suited for studies of confidence that use SDT as a theoretical framework.

  2. Confidence measurement in the light of signal detection theory

    PubMed Central

    Massoni, Sébastien; Gajdos, Thibault; Vergnaud, Jean-Christophe

    2014-01-01

    We compare three alternative methods for eliciting retrospective confidence in the context of a simple perceptual task: the Simple Confidence Rating (a direct report on a numerical scale), the Quadratic Scoring Rule (a post-wagering procedure), and the Matching Probability (MP; a generalization of the no-loss gambling method). We systematically compare the results obtained with these three rules to the theoretical confidence levels that can be inferred from performance in the perceptual task using Signal Detection Theory (SDT). We find that the MP provides better results in that respect. We conclude that MP is particularly well suited for studies of confidence that use SDT as a theoretical framework. PMID:25566135

  3. Time-Varying Distortions of Binaural Information by Bilateral Hearing Aids

    PubMed Central

    Rodriguez, Francisco A.; Portnuff, Cory D. F.; Goupell, Matthew J.; Tollin, Daniel J.

    2016-01-01

    In patients with bilateral hearing loss, the use of two hearing aids (HAs) offers the potential to restore the benefits of binaural hearing, including sound source localization and segregation. However, existing evidence suggests that bilateral HA users’ access to binaural information, namely interaural time and level differences (ITDs and ILDs), can be compromised by device processing. Our objective was to characterize the nature and magnitude of binaural distortions caused by modern digital behind-the-ear HAs using a variety of stimuli and HA program settings. Of particular interest was a common frequency-lowering algorithm known as nonlinear frequency compression, which has not previously been assessed for its effects on binaural information. A binaural beamforming algorithm was also assessed. Wide dynamic range compression was enabled in all programs. HAs were placed on a binaural manikin, and stimuli were presented from an arc of loudspeakers inside an anechoic chamber. Stimuli were broadband noise bursts, 10-Hz sinusoidally amplitude-modulated noise bursts, or consonant–vowel–consonant speech tokens. Binaural information was analyzed in terms of ITDs, ILDs, and interaural coherence, both for whole stimuli and in a time-varying sense (i.e., within a running temporal window) across four different frequency bands (1, 2, 4, and 6 kHz). Key findings were: (a) Nonlinear frequency compression caused distortions of high-frequency envelope ITDs and significantly reduced interaural coherence. (b) For modulated stimuli, all programs caused time-varying distortion of ILDs. (c) HAs altered the relationship between ITDs and ILDs, introducing large ITD–ILD conflicts in some cases. Potential perceptual consequences of measured distortions are discussed. PMID:27698258

  4. An adaptive locally optimal method detecting weak deterministic signals

    NASA Astrophysics Data System (ADS)

    Wang, C. H.

    1983-10-01

    A new method for detecting weak signals in interference and clutter in radar systems is presented. The detector which uses this method is adaptive for an environment varying with time and locally optimal for detecting targets and constant false-alarm ratio (CFAR) for the statistics of interference and clutter varying with time. The loss of CFAR is small, and the detector is also simple in structure. The statistical equivalent transfer characteristic of a rank quantizer which can be used as part of an adaptive locally most powerful detector (ALMP) is obtained. It is shown that the distribution-free Doppler processor of Dillard (1974) is not only a nonparameter detector, but also an ALMP detector under certain conditions.

  5. Signal detection methods for measurement of utility in animals.

    PubMed

    Wright, A A; Nevin, J A

    1974-03-01

    Analytic methods of signal detection theory were employed to assess the utility of reinforcers. Four pigeons were trained to detect the presence or absence of a stimulus by pecking one of two side keys in a trial-by-trial choice paradigm. The relative rate of positive reinforcement for correct choices was varied to offset the biasing effects of electric shock for incorrect right side-key choices. The effects of relative rate of reinforcement on bias were similar at all shock intensities even though the subjects' sensitivity changed during the course of the experiment. The relative rate of reinforcement required to produce equal bias was calculated and plotted against shock intensity to generate utility functions. The relative rate of reinforcement necessary to offset the bias induced by shock was an increasing function of shock intensity.

  6. Scale and translation invariant shape and signal classification and detection

    NASA Astrophysics Data System (ADS)

    Williams, William J.

    2003-12-01

    Highly sophisticated methods for detection and classification of signals and images are available. However, most of these methods are not robust to nonstationary variations such as imposed by Doppler effects or other forms of warping. Fourier methods handle time-shift or frequency shift variations in signals or spatial shifts in images. A number of methods have been developed to overcome these problems. In this paper we discuss some specific approaches that have been motivated by time-frequency analysis. Methodologies developed for images can often be profitably used for time-frequency analysis as well, since these representations are essentially images. The scale transform introduced by Cohen can join Fourier transforms in providing robust representations. Scale changes are common in many signal and image scenarios. We call the representation which results from appropriate transformations of the object of interest the Scale and Translation Invariant Representation or STIR. The STIR method is summarized and results from machine diagnosis, radar, marine mammal sounds, TMJ sounds, speech and word spotting are discussed. Some of the limitations and variations of the method are discussed to provide a rationale for selection of particular elements of the method.

  7. Entropy in DNA Double-Strand Break, Detection and Signaling

    NASA Astrophysics Data System (ADS)

    Zhang, Yang; Schindler, Christina; Heermann, Dieter

    2014-03-01

    In biology, the term entropy is often understood as a measure of disorder - a restrictive interpretation that can even be misleading. Recently it has become clearer and clearer that entropy, contrary to conventional wisdom, can help to order and guide biological processes in living cells. DNA double-strand breaks (DSBs) are among the most dangerous lesions and efficient damage detection and repair is essential for organism viability. However, what remains unknown is the precise mechanism of targeting the site of damage within billions of intact nucleotides and a crowded nuclear environment, a process which is often referred to as recruitment or signaling. Here we show that the change in entropy associated with inflicting a DSB facilitates the recruitment of damage sensor proteins. By means of computational modeling we found that higher mobility and local chromatin structure accelerate protein association at DSB ends. We compared the effect of different chromatin architectures on protein dynamics and concentrations in the vicinity of DSBs, and related these results to experiments on repair in heterochromatin. Our results demonstrate how entropy contributes to a more efficient damage detection. We identify entropy as the physical basis for DNA double-strand break signaling.

  8. Signal detection with criterion noise: Applications to recognition memory

    PubMed Central

    Benjamin, Aaron S.; Diaz, Michael; Wee, Serena

    2010-01-01

    A tacit but fundamental assumption of the Theory of Signal Detection (TSD) is that criterion placement is a noise-free process. This paper challenges that assumption on theoretical and empirical grounds and presents the Noisy Decision Theory of Signal Detection (ND-TSD). Generalized equations for the isosensitivity function and for measures of discrimination that incorporate criterion variability are derived, and the model's relationship with extant models of decision-making in discrimination tasks is examined. An experiment that evaluates recognition memory for ensembles of word stimuli reveals that criterion noise is not trivial in magnitude and contributes substantially to variance in the slope of the isosensitivity function. We discuss how ND-TSD can help explain a number of current and historical puzzles in recognition memory, including the inconsistent relationship between manipulations of learning and the slope of the isosensitivity function, the lack of invariance of the slope with manipulations of bias or payoffs, the effects of aging on the decision-making process in recognition, and the nature of responding in Remember/Know decision tasks. ND-TSD poses novel and theoretically meaningful constraints on theories of recognition and decision-making more generally, and provides a mechanism for rapprochement between theories of decision-making that employ deterministic response rules and those that postulate probabilistic response rules. PMID:19159149

  9. An evaluation of the performance of two binaural beamformers in complex and dynamic multitalker environments

    PubMed Central

    Best, Virginia; Mejia, Jorge; Freeston, Katrina; van Hoesel, Richard J.; Dillon, Harvey

    2016-01-01

    Objective Binaural beamformers are super-directional hearing aids created by combining microphone outputs from each side of the head. While they offer substantial improvements in SNR over conventional directional hearing aids, the benefits (and possible limitations) of these devices in realistic, complex listening situations have not yet been fully explored. In this study we evaluated the performance of two experimental binaural beamformers. Design Testing was carried out using a horizontal loudspeaker array. Background noise was created using recorded conversations. Performance measures included speech intelligibility, localisation in noise, acceptable noise level, subjective ratings, and a novel dynamic speech intelligibility measure. Study sample Participants were 27 listeners with bilateral hearing loss, fitted with BTE prototypes that could be switched between conventional directional or binaural beamformer microphone modes. Results Relative to the conventional directional microphones, both binaural beamformer modes were generally superior for tasks involving fixed frontal targets, but not always for situations involving dynamic target locations. Conclusions Binaural beamformers show promise for enhancing listening in complex situations when the location of the source of interest is predictable. PMID:26140298

  10. The apparent immunity of high-frequency ``transposed'' stimuli to low-frequency binaural interference

    NASA Astrophysics Data System (ADS)

    Bernstein, Leslie R.; Trahiotis, Constantine

    2004-11-01

    Discrimination of interaural temporal disparities (ITDs) was measured with either conventional or transposed ``targets'' centered at 4 kHz. The targets were presented either in the presence or absence of a simultaneously gated diotic noise centered at 500 Hz, the interferer. As expected, the presence of the low-frequency interferer resulted in substantially elevated threshold-ITDs for the conventional high-frequency stimuli. In contrast, these interference effects were absent for ITDs conveyed by the high-frequency transposed targets. The binaural interference effects observed with the conventional high-frequency stimuli were well accounted for, quantitatively, by the model described by Heller and Trahiotis [L. M. Heller and C. Trahiotis, J. Acoust. Soc. Am. 99, 3632-3637 (1996)]. The lack of binaural interference effects observed with the high-frequency transposed stimuli was not predicted by that model. It is suggested that transposed stimuli may be one of a class of stimuli that do not foster an obligatory combination of binaural information between low- and high-frequency regions. Under those conditions that do foster such an obligatory combination, one could still consider models of binaural interference, such as the one described in Heller and Trahiotis, to be valid descriptors of binaural processing. .

  11. Modeling the effects of a single reflection on binaural speech intelligibility.

    PubMed

    Rennies, Jan; Warzybok, Anna; Brand, Thomas; Kollmeier, Birger

    2014-03-01

    Recently the influence of delay and azimuth of a single speech reflection on speech reception thresholds (SRTs) was systematically investigated using frontal, diffuse, and lateral noise [Warzybok et al. (2013). J. Acoust. Soc. Am. 133, 269-282]. The experiments showed that the benefit of an early reflection was independent of its azimuth and mostly independent of noise type, but that the detrimental effect of a late reflection depended on its direction relative to the noise. This study tests if different extensions of a binaural speech intelligibility model can predict these data. The extensions differ in the order in which binaural processing and temporal integration of early reflections take place. Models employing a correction for the detrimental effects of reverberation on speech intelligibility after performing the binaural processing predict SRTs in symmetric masking conditions (frontal, diffuse), but cannot predict the measured interaction of temporal and spatial integration. In contrast, a model extension accounting for the distinction between useful and detrimental reflections before the binaural processing stage predicts the data with an overall R(2) of 0.95. This indicates that any model framework predicting speech intelligibility in rooms should incorporate an interaction between binaural and temporal integration of reflections at a comparatively early stage. PMID:24606290

  12. Directional hearing aid using hybrid adaptive beamformer (HAB) and binaural ITE array

    NASA Astrophysics Data System (ADS)

    Shaw, Scott T.; Larow, Andy J.; Gibian, Gary L.; Sherlock, Laguinn P.; Schulein, Robert

    2002-05-01

    A directional hearing aid algorithm called the Hybrid Adaptive Beamformer (HAB), developed for NIH/NIA, can be applied to many different microphone array configurations. In this project the HAB algorithm was applied to a new array employing in-the-ear microphones at each ear (HAB-ITE), to see if previous HAB performance could be achieved with a more cosmetically acceptable package. With diotic output, the average benefit in threshold SNR was 10.9 dB for three HoH and 11.7 dB for five normal-hearing subjects. These results are slightly better than previous results of equivalent tests with a 3-in. array. With an innovative binaural fitting, a small benefit beyond that provided by diotic adaptive beamforming was observed: 12.5 dB for HoH and 13.3 dB for normal-hearing subjects, a 1.6 dB improvement over the diotic presentation. Subjectively, the binaural fitting preserved binaural hearing abilities, giving the user a sense of space, and providing left-right localization. Thus the goal of creating an adaptive beamformer that simultaneously provides excellent noise reduction and binaural hearing was achieved. Further work remains before the HAB-ITE can be incorporated into a real product, optimizing binaural adaptive beamforming, and integrating the concept with other technologies to produce a viable product prototype. [Work supported by NIH/NIDCD.

  13. Infrasonic detection performance in presence of nuisance signal

    NASA Astrophysics Data System (ADS)

    Charbit, Maurice; Arrowsmith, Stephen; Che, Il-young; Le Pichon, Alexis; Nouvellet, Adrien; Park, Junghyun; Roueff, Francois

    2014-05-01

    The infrasound network of the International Monitoring System (IMS) consists of sixty stations deployed all over the World by the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO). The IMS has been designed to reliably detect, at least by two stations, an explosion greater than 1 kiloton located anywhere on the Earth [1]. Each station is an array of at least four microbarometers with an aperture of 1 to 3 km. The first important issue is to detect the presence of the signal of interest (SOI) embedded in noise. The detector is commonly based on the property that the SOI provides coherent observations on the sensors but not the noise. The statistic of test, called F-stat [2], [5], [6] , calculated in a time cell a few seconds, is commonly used for this purpose. In this paper, we assume that a coherent source is permanently present arriving from an unknown direction of arrivals (DOA). The typical case is the presence of microbaroms or the presence of wind. This source is seen as a nuisance signal (NS). In [4], [3] authors assume that a time cell without the SOI (CH0) is available, whereas a following time cell is considered as the cell under test (CUT). Therefore the DOA and the SNR of the NS can be estimated. If the signal-to-noise ration SNR of the NS is large enough, the distribution of the F-stat under the absence of SOI is known to be a non central Fisher. It follows that the threshold can be performed from a given value of the FAR. The major drawback to keep the NS is that the NS could hide the SOI, this phenomena is similar to the leakage which is a well-known phenomena in the Fourier analysis. An other approach consists to use the DOA estimate of the NS to mitigate the NS by spatial notch filter in the frequency domain. On this approach a new algorithm is provided. To illustrate, numerical results on synthetical and real data are presented, in term of Receiver Operating Characteristic ROC curves. REFERENCES [1] Christie D.R. and Campus P., The IMS

  14. Decision Processes in Discrimination: Fundamental Misrepresentations of Signal Detection Theory

    NASA Technical Reports Server (NTRS)

    Balakrishnan, J. D.

    1998-01-01

    In the first part of this article, I describe a new approach to studying decision making in discrimination tasks that does not depend on the technical assumptions of signal detection theory (e.g., normality of the encoding distributions). Applying these new distribution-free tests to data from three experiments, I show that base rate and payoff manipulations had substantial effects on the participants' encoding distributions but no effect on their decision rules, which were uniformly unbiased in equal and unequal base rate conditions and in symmetric and asymmetric payoff conditions. In the second part of the article, I show that this seemingly paradoxical result is readily explained by the sequential sampling models of discrimination. I then propose a new, "model-free" test for response bias that seems to more properly identify both the nature and direction of the biases induced by the classical bias manipulations.

  15. Types of responding in a signal-detection task

    PubMed Central

    Alsop, Brent; Rowley, Rachael

    1996-01-01

    Four pigeons were trained to discriminate between two line orientations in a two-alternative forced-choice procedure. The distribution of reinforcers for the two types of correct response was varied across conditions. Performance on each trial was recorded separately, including the time taken to make a choice response. Discriminability and response-bias measures were calculated for overall performance, and, following a median split of the data from each condition, for faster and slower choice responses in each condition. Discriminability between the stimuli did not vary systematically as a function of choice latency. Variations of the reinforcer distributions produced larger response biases for the faster responses than for the slower responses. Responses on trials following reinforcers were faster and showed a greater effect of the reinforcer distribution than did other responses. Behavioral models of signal detection should consider the speed of the choice response as a factor modulating the effects of reinforcer distributions. PMID:16812809

  16. Origin of electrical signals for plasma etching endpoint detection

    SciTech Connect

    Sobolewski, Mark A.

    2011-11-14

    Electrical signals are used for endpoint detection in plasma etching, but the origin of the electrical changes observed at endpoint is not known. They may be caused by changes in the gas-phase densities of etch products and reactants or by changes in substrate surface properties such as photoemitted or ion-induced electron yield. To investigate these effects, experiments were performed in an inductively coupled, rf-biased reactor, during CF{sub 4}/Ar etches of SiO{sub 2} films on Si wafers. The rf bias impedance was measured vs. time during etching, simultaneous with Langmuir probe measurements. At endpoint, a decrease in impedance coincided with increases in ion current and electron energy. The data, analyzed by a numerical model of the discharge, indicate that changes in electron emission yield were relatively insignificant or entirely absent. Thus the impedance change is not a surface effect but is, instead, predominantly or entirely a gas-phase phenomenon.

  17. Eliminating the Attentional Blink through Binaural Beats: A Case for Tailored Cognitive Enhancement

    PubMed Central

    Reedijk, Susan A.; Bolders, Anne; Colzato, Lorenza S.; Hommel, Bernhard

    2015-01-01

    Enhancing human cognitive performance is a topic that continues to spark scientific interest. Studies into cognitive-enhancement techniques often fail to take inter-individual differences into account, however, which leads to underestimation of the effectiveness of these techniques. The current study investigated the effect of binaural beats, a cognitive-enhancement technique, on attentional control in an attentional blink (AB) task. As predicted from a neurocognitive approach to cognitive control, high-frequency binaural beats eliminated the AB, but only in individuals with low spontaneous eye-blink rates (indicating low striatal dopamine levels). This suggests that the way in which cognitive-enhancement techniques, such as binaural beats, affect cognitive performance depends on inter-individual differences. PMID:26089802

  18. Signal-detection properties of verbal self-reports.

    PubMed

    Critchfield, T S

    1993-11-01

    The bias (B'H) and discriminability (A') of college students' self-reports about choices made in a delayed identity matching-to-sample task were studied as a function of characteristics of the response about which they reported. Each matching-to-sample trial consisted of two, three, or four simultaneously presented sample stimuli, a 1-s retention interval, and two, three, or four comparison stimuli. One sample stimulus was always reproduced among the comparisons, and choice of the matching comparison in less than 800 ms produced points worth chances in a drawing for money. After each choice, subjects pressed either a "yes" or a "no" button to answer a computer-generated query about whether the choice met the point contingency. The number of sample and comparison stimuli was manipulated across experimental conditions. Rates of successful matching-to-sample choices were negatively correlated with the number of matching-to-sample stimuli, regardless of whether samples or comparisons were manipulated. As in previous studies, subjects exhibited a pronounced bias for reporting successful responses. Self-report bias tended to become less pronounced as matching-to-sample success became less frequent, an outcome consistent with signal-frequency effects in psychophysical research. The bias was also resistant to change, suggesting influences other than signal frequency that remain to be identified. Self-report discriminability tended to decrease with the number of sample stimuli and increase with the number of comparison stimuli, an effect not attributable to differential effects of the two manipulations on matching-to-sample performance. Overall, bias and discriminability indices revealed effects that were not evident in self-report accuracy scores. The results indicate that analyses based on signal-detection theory can improve the description of correspondence between self-reports and their referents and thus contribute to the identification of environmental sources of

  19. Observer detection and discrimination performance as a function of clutter: a signal detection approach

    NASA Astrophysics Data System (ADS)

    Bora, Archana; Aggarwal, Tarun; Lakshminarayanan, Vasudevan

    2011-11-01

    In this paper we investigate the use of signal detection theory (SDT) in predicting target detection and discrimination in disorganized clutter. Two normal observers performed monocular visual search experiments at 25 cm, in the dark. They detected Gabor gratings on an achromatic background cluttered with 2000 or 500 random dots. The targets were displayed at pseudorandom locations from 0-20° and 20-47°, by method of constant stimuli. A contrast-based detection and orientation-based discrimination task was completed in a yes/no or 2-alternative-forced-choice (2AFC) task. The hit rate, false alarm rate, detectability, criterion and bias were analysed. The psychometric function indicated low detection and discrimination thresholds in low clutter that increased in high clutter. Increased clutter showed high hit rates and a false alarm rate that increased with low detectability and liberal criterion. In the detection task, low clutter showed high hit rates and low false alarm rates in the central field. Therefore, SDT proves useful to predict observer performance in visual scenes with disorganized clutter.

  20. PDM-16QAM vector signal generation and detection based on intensity modulation and direct detection

    NASA Astrophysics Data System (ADS)

    Chen, Long; Yu, Jianjun; Li, Xinying

    2016-07-01

    We experimentally demonstrate a novel and simple method to generate and detect high speed polarization-division-multiplexing 16-ary quadrature-amplitude-modulation (PDM-16QAM) vector signal enabled by Mach-Zehnder modulator-based (MZM-based) optical-carrier-suppression (OCS) intensity modulation and direct detection. Due to the adoption of OCS intensity modulation, carrier beating can be avoided at the receiver, and thus polarization de-multiplexing can be implemented by digital-signal-processing-based (DSP-based) cascaded multi-modulus algorithm (CMMA) equalization instead of a polarization tracking system. The change of both amplitude and phase information due to the adoption of OCS modulation can be equalized by DSP-based amplitude and phase precoding at the transmitter. Up to 64-Gb/s PDM-16QAM vector signal is generated and detected after 2-km single-mode fiber-28 (SMF-28) or 20-km large-effective-area fiber (LEAF) transmission with a bit-error-ratio (BER) less than the hard-decision forward-error-correction (HD-FEC) threshold of 3.8×10-3.

  1. Binaural Diplacusis and Its Relationship with Hearing-Threshold Asymmetry.

    PubMed

    Colin, David; Micheyl, Christophe; Girod, Anneline; Truy, Eric; Gallégo, Stéphane

    2016-01-01

    Binaural pitch diplacusis refers to a perceptual anomaly whereby the same sound is perceived as having a different pitch depending on whether it is presented in the left or the right ear. Results in the literature suggest that this phenomenon is more prevalent, and larger, in individuals with asymmetric hearing loss than in individuals with symmetric hearing. However, because studies devoted to this effect have thus far involved small samples, the prevalence of the effect, and its relationship with interaural asymmetries in hearing thresholds, remain unclear. In this study, psychometric functions for interaural pitch comparisons were measured in 55 subjects, including 12 normal-hearing and 43 hearing-impaired participants. Statistically significant pitch differences between the left and right ears were observed in normal-hearing participants, but the effect was usually small (less than 1.5/16 octave, or about 7%). For the hearing-impaired participants, statistically significant interaural pitch differences were found in about three-quarters of the cases. Moreover, for about half of these participants, the difference exceeded 1.5/16 octaves and, in some participants, was as large as or larger than 1/4 octave. This was the case even for the lowest frequency tested, 500 Hz. The pitch differences were weakly, but significantly, correlated with the difference in hearing thresholds between the two ears, such that larger threshold asymmetries were statistically associated with larger pitch differences. For the vast majority of the hearing-impaired participants, the direction of the pitch differences was such that pitch was perceived as higher on the side with the higher (i.e., 'worse') hearing thresholds than on the opposite side. These findings are difficult to reconcile with purely temporal models of pitch perception, but may be accounted for by place-based or spectrotemporal models. PMID:27536884

  2. Binaural Diplacusis and Its Relationship with Hearing-Threshold Asymmetry

    PubMed Central

    Colin, David; Micheyl, Christophe; Girod, Anneline; Truy, Eric; Gallégo, Stéphane

    2016-01-01

    Binaural pitch diplacusis refers to a perceptual anomaly whereby the same sound is perceived as having a different pitch depending on whether it is presented in the left or the right ear. Results in the literature suggest that this phenomenon is more prevalent, and larger, in individuals with asymmetric hearing loss than in individuals with symmetric hearing. However, because studies devoted to this effect have thus far involved small samples, the prevalence of the effect, and its relationship with interaural asymmetries in hearing thresholds, remain unclear. In this study, psychometric functions for interaural pitch comparisons were measured in 55 subjects, including 12 normal-hearing and 43 hearing-impaired participants. Statistically significant pitch differences between the left and right ears were observed in normal-hearing participants, but the effect was usually small (less than 1.5/16 octave, or about 7%). For the hearing-impaired participants, statistically significant interaural pitch differences were found in about three-quarters of the cases. Moreover, for about half of these participants, the difference exceeded 1.5/16 octaves and, in some participants, was as large as or larger than 1/4 octave. This was the case even for the lowest frequency tested, 500 Hz. The pitch differences were weakly, but significantly, correlated with the difference in hearing thresholds between the two ears, such that larger threshold asymmetries were statistically associated with larger pitch differences. For the vast majority of the hearing-impaired participants, the direction of the pitch differences was such that pitch was perceived as higher on the side with the higher (i.e., ‘worse’) hearing thresholds than on the opposite side. These findings are difficult to reconcile with purely temporal models of pitch perception, but may be accounted for by place-based or spectrotemporal models. PMID:27536884

  3. Relating hearing loss and executive functions to hearing aid users' preference for, and speech recognition with, different combinations of binaural noise reduction and microphone directionality

    PubMed Central

    Neher, Tobias

    2014-01-01

    Knowledge of how executive functions relate to preferred hearing aid (HA) processing is sparse and seemingly inconsistent with related knowledge for speech recognition outcomes. This study thus aimed to find out if (1) performance on a measure of reading span (RS) is related to preferred binaural noise reduction (NR) strength, (2) similar relations exist for two different, non-verbal measures of executive function, (3) pure-tone average hearing loss (PTA), signal-to-noise ratio (SNR), and microphone directionality (DIR) also influence preferred NR strength, and (4) preference and speech recognition outcomes are similar. Sixty elderly HA users took part. Six HA conditions consisting of omnidirectional or cardioid microphones followed by inactive, moderate, or strong binaural NR as well as linear amplification were tested. Outcome was assessed at fixed SNRs using headphone simulations of a frontal target talker in a busy cafeteria. Analyses showed positive effects of active NR and DIR on preference, and negative and positive effects of, respectively, strong NR and DIR on speech recognition. Also, while moderate NR was the most preferred NR setting overall, preference for strong NR increased with SNR. No relation between RS and preference was found. However, larger PTA was related to weaker preference for inactive NR and stronger preference for strong NR for both microphone modes. Equivalent (but weaker) relations between worse performance on one non-verbal measure of executive function and the HA conditions without DIR were found. For speech recognition, there were relations between HA condition, PTA, and RS, but their pattern differed from that for preference. Altogether, these results indicate that, while moderate NR works well in general, a notable proportion of HA users prefer stronger NR. Furthermore, PTA and executive functions can account for some of the variability in preference for, and speech recognition with, different binaural NR and DIR settings. PMID

  4. You've found a safety signal--now what?: regulatory implications of industry signal detection activities.

    PubMed

    Kahn, Sidney N

    2007-01-01

    Signals detected by measuring disproportionality of drug-event combinations are only statistical indicators of possible real safety issues, and are not per se necessarily medically important. Nevertheless, once a signal is observed, sponsors are obligated by regulations and ethical considerations to determine whether it represents a new product-associated risk by additional analysis, validation and evaluation of its clinical relevance. Signal strength does not necessarily correlate with medical significance. Strong signals most often represent known, expected and/or medically trivial adverse reactions or confounding by treatment indication, common co-morbidities or other common concomitant treatments. Conversely, any product with reasonably extensive clinical use and reporting of suspected adverse reactions is likely to manifest many weak but clinically unimportant signals, creating significant background 'noise'. Since relatively rare, medically important adverse drug reactions are often likely to manifest as weak signals, sponsors face a potentially onerous burden of evaluating multiple signals in order to distinguish true, clinically important events of concern from spurious signals. This paper discusses the regulatory, clinical and potential legal liability issues that confront industry as a consequence of signal identification activities, including: current and anticipated regulatory requirements for detection, assessment and reporting; the reliability of the data used for signal generation; assessment of clinical relevance; organisational approaches and responses to observed signals; targeted clinical and scientific responses to observed signals; and potential regulatory, legal and commercial impact.

  5. Study of weak vibrating signal detection based on chaotic oscillator in MEMS resonant beam sensor

    NASA Astrophysics Data System (ADS)

    Shi, Huichao; Fan, Shangchun; Xing, Weiwei; Sun, Jinhao

    2015-01-01

    In this paper, the application of weak signal detection based on chaotic oscillator is studied in a MEMS resonant beam sensor. Chaotic oscillator can detect weak signal which is submerged in the background of large noise. According to the frequency and phase characteristic of the output vibrating signal, reference current signal with fixed frequency difference and same phase to the output signal is set. Frequency and phase of the signal are fixed by detection resistor which works as a multiplier. By calculating the maximum Lyapunov exponent, detection threshold is obtained, and motion change of detection system is monitored. The results of numerical simulation and experiment show that this method can effectively detect the weak resonant signal and find the resonant frequency accurately by setting the threshold of the chaotic oscillator, and it is immune to the noise.

  6. A method based on stochastic resonance for the detection of weak analytical signal.

    PubMed

    Wu, Xiaojing; Guo, Weiming; Cai, Wensheng; Shao, Xueguang; Pan, Zhongxiao

    2003-12-23

    An effective method for detection of weak analytical signals with strong noise background is proposed based on the theory of stochastic resonance (SR). Compared with the conventional SR-based algorithms, the proposed algorithm is simplified by changing only one parameter to realize the weak signal detection. Simulation studies revealed that the method performs well in detection of analytical signals in very high level of noise background and is suitable for detecting signals with the different noise level by changing the parameter. Applications of the method to experimental weak signals of X-ray diffraction and Raman spectrum are also investigated. It is found that reliable results can be obtained.

  7. International law implications of the detection of extraterrestrial intelligent signals

    NASA Astrophysics Data System (ADS)

    Kopal, Vladimir

    This paper first considers whether the present law of outer space, as it has been enshrined in five United Nations treaties and other legal documents concerning outer space, provides a satisfactory basis for SETI/CETI activities. In the author's opinion, these activities may serve "the common interest of all mankind in the progress of the exploration and use of outer space for peaceful purposes," as recognized in the 1967 Outer Space Treaty. The use of the radio frequency spectrum for SETI/CETI purposes should be in conformity with the legal principles governing this valuable natural resource, as expressed in the International Telecommunication Convention and related documents, and with allocations of the relevant segments of the spectrum by the competent bodies of the International Telecommunication Union. In the second part the author examines the impact that the detection of extraterrestrial intelligent signals may have on the present body of space law. A possible role for the United Nations in this respect is also explored and a timely interest of the world body in discussing questions relating to this subject is recommended. Consideration of these questions could become a tool helping to concentrate the attention of the world community on problems of common concern and thus to strengthen international cooperation. However, the author believes that a law-making process that would aim at elaborating a special regulation of activities in this field would be premature at this stage. It should be initiated only when the boundary between possibilities and realities is crossed. Finally, the paper outlines some likely transformation in our space law thinking that would be the consequence of the detection of extraterrestrial intelligent signals. Elaboration of the principles and norms to govern relations between the international community of our own planet and other intelligent communities in the universe would add a new dimension to the present body of outer space

  8. Acoustic emission signal classification for gearbox failure detection

    NASA Astrophysics Data System (ADS)

    Shishino, Jun

    The purpose of this research is to develop a methodology and technique to determine the optimal number of clusters in acoustic emission (AE) data obtained from a ground test stand of a rotating H-60 helicopter tail gearbox by using mathematical algorithms and visual inspection. Signs of fatigue crack growth were observed from the AE signals acquired from the result of the optimal number of clusters in a data set. Previous researches have determined the number of clusters by visually inspecting the AE plots from number of iterations. This research is focused on finding the optimal number of clusters in the data set by using mathematical algorithms then using visual verification to confirm it. The AE data were acquired from the ground test stand that simulates the tail end of an H-60 Seahawk at Naval Air Station in Patuxant River, Maryland. The data acquired were filtered to eliminate durations that were greater than 100,000 is and 0 energy hit data to investigate the failure mechanisms occurring on the output bevel gear. From the filtered data, different AE signal parameters were chosen to perform iterations to see which clustering algorithms and number of outputs is the best. The clustering algorithms utilized are the Kohonen Self-organizing Map (SOM), k-mean and Gaussian Mixture Model (GMM). From the clustering iterations, the three cluster criterion algorithms were performed to observe the suggested optimal number of cluster by the criterions. The three criterion algorithms utilized are the Davies-Bouldin, Silhouette and Tou Criterions. After the criterions had suggested the optimal number of cluster for each data set, visual verification by observing the AE plots and statistical analysis of each cluster were performed. By observing the AE plots and the statistical analysis, the optimal number of cluster in the data set and effective clustering algorithms were determined. Along with the optimal number of clusters and effective clustering algorithm, the mechanisms

  9. Dual-microphone and binaural noise reduction techniques for improved speech intelligibility by hearing aid users

    NASA Astrophysics Data System (ADS)

    Yousefian Jazi, Nima

    Spatial filtering and directional discrimination has been shown to be an effective pre-processing approach for noise reduction in microphone array systems. In dual-microphone hearing aids, fixed and adaptive beamforming techniques are the most common solutions for enhancing the desired speech and rejecting unwanted signals captured by the microphones. In fact, beamformers are widely utilized in systems where spatial properties of target source (usually in front of the listener) is assumed to be known. In this dissertation, some dual-microphone coherence-based speech enhancement techniques applicable to hearing aids are proposed. All proposed algorithms operate in the frequency domain and (like traditional beamforming techniques) are purely based on the spatial properties of the desired speech source and does not require any knowledge of noise statistics for calculating the noise reduction filter. This benefit gives our algorithms the ability to address adverse noise conditions, such as situations where interfering talker(s) speaks simultaneously with the target speaker. In such cases, the (adaptive) beamformers lose their effectiveness in suppressing interference, since the noise channel (reference) cannot be built and updated accordingly. This difference is the main advantage of the proposed techniques in the dissertation over traditional adaptive beamformers. Furthermore, since the suggested algorithms are independent of noise estimation, they offer significant improvement in scenarios that the power level of interfering sources are much more than that of target speech. The dissertation also shows the premise behind the proposed algorithms can be extended and employed to binaural hearing aids. The main purpose of the investigated techniques is to enhance the intelligibility level of speech, measured through subjective listening tests with normal hearing and cochlear implant listeners. However, the improvement in quality of the output speech achieved by the

  10. Method for improving the limit of detection in a data signal

    DOEpatents

    Synovec, Robert E.; Yueng, Edward S.

    1989-10-17

    A method for improving the limit of detection for a data set in which experimental noise is uncorrelated along a given abscissa and an analytical signal is correlated to the abscissa, the steps comprising collecting the data set, converting the data set into a data signal including an analytical portion and the experimental noise portion, designating and adjusting a baseline of the data signal to center the experimental noise numerically about a zero reference, and integrating the data signal preserving the corresponding information for each point of the data signal. The steps of the method produce an enhanced integrated data signal which improves the limit of detection of the data signal.

  11. Standardised MedDRA queries: their role in signal detection.

    PubMed

    Mozzicato, Patricia

    2007-01-01

    Standardised MedDRA (Medical Dictionary for Regulatory Activities) queries (SMQs) are a newly developed tool to assist in the retrieval of cases of interest from a MedDRA-coded database. SMQs contain terms related to signs, symptoms, diagnoses, syndromes, physical findings, laboratory and other physiological test data etc, that are associated with the medical condition of interest. They are being developed jointly by CIOMS and the MedDRA Maintenance and Support Services Organization (MSSO) and are provided as an integral part of a MedDRA subscription. During their development, SMQs undergo testing to assure that they are able to retrieve cases of interest within the defined scope of the SMQ. This paper describes the features of SMQs that allow for flexibility in their application, such as 'narrow' and 'broad' sub-searches, hierarchical grouping of sub-searches and search algorithms. In addition, as with MedDRA, users can request changes to SMQs. SMQs are maintained in synchrony with MedDRA versions by internal maintenance processes in the MSSO. The list of safety topics to be developed into SMQs is long and comprehensive. The CIOMS Working Group retains a list of topics to be developed and periodically reviews the list for priority and relevance. As of mid-2007, 37 SMQs are in production use and several more are under development. The potential uses of SMQs in safety analysis will be discussed including their role in signal detection and evaluation. PMID:17604415

  12. Evaluating Classifiers to Detect Arm Movement Intention from EEG Signals

    PubMed Central

    Planelles, Daniel; Hortal, Enrique; Costa, Álvaro; Úbeda, Andrés; Iáñez, Eduardo; Azorín, José M.

    2014-01-01

    This paper presents a methodology to detect the intention to make a reaching movement with the arm in healthy subjects before the movement actually starts. This is done by measuring brain activity through electroencephalographic (EEG) signals that are registered by electrodes placed over the scalp. The preparation and performance of an arm movement generate a phenomenon called event-related desynchronization (ERD) in the mu and beta frequency bands. A novel methodology to characterize this cognitive process based on three sums of power spectral frequencies involved in ERD is presented. The main objective of this paper is to set the benchmark for classifiers and to choose the most convenient. The best results are obtained using an SVM classifier with around 72% accuracy. This classifier will be used in further research to generate the control commands to move a robotic exoskeleton that helps people suffering from motor disabilities to perform the movement. The final aim is that this brain-controlled robotic exoskeleton improves the current rehabilitation processes of disabled people. PMID:25268915

  13. High-Frequency Binaural Beats Increase Cognitive Flexibility: Evidence from Dual-Task Crosstalk

    PubMed Central

    Hommel, Bernhard; Sellaro, Roberta; Fischer, Rico; Borg, Saskia; Colzato, Lorenza S.

    2016-01-01

    Increasing evidence suggests that cognitive-control processes can be configured to optimize either persistence of information processing (by amplifying competition between decision-making alternatives and top-down biasing of this competition) or flexibility (by dampening competition and biasing). We investigated whether high-frequency binaural beats, an auditory illusion suspected to act as a cognitive enhancer, have an impact on cognitive-control configuration. We hypothesized that binaural beats in the gamma range bias the cognitive-control style toward flexibility, which in turn should increase the crosstalk between tasks in a dual-task paradigm. We replicated earlier findings that the reaction time in the first-performed task is sensitive to the compatibility between the responses in the first and the second task—an indication of crosstalk. As predicted, exposing participants to binaural beats in the gamma range increased this effect as compared to a control condition in which participants were exposed to a continuous tone of 340 Hz. These findings provide converging evidence that the cognitive-control style can be systematically biased by inducing particular internal states; that high-frequency binaural beats bias the control style toward more flexibility; and that different styles are implemented by changing the strength of local competition and top-down bias.

  14. Lateralization of high-frequency transposed stimuli under conditions of binaural interference

    NASA Astrophysics Data System (ADS)

    Bernstein, Leslie R.; Trahiotis, Constantine

    2005-04-01

    The purpose of this study was to determine whether binaural interference would occur if ITD-based extents of laterality were measured using high-frequency transposed stimuli as targets. The results of an earlier study [L. R. Bernstein and C. Trahiotis, J. Acoust. Soc. Am. 116, 3062-3069 (2004)], which focused on threshold-ITDs rather than extents of laterality, suggested that high-frequency transposed stimuli might be immune to binaural interference effects resulting from the addition of a spectrally-remote, low-frequency interferer. In contrast to the earlier findings, the data from this study indicate that high-frequency transposed targets can, indeed, be susceptible to binaural interference. High-frequency transposed targets, even when presented along with an interferer, yielded greater extents of ITD-based laterality than did Gaussian noise targets presented in isolation. That is, the enhanced potency of ITDs conveyed by transposed stimuli persisted even in the presence of a low-frequency interferer. Predictions made using an extension of the model of Heller and Trahiotis [L. M. Heller and C. Trahiotis, J. Acoust. Soc. Am. 99, 3632-3637 (1996)] accounted well for binaural interference obtained with conventional Gaussian noise targets but generally over-predicted the amounts of interference found with the transposed targets.

  15. Measures of extents of laterality for high-frequency ``transposed'' stimuli under conditions of binaural interference

    NASA Astrophysics Data System (ADS)

    Bernstein, Leslie R.; Trahiotis, Constantine

    2005-09-01

    Our purpose in this study was to determine whether across-frequency binaural interference would occur if ITD-based extents of laterality were measured using high-frequency transposed stimuli as targets. The results of an earlier study [L. R. Bernstein and C. Trahiotis, J. Acoust. Soc. Am. 116, 3062-3069 (2004)], which focused on threshold-ITDs, rather than extents of laterality, suggested that high-frequency transposed stimuli might be ``immune'' to binaural interference effects resulting from the addition of a spectrally remote, low-frequency interferer. In contrast to the earlier findings, the data from this study indicate that high-frequency transposed targets are susceptible to binaural interference. Nevertheless, high-frequency transposed targets, even when presented along with an interferer, yielded greater extents of ITD-based laterality than did high-frequency Gaussian noise targets presented in isolation. That is, the ``enhanced potency'' of ITDs conveyed by transposed stimuli persisted, even in the presence of a low-frequency interferer. Predictions made using an extension of the model of Heller and Trahiotis [L. M. Heller and C. Trahiotis, J. Acoust. Soc. Am. 99, 3632-3637 (1996)] accounted well for across-frequency binaural interference obtained with conventional Gaussian noise targets but, in all but one case, overpredicted the amounts of interference found with the transposed targets.

  16. Frequency-Shift Detectors Bind Binaural as Well as Monaural Frequency Representations

    ERIC Educational Resources Information Center

    Carcagno, Samuele; Semal, Catherine; Demany, Laurent

    2011-01-01

    Previous psychophysical work provided evidence for the existence of automatic frequency-shift detectors (FSDs) that establish perceptual links between successive sounds. In this study, we investigated the characteristics of the FSDs with respect to the binaural system. Listeners were presented with sound sequences consisting of a chord of pure…

  17. The brain responses to different frequencies of binaural beat sounds on QEEG at cortical level.

    PubMed

    Jirakittayakorn, Nantawachara; Wongsawat, Yodchanan

    2015-01-01

    Beat phenomenon is occurred when two slightly different frequency waves interfere each other. The beat can also occur in the brain by providing two slightly different frequency waves separately each ear. This is called binaural beat. The brain responses to binaural beat are in discussion process whether the brain side and the brain area. Therefore, this study aims to figure out the brain responses to binaural beat by providing different binaural beat frequencies on 250 carrier tone continuously for 30 minutes to participants and using quantitative electroencephalography (QEEG) to interpret the data. The result shows that different responses appear in different beat frequency. Left hemisphere dominance occur in 3 Hz beat within 15 minutes and 15 Hz beat within 5 minutes. Right hemisphere dominance occurs in 10 Hz beat within 25 minute. 6 Hz beat enhances all area of the brain within 10 minutes. 8 Hz and 25 Hz beats have no clearly responses while 40 Hz beat enhances the responses in frontal lobe. These brain responses can be used for brain modulation application to induce the brain activity in further studies.

  18. High-Frequency Binaural Beats Increase Cognitive Flexibility: Evidence from Dual-Task Crosstalk

    PubMed Central

    Hommel, Bernhard; Sellaro, Roberta; Fischer, Rico; Borg, Saskia; Colzato, Lorenza S.

    2016-01-01

    Increasing evidence suggests that cognitive-control processes can be configured to optimize either persistence of information processing (by amplifying competition between decision-making alternatives and top-down biasing of this competition) or flexibility (by dampening competition and biasing). We investigated whether high-frequency binaural beats, an auditory illusion suspected to act as a cognitive enhancer, have an impact on cognitive-control configuration. We hypothesized that binaural beats in the gamma range bias the cognitive-control style toward flexibility, which in turn should increase the crosstalk between tasks in a dual-task paradigm. We replicated earlier findings that the reaction time in the first-performed task is sensitive to the compatibility between the responses in the first and the second task—an indication of crosstalk. As predicted, exposing participants to binaural beats in the gamma range increased this effect as compared to a control condition in which participants were exposed to a continuous tone of 340 Hz. These findings provide converging evidence that the cognitive-control style can be systematically biased by inducing particular internal states; that high-frequency binaural beats bias the control style toward more flexibility; and that different styles are implemented by changing the strength of local competition and top-down bias. PMID:27605922

  19. The Physiological Basis and Clinical Use of the Binaural Interaction Component of the Auditory Brainstem Response.

    PubMed

    Laumen, Geneviève; Ferber, Alexander T; Klump, Georg M; Tollin, Daniel J

    2016-01-01

    The auditory brainstem response (ABR) is a sound-evoked noninvasively measured electrical potential representing the sum of neuronal activity in the auditory brainstem and midbrain. ABR peak amplitudes and latencies are widely used in human and animal auditory research and for clinical screening. The binaural interaction component (BIC) of the ABR stands for the difference between the sum of the monaural ABRs and the ABR obtained with binaural stimulation. The BIC comprises a series of distinct waves, the largest of which (DN1) has been used for evaluating binaural hearing in both normal hearing and hearing-impaired listeners. Based on data from animal and human studies, the authors discuss the possible anatomical and physiological bases of the BIC (DN1 in particular). The effects of electrode placement and stimulus characteristics on the binaurally evoked ABR are evaluated. The authors review how interaural time and intensity differences affect the BIC and, analyzing these dependencies, draw conclusion about the mechanism underlying the generation of the BIC. Finally, the utility of the BIC for clinical diagnoses are summarized. PMID:27232077

  20. High-Frequency Binaural Beats Increase Cognitive Flexibility: Evidence from Dual-Task Crosstalk.

    PubMed

    Hommel, Bernhard; Sellaro, Roberta; Fischer, Rico; Borg, Saskia; Colzato, Lorenza S

    2016-01-01

    Increasing evidence suggests that cognitive-control processes can be configured to optimize either persistence of information processing (by amplifying competition between decision-making alternatives and top-down biasing of this competition) or flexibility (by dampening competition and biasing). We investigated whether high-frequency binaural beats, an auditory illusion suspected to act as a cognitive enhancer, have an impact on cognitive-control configuration. We hypothesized that binaural beats in the gamma range bias the cognitive-control style toward flexibility, which in turn should increase the crosstalk between tasks in a dual-task paradigm. We replicated earlier findings that the reaction time in the first-performed task is sensitive to the compatibility between the responses in the first and the second task-an indication of crosstalk. As predicted, exposing participants to binaural beats in the gamma range increased this effect as compared to a control condition in which participants were exposed to a continuous tone of 340 Hz. These findings provide converging evidence that the cognitive-control style can be systematically biased by inducing particular internal states; that high-frequency binaural beats bias the control style toward more flexibility; and that different styles are implemented by changing the strength of local competition and top-down bias. PMID:27605922

  1. Method and apparatus for automatically detecting patterns in digital point-ordered signals

    SciTech Connect

    Brudnoy, D.M.

    1996-12-31

    The present invention is a method and system for detecting a physical feature of a test piece by detecting a pattern in a signal representing data from inspection of the test piece. The pattern is detected by automated additive decomposition of a digital point-ordered signal which represents the data. The present invention can properly handle a non-periodic signal. A physical parameter of the test piece is measured. A digital point-ordered signal representative of the measured physical parameter is generated. The digital point-ordered signal is decomposed into a baseline signal, a background noise signal, and a peaks/troughs signal. The peaks/troughs from the peaks/troughs signal are located and peaks/troughs information indicating the physical feature of the test piece is output.

  2. Method and apparatus for automatically detecting patterns in digital point-ordered signals

    DOEpatents

    Brudnoy, D.M.

    1998-10-20

    The present invention is a method and system for detecting a physical feature of a test piece by detecting a pattern in a signal representing data from inspection of the test piece. The pattern is detected by automated additive decomposition of a digital point-ordered signal which represents the data. The present invention can properly handle a non-periodic signal. A physical parameter of the test piece is measured. A digital point-ordered signal representative of the measured physical parameter is generated. The digital point-ordered signal is decomposed into a baseline signal, a background noise signal, and a peaks/troughs signal. The peaks/troughs from the peaks/troughs signal are located and peaks/troughs information indicating the physical feature of the test piece is output. 14 figs.

  3. Method and apparatus for automatically detecting patterns in digital point-ordered signals

    DOEpatents

    Brudnoy, David M.

    1998-01-01

    The present invention is a method and system for detecting a physical feature of a test piece by detecting a pattern in a signal representing data from inspection of the test piece. The pattern is detected by automated additive decomposition of a digital point-ordered signal which represents the data. The present invention can properly handle a non-periodic signal. A physical parameter of the test piece is measured. A digital point-ordered signal representative of the measured physical parameter is generated. The digital point-ordered signal is decomposed into a baseline signal, a background noise signal, and a peaks/troughs signal. The peaks/troughs from the peaks/troughs signal are located and peaks/troughs information indicating the physical feature of the test piece is output.

  4. Twin signal signature sensing: Application to shorted winding monitoring, detection and localization

    SciTech Connect

    Streifel, R.J.; Marks, R.J.; El-Sharkawi, A.E.; Kerszenbaum, I.

    1995-12-31

    Using twin signal sensing we propose a method to monitor, detect and localize shorts in power system devices with windings: including rotors, transformers and motors. There has, to date, been no effective way to do so. The most obvious approach, time domain reflectometry, fails due to the reactive coupling of the windings. Twin signal signature sensing of shorts results from identical signals being simultaneously injected in both sides of the windings. The reflected signals are measured and the difference amplified to produce the signature signal. The signature signal characterizes the current state of the windings. When winding shorts are present, the electrical characteristics of the device will be different and thus the signature signal will also change. The changes in the signature signal can be monitored to detect shorted windings. While a device is in operation, the signature signals can be monitored and the development of winding shorts can be diagnosed through the process of novelty detection. After a device is cleaned or otherwise known to be functioning correctly (no winding shorts), signature signals can be collected which represent the healthy device. If a sufficient number of signals can be collected, the signal space representing healthy windings can be characterized. A detection surface can be placed around the healthy signature signals to provide a partition of the signal space into two regions: healthy and faulty. Any signature signal which is not within the healthy signature partition will indicate a faulted device.

  5. Note: On-line weak signal detection via adaptive stochastic resonance.

    PubMed

    Lu, Siliang; He, Qingbo; Kong, Fanrang

    2014-06-01

    We design an instrument with a novel embedded adaptive stochastic resonance (SR) algorithm that consists of a SR module and a digital zero crossing detection module for on-line weak signal detection in digital signal processing applications. The two modules are responsible for noise filtering and adaptive parameter configuration, respectively. The on-line weak signal detection can be stably achieved in seconds. The prototype instrument exhibits an advance of 20 dB averaged signal-to-noise ratio and 5 times averaged adjust R-square as compared to the input noisy signal, in considering different driving frequencies and noise levels.

  6. Electrically detected magnetic resonance signal from iron contaminated Czochralski silicon crystal

    NASA Astrophysics Data System (ADS)

    Mchedlidze, T.; Matsumoto, K.

    1998-04-01

    The electrical detection of magnetic resonance (EDMR) measurement, a detection method for the spin-dependent recombination, was applied to characterize iron contaminated silicon samples grown by the Czochralski method. The observed signal was different than previously reported electron paramagnetic resonance signals from defects in silicon. In addition, as the signal was not detected from similarly contaminated samples prepared from floating zone grown silicon crystal, we propose that the signal originates from defects containing iron and oxygen, namely, from iron decorated oxide precipitates. The dependency of EDMR signal on different experimental conditions (microwave power, illumination intensity, and temperature) were studied.

  7. Note: On-line weak signal detection via adaptive stochastic resonance.

    PubMed

    Lu, Siliang; He, Qingbo; Kong, Fanrang

    2014-06-01

    We design an instrument with a novel embedded adaptive stochastic resonance (SR) algorithm that consists of a SR module and a digital zero crossing detection module for on-line weak signal detection in digital signal processing applications. The two modules are responsible for noise filtering and adaptive parameter configuration, respectively. The on-line weak signal detection can be stably achieved in seconds. The prototype instrument exhibits an advance of 20 dB averaged signal-to-noise ratio and 5 times averaged adjust R-square as compared to the input noisy signal, in considering different driving frequencies and noise levels. PMID:24985875

  8. Suitability of the Binaural Interaction Component for Interaural Electrode Pairing of Bilateral Cochlear Implants.

    PubMed

    Hu, Hongmei; Kollmeier, Birger; Dietz, Mathias

    2016-01-01

    Although bilateral cochlear implants (BiCIs) have succeeded in improving the spatial hearing performance of bilateral CI users, the overall performance is still not comparable with normal hearing listeners. Limited success can be partially caused by an interaural mismatch of the place-of-stimulation in each cochlea. Pairing matched interaural CI electrodes and stimulating them with the same frequency band is expected to facilitate binaural functions such as binaural fusion, localization, or spatial release from masking. It has been shown in animal experiments that the magnitude of the binaural interaction component (BIC) derived from the wave-eV decreases for increasing interaural place of stimulation mismatch. This motivated the investigation of the suitability of an electroencephalography-based objective electrode-frequency fitting procedure based on the BIC for BiCI users. A 61 channel monaural and binaural electrically evoked auditory brainstem response (eABR) recording was performed in 7 MED-EL BiCI subjects so far. These BiCI subjects were directly stimulated at 60% dynamic range with 19.9 pulses per second via a research platform provided by the University of Innsbruck (RIB II). The BIC was derived for several interaural electrode pairs by subtracting the response from binaural stimulation from their summed monaural responses. The BIC based pairing results are compared with two psychoacoustic pairing methods: interaural pulse time difference sensitivity and interaural pitch matching. The results for all three methods analyzed as a function of probe electrode allow for determining a matched pair in more than half of the subjects, with a typical accuracy of ± 1 electrode. This includes evidence for statistically significant tuning of the BIC as a function of probe electrode in human subjects. However, results across the three conditions were sometimes not consistent. These discrepancies will be discussed in the light of pitch plasticity versus less plastic

  9. Suitability of the Binaural Interaction Component for Interaural Electrode Pairing of Bilateral Cochlear Implants.

    PubMed

    Hu, Hongmei; Kollmeier, Birger; Dietz, Mathias

    2016-01-01

    Although bilateral cochlear implants (BiCIs) have succeeded in improving the spatial hearing performance of bilateral CI users, the overall performance is still not comparable with normal hearing listeners. Limited success can be partially caused by an interaural mismatch of the place-of-stimulation in each cochlea. Pairing matched interaural CI electrodes and stimulating them with the same frequency band is expected to facilitate binaural functions such as binaural fusion, localization, or spatial release from masking. It has been shown in animal experiments that the magnitude of the binaural interaction component (BIC) derived from the wave-eV decreases for increasing interaural place of stimulation mismatch. This motivated the investigation of the suitability of an electroencephalography-based objective electrode-frequency fitting procedure based on the BIC for BiCI users. A 61 channel monaural and binaural electrically evoked auditory brainstem response (eABR) recording was performed in 7 MED-EL BiCI subjects so far. These BiCI subjects were directly stimulated at 60% dynamic range with 19.9 pulses per second via a research platform provided by the University of Innsbruck (RIB II). The BIC was derived for several interaural electrode pairs by subtracting the response from binaural stimulation from their summed monaural responses. The BIC based pairing results are compared with two psychoacoustic pairing methods: interaural pulse time difference sensitivity and interaural pitch matching. The results for all three methods analyzed as a function of probe electrode allow for determining a matched pair in more than half of the subjects, with a typical accuracy of ± 1 electrode. This includes evidence for statistically significant tuning of the BIC as a function of probe electrode in human subjects. However, results across the three conditions were sometimes not consistent. These discrepancies will be discussed in the light of pitch plasticity versus less plastic

  10. Baseline Signal Reconstruction for Temperature Compensation in Lamb Wave-Based Damage Detection.

    PubMed

    Liu, Guoqiang; Xiao, Yingchun; Zhang, Hua; Ren, Gexue

    2016-01-01

    Temperature variations have significant effects on propagation of Lamb wave and therefore can severely limit the damage detection for Lamb wave. In order to mitigate the temperature effect, a temperature compensation method based on baseline signal reconstruction is developed for Lamb wave-based damage detection. The method is a reconstruction of a baseline signal at the temperature of current signal. In other words, it compensates the baseline signal to the temperature of current signal. The Hilbert transform is used to compensate the phase of baseline signal. The Orthogonal matching pursuit (OMP) is used to compensate the amplitude of baseline signal. Experiments were conducted on two composite panels to validate the effectiveness of the proposed method. Results show that the proposed method could effectively work for temperature intervals of at least 18 °C with the baseline signal temperature as the center, and can be applied to the actual damage detection. PMID:27529245

  11. Baseline Signal Reconstruction for Temperature Compensation in Lamb Wave-Based Damage Detection

    PubMed Central

    Liu, Guoqiang; Xiao, Yingchun; Zhang, Hua; Ren, Gexue

    2016-01-01

    Temperature variations have significant effects on propagation of Lamb wave and therefore can severely limit the damage detection for Lamb wave. In order to mitigate the temperature effect, a temperature compensation method based on baseline signal reconstruction is developed for Lamb wave-based damage detection. The method is a reconstruction of a baseline signal at the temperature of current signal. In other words, it compensates the baseline signal to the temperature of current signal. The Hilbert transform is used to compensate the phase of baseline signal. The Orthogonal matching pursuit (OMP) is used to compensate the amplitude of baseline signal. Experiments were conducted on two composite panels to validate the effectiveness of the proposed method. Results show that the proposed method could effectively work for temperature intervals of at least 18 °C with the baseline signal temperature as the center, and can be applied to the actual damage detection. PMID:27529245

  12. Linking the sender to the receiver: vocal adjustments by bats to maintain signal detection in noise

    PubMed Central

    Luo, Jinhong; Goerlitz, Holger R.; Brumm, Henrik; Wiegrebe, Lutz

    2015-01-01

    Short-term adjustments of signal characteristics allow animals to maintain reliable communication in noise. Noise-dependent vocal plasticity often involves simultaneous changes in multiple parameters. Here, we quantified for the first time the relative contributions of signal amplitude, duration, and redundancy for improving signal detectability in noise. To this end, we used a combination of behavioural experiments on pale spear-nosed bats (Phyllostomus discolor) and signal detection models. In response to increasing noise levels, all bats raised the amplitude of their echolocation calls by 1.8–7.9 dB (the Lombard effect). Bats also increased signal duration by 13%–85%, corresponding to an increase in detectability of 1.0–5.3 dB. Finally, in some noise conditions, bats increased signal redundancy by producing more call groups. Assuming optimal cognitive integration, this could result in a further detectability improvement by up to 4 dB. Our data show that while the main improvement in signal detectability was due to the Lombard effect, increasing signal duration and redundancy can also contribute markedly to improving signal detectability. Overall, our findings demonstrate that the observed adjustments of signal parameters in noise are matched to how these parameters are processed in the receiver’s sensory system, thereby facilitating signal transmission in fluctuating environments. PMID:26692325

  13. [A New Method for Eliminating Background Signal Drift to Improve the Detection Precision in Continuous Harmonic Detection].

    PubMed

    Zhao, Ying; Zhao, Xue-hong; Wang, Zhe; Zhang, Rui; Wang, Yan

    2015-11-01

    To overcome the second harmonic background signal drift in gas continuous detection based on tunable diode laser absorption spectroscopy(TDLAS), a new method of background elimination was proposed by changing center current of the laser. This method can eliminated the effects of background signal drifting on concentration inversion. Based on the wavelength modulation theory, the theoretical expression of the second harmonic of the background signal is derived. In addition, the second harmonic background signal components and the factors that affect it are described. In different working temperatures, the relationship curve between thelaser current and output light intensity. In the process of continuous detection, we analyzes the feasibility ofchangingthe laser center current extraction of background signal. Combined with the principle of the background signal searching, the LabView flow chart was designed to search background center current. Ammonia (NH₃) was detected by the TDLAS experimental system, which demonstrated the feasibility of the new method. The range of experiment parameters and the range of background center current searches were determined, in the situation that there was only one absorption line in the full laser workspace. The experimental results showed that this method realizes background signal extraction, reduces the error of concentration inversion and the effects of concentration inversion bybackground signal. Thus it improved the detection accuracy of the concentration. In the continuous detection experiment, the standarddeviation of inversion concentration reduced from 2.688 3 to 1.856 1, which demonstrated. that the degree of dispersion of detected concentration is reduced, even eliminate the effects of background signal drifting on concentration inversion and the accuracy of detection is improved. This method provides an effective background drifting elimination approach for improving the detection accuracy of the concentration.

  14. Moving beyond Pure Signal-Detection Models: Comment on Wixted (2007)

    ERIC Educational Resources Information Center

    Parks, Colleen M.; Yonelinas, Andrew P.

    2007-01-01

    The dual-process signal-detection (DPSD) model assumes that recognition memory is based on recollection of qualitative information or on a signal-detection-based familiarity process. The model has proven useful for understanding results from a wide range of memory research, including behavioral, neuropsychological, electrophysiological, and…

  15. Invasive reaction assisted strand-displacement signal amplification for sensitive DNA detection.

    PubMed

    Zou, Bingjie; Song, Qinxin; Wang, Jianping; Liu, Yunlong; Zhou, Guohua

    2014-11-18

    A novel DNA detection assay was proposed by invasive reaction coupled with molecular beacon assisted strand-displacement signal amplification (IRASA). Target DNAs are firstly hybridized to two probes to initiate invasive reaction to produce amplified flaps. Then these flaps are further amplified by strand-displacement signal amplification. The detection limit was around 0.2 pM.

  16. Combined tyramide signal amplification and quantum dots for sensitive and photostable immunofluorescence detection.

    PubMed

    Ness, Jayne M; Akhtar, Rizwan S; Latham, Cecelia B; Roth, Kevin A

    2003-08-01

    Conventional immunofluorescence detection of biologically relevant proteins and antigens in tissue sections is often limited by relatively weak signals that fade rapidly on illumination. We have developed an immunohistochemical protocol that combines the sensitivity of tyramide signal amplification with the photostability of quantum dots to overcome these limitations. This simple method provides a sensitive and stable fluorescence immunohistochemical alternative to standard chromogen detection.

  17. Automated feature detection and identification in digital point-ordered signals

    DOEpatents

    Oppenlander, Jane E.; Loomis, Kent C.; Brudnoy, David M.; Levy, Arthur J.

    1998-01-01

    A computer-based automated method to detect and identify features in digital point-ordered signals. The method is used for processing of non-destructive test signals, such as eddy current signals obtained from calibration standards. The signals are first automatically processed to remove noise and to determine a baseline. Next, features are detected in the signals using mathematical morphology filters. Finally, verification of the features is made using an expert system of pattern recognition methods and geometric criteria. The method has the advantage that standard features can be, located without prior knowledge of the number or sequence of the features. Further advantages are that standard features can be differentiated from irrelevant signal features such as noise, and detected features are automatically verified by parameters extracted from the signals. The method proceeds fully automatically without initial operator set-up and without subjective operator feature judgement.

  18. Vestibular receptor cells and signal detection: bioaccelerometers and the hexagonal sampling of two-dimensional signals

    NASA Technical Reports Server (NTRS)

    Mugler, D. H.; Ross, M. D.

    1990-01-01

    The inner ear contains sensory organs which signal changes in head movement. The vestibular sacs, in particular, are sensitive to linear accelerations. Electron microscopic images have revealed the structure of tiny sensory hair bundles, whose mechanical deformation results in the initiation of neuronal activity and the transmission of electrical signals to the brain. The structure of the hair bundles is shown in this paper to be that of the most efficient two-dimensional phased-array signal processors.

  19. DETECTION OF POTENTIAL TRANSIT SIGNALS IN THE FIRST 12 QUARTERS OF KEPLER MISSION DATA

    SciTech Connect

    Tenenbaum, Peter; Jenkins, Jon M.; Seader, Shawn; Burke, Christopher J.; Christiansen, Jessie L.; Rowe, Jason F.; Caldwell, Douglas A.; Clarke, Bruce D.; Li, Jie; Quintana, Elisa V.; Smith, Jeffrey C.; Thompson, Susan E.; Twicken, Joseph D.; Girouard, Forrest R. [Orbital Sciences Corporation and others

    2013-05-01

    We present the results of a search for potential transit signals in the first three years of photometry data acquired by the Kepler mission. The targets of the search include 112,321 targets that were observed over the full interval and an additional 79,992 targets that were observed for a subset of the full interval. From this set of targets we find a total of 11,087 targets that contain at least one signal that meets the Kepler detection criteria: periodicity of the signal, an acceptable signal-to-noise ratio, and three tests that reject false positives. Each target containing at least one detected signal is then searched repeatedly for additional signals, which represent multi-planet systems of transiting planets. When targets with multiple detections are considered, a total of 18,406 potential transiting planet signals are found in the Kepler mission data set. The detected signals are dominated by events with relatively low signal-to-noise ratios and by events with relatively short periods. The distribution of estimated transit depths appears to peak in the range between 20 and 30 parts per million, with a few detections down to fewer than 10 parts per million. The detections exhibit signal-to-noise ratios from 7.1{sigma}, which is the lower cutoff for detections, to over 10,000{sigma}, and periods ranging from 0.5 days, which is the shortest period searched, to 525 days, which is the upper limit of achievable periods given the length of the data set and the requirement that all detections include at least three transits. The detected signals are compared to a set of known transit events in the Kepler field of view, many of which were identified by alternative methods; the comparison shows that the current search recovery rate for targets with known transit events is 98.3%.

  20. DETECTION OF POTENTIAL TRANSIT SIGNALS IN 16 QUARTERS OF KEPLER MISSION DATA

    SciTech Connect

    Tenenbaum, Peter; Jenkins, Jon M.; Seader, Shawn; Burke, Christopher J.; Christiansen, Jessie L.; Rowe, Jason F.; Caldwell, Douglas A.; Clarke, Bruce D.; Coughlin, Jeffrey L.; Li, Jie; Quintana, Elisa V.; Smith, Jeffrey C.; Thompson, Susan E.; Twicken, Joseph D.; Campbell, Jennifer R.; Girouard, Forrest R. [Orbital Sciences Corporation and others

    2014-03-01

    We present the results of a search for potential transit signals in 4 yr of photometry data acquired by the Kepler mission. The targets of the search include 111,800 stars which were observed for the entire interval and 85,522 stars which were observed for a subset of the interval. We found that 9743 targets contained at least one signal consistent with the signature of a transiting or eclipsing object where the criteria for detection are periodicity of the detected transits, adequate signal-to-noise ratio, and acceptance by a number of tests which reject false positive detections. When targets that had produced a signal were searched repeatedly, an additional 6542 signals were detected on 3223 target stars, for a total of 16,285 potential detections. Comparison of the set of detected signals with a set of known and vetted transit events in the Kepler field of view shows that the recovery rate for these signals is 96.9%. The ensemble properties of the detected signals are reviewed.

  1. Application of Wavelet Analysis Technique in the Signal Denoising of Life Sign Detection

    NASA Astrophysics Data System (ADS)

    Zhen, Zhang; Fang, LIU.

    In life sign detection, radar echo signal is very weak and hard to extract. For solve this problem, weak life signal de-noising based on wavelet transform is studied. Through the studies of wavelet threshold de-noising method, the use of it in weak life signal de-noising in strong noise background, and the verification of simulation by Matlab, the results shows that wavelet threshold de-noising method can remove the noise signal from weak life signal effectively and be an effective de-noising and extraction method for weak life signal.

  2. Digital encoding and detection of voiceband data signals

    NASA Astrophysics Data System (ADS)

    Koneru, R. R.

    1980-12-01

    The codecs considered for investigation are Pulse Code Modulation (PCM), Differential PCM, and Delta Modulation operating at bit rates from 16 to 64 kb/sec. A central result of this study was the identification and evaluation of sampling phase differential effect present in a digital encoding system when sampling clock is not synchronous with an integral multiple of the data modern bit clock. PSK voiceband data signals are allowed to pass through these codecs that are designed for speech or data input signals. Digital encoders considered for investigation are ranked using the above performance metrics. Performance results of these coders are fully discussed and analyzed. Recognition algorithm for voiceband data, speech, and silence signals is developed for complete automation in digital channel efficiency models to achieve the optimum system performance. Pattern recognition approaches are sought to formulate and solve this problem. Maximum likelihood estimation procedure with recursive implementation of algorithm is developed.

  3. Detectability of CO2 Flux Signals by a Space-Based Lidar Mission

    NASA Technical Reports Server (NTRS)

    Hammerling, Dorit M.; Kawa, S. Randolph; Schaefer, Kevin; Doney, Scott; Michalak, Anna M.

    2015-01-01

    Satellite observations of carbon dioxide (CO2) offer novel and distinctive opportunities for improving our quantitative understanding of the carbon cycle. Prospective observations include those from space-based lidar such as the Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) mission. Here we explore the ability of such a mission to detect regional changes in CO2 fluxes. We investigate these using three prototypical case studies, namely the thawing of permafrost in the Northern High Latitudes, the shifting of fossil fuel emissions from Europe to China, and changes in the source-sink characteristics of the Southern Ocean. These three scenarios were used to design signal detection studies to investigate the ability to detect the unfolding of these scenarios compared to a baseline scenario. Results indicate that the ASCENDS mission could detect the types of signals investigated in this study, with the caveat that the study is based on some simplifying assumptions. The permafrost thawing flux perturbation is readily detectable at a high level of significance. The fossil fuel emission detectability is directly related to the strength of the signal and the level of measurement noise. For a nominal (lower) fossil fuel emission signal, only the idealized noise-free instrument test case produces a clearly detectable signal, while experiments with more realistic noise levels capture the signal only in the higher (exaggerated) signal case. For the Southern Ocean scenario, differences due to the natural variability in the ENSO climatic mode are primarily detectable as a zonal increase.

  4. Robust detection of peak signals for lateral flow immunoassays

    NASA Astrophysics Data System (ADS)

    Kim, Jongwon; Kim, Jong Dae; Nahm, Kie Bong; Choi, Eui Yul; Lee, Geumyoung

    2011-02-01

    Template matching method is presented to identify the peaks from the scanned signals of lateral flow immunoassay strips. The template is composed of two pulses separated by the distance of the control and the target ligand line in the assay, and is convolved with the scanned signal to deliver the maximum at the center of the two peaks. The peak regions were identified with the predefined distances from the center. Glycosylated haemoglobin immunoassay strips and fluorescent strip readers from Boditechmed Inc. were tested to estimate the lot and reader variations of the concentration measurands. The results showed the robustness of the propose method.

  5. Techniques and applications for binaural sound manipulation in human-machine interfaces

    NASA Technical Reports Server (NTRS)

    Begault, Durand R.; Wenzel, Elizabeth M.

    1990-01-01

    The implementation of binaural sound to speech and auditory sound cues (auditory icons) is addressed from both an applications and technical standpoint. Techniques overviewed include processing by means of filtering with head-related transfer functions. Application to advanced cockpit human interface systems is discussed, although the techniques are extendable to any human-machine interface. Research issues pertaining to three-dimensional sound displays under investigation at the Aerospace Human Factors Division at NASA Ames Research Center are described.

  6. Techniques and applications for binaural sound manipulation in human-machine interfaces

    NASA Technical Reports Server (NTRS)

    Begault, Durand R.; Wenzel, Elizabeth M.

    1992-01-01

    The implementation of binaural sound to speech and auditory sound cues (auditory icons) is addressed from both an applications and technical standpoint. Techniques overviewed include processing by means of filtering with head-related transfer functions. Application to advanced cockpit human interface systems is discussed, although the techniques are extendable to any human-machine interface. Research issues pertaining to three-dimensional sound displays under investigation at the Aerospace Human Factors Division at NASA Ames Research Center are described.

  7. A novel algorithm for real-time adaptive signal detection and identification

    SciTech Connect

    Sleefe, G.E.; Ladd, M.D.; Gallegos, D.E.; Sicking, C.W.; Erteza, I.A.

    1998-04-01

    This paper describes a novel digital signal processing algorithm for adaptively detecting and identifying signals buried in noise. The algorithm continually computes and updates the long-term statistics and spectral characteristics of the background noise. Using this noise model, a set of adaptive thresholds and matched digital filters are implemented to enhance and detect signals that are buried in the noise. The algorithm furthermore automatically suppresses coherent noise sources and adapts to time-varying signal conditions. Signal detection is performed in both the time-domain and the frequency-domain, thereby permitting the detection of both broad-band transients and narrow-band signals. The detection algorithm also provides for the computation of important signal features such as amplitude, timing, and phase information. Signal identification is achieved through a combination of frequency-domain template matching and spectral peak picking. The algorithm described herein is well suited for real-time implementation on digital signal processing hardware. This paper presents the theory of the adaptive algorithm, provides an algorithmic block diagram, and demonstrate its implementation and performance with real-world data. The computational efficiency of the algorithm is demonstrated through benchmarks on specific DSP hardware. The applications for this algorithm, which range from vibration analysis to real-time image processing, are also discussed.

  8. Robust stochastic resonance: Signal detection and adaptation in impulsive noise

    NASA Astrophysics Data System (ADS)

    Kosko, Bart; Mitaim, Sanya

    2001-11-01

    Stochastic resonance (SR) occurs when noise improves a system performance measure such as a spectral signal-to-noise ratio or a cross-correlation measure. All SR studies have assumed that the forcing noise has finite variance. Most have further assumed that the noise is Gaussian. We show that SR still occurs for the more general case of impulsive or infinite-variance noise. The SR effect fades as the noise grows more impulsive. We study this fading effect on the family of symmetric α-stable bell curves that includes the Gaussian bell curve as a special case. These bell curves have thicker tails as the parameter α falls from 2 (the Gaussian case) to 1 (the Cauchy case) to even lower values. Thicker tails create more frequent and more violent noise impulses. The main feedback and feedforward models in the SR literature show this fading SR effect for periodic forcing signals when we plot either the signal-to-noise ratio or a signal correlation measure against the dispersion of the α-stable noise. Linear regression shows that an exponential law γopt(α)=cAα describes this relation between the impulsive index α and the SR-optimal noise dispersion γopt. The results show that SR is robust against noise ``outliers.'' So SR may be more widespread in nature than previously believed. Such robustness also favors the use of SR in engineering systems. We further show that an adaptive system can learn the optimal noise dispersion for two standard SR models (the quartic bistable model and the FitzHugh-Nagumo neuron model) for the signal-to-noise ratio performance measure. This also favors practical applications of SR and suggests that evolution may have tuned the noise-sensitive parameters of biological systems.

  9. DETECTION OF POTENTIAL TRANSIT SIGNALS IN THE FIRST THREE QUARTERS OF Kepler MISSION DATA

    SciTech Connect

    Tenenbaum, Peter; Christiansen, Jessie L.; Jenkins, Jon M.; Rowe, Jason F.; Seader, Shawn; Caldwell, Douglas A.; Clarke, Bruce D.; Li, Jie; Quintana, Elisa V.; Smith, Jeffrey C.; Stumpe, Martin C.; Thompson, Susan E.; Twicken, Joseph D.; Van Cleve, Jeffrey; Girouard, Forrest R.; Klaus, Todd C. [Orbital Sciences Corporation and others

    2012-03-01

    We present the results of a search for potential transit signals in the first three quarters of photometry data acquired by the Kepler mission. The targets of the search include 151,722 stars which were observed over the full interval and an additional 19,132 stars which were observed for only one or two quarters. From this set of targets we find a total of 5392 detections which meet the Kepler detection criteria: those criteria are periodicity of signal, an acceptable signal-to-noise ratio, and a composition test which rejects spurious detections which contain non-physical combinations of events. The detected signals are dominated by events with relatively low signal-to-noise ratio and by events with relatively short periods. The distribution of estimated transit depths appears to peak in the range between 40 and 100 parts per million, with a few detections down to fewer than 10 parts per million. The detections exhibit signal-to-noise ratios from 7.1{sigma}, which is the lower cutoff for detections, to over 10,000{sigma}, and periods ranging from 0.5 days, which is the lower cutoff used in the procedure, to 109 days, which is the upper limit of achievable periods given the length of the data set and the criteria used for detections. The detected signals are compared to a set of known transit events in the Kepler field of view which were derived by a different method using a longer data interval; the comparison shows that the current search correctly identified 88.1% of the known events. A tabulation of the detected transit signals, examples which illustrate the analysis and detection process, a discussion of future plans and open, potentially fruitful, areas of further research are included.

  10. A novel radar sensor for the non-contact detection of speech signals.

    PubMed

    Jiao, Mingke; Lu, Guohua; Jing, Xijing; Li, Sheng; Li, Yanfeng; Wang, Jianqi

    2010-01-01

    Different speech detection sensors have been developed over the years but they are limited by the loss of high frequency speech energy, and have restricted non-contact detection due to the lack of penetrability. This paper proposes a novel millimeter microwave radar sensor to detect speech signals. The utilization of a high operating frequency and a superheterodyne receiver contributes to the high sensitivity of the radar sensor for small sound vibrations. In addition, the penetrability of microwaves allows the novel sensor to detect speech signals through nonmetal barriers. Results show that the novel sensor can detect high frequency speech energies and that the speech quality is comparable to traditional microphone speech. Moreover, the novel sensor can detect speech signals through a nonmetal material of a certain thickness between the sensor and the subject. Thus, the novel speech sensor expands traditional speech detection techniques and provides an exciting alternative for broader application prospects.

  11. Binaural beats increase interhemispheric alpha-band coherence between auditory cortices.

    PubMed

    Solcà, Marco; Mottaz, Anaïs; Guggisberg, Adrian G

    2016-02-01

    Binaural beats (BBs) are an auditory illusion occurring when two tones of slightly different frequency are presented separately to each ear. BBs have been suggested to alter physiological and cognitive processes through synchronization of the brain hemispheres. To test this, we recorded electroencephalograms (EEG) at rest and while participants listened to BBs or a monaural control condition during which both tones were presented to both ears. We calculated for each condition the interhemispheric coherence, which expressed the synchrony between neural oscillations of both hemispheres. Compared to monaural beats and resting state, BBs enhanced interhemispheric coherence between the auditory cortices. Beat frequencies in the alpha (10 Hz) and theta (4 Hz) frequency range both increased interhemispheric coherence selectively at alpha frequencies. In a second experiment, we evaluated whether this coherence increase has a behavioral aftereffect on binaural listening. No effects were observed in a dichotic digit task performed immediately after BBs presentation. Our results suggest that BBs enhance alpha-band oscillation synchrony between the auditory cortices during auditory stimulation. This effect seems to reflect binaural integration rather than entrainment. PMID:26541421

  12. A Link Loss Model for the On-Body Propagation Channel for Binaural Hearing Aids

    NASA Astrophysics Data System (ADS)

    Chandra, Rohit; Johansson, Anders J.

    2013-12-01

    Binaural hearing aids communicate with each other through a wireless link for synchronization. A propagation model is needed to estimate the ear-to-ear link loss for such binaural hearing aids. The link loss is a critical parameter in a link budget to decide the sensitivity of the transceiver. In this paper, we have presented a model for the deterministic component of the ear-to-ear link loss. The model takes into account the dominant paths having most of the power of the creeping wave from the transceiver in one ear to the transceiver in other ear and the effect of the protruding part of the outer ear called pinna. Simulations are done to validate the model using in-the-ear (ITE) placement of antennas at 2.45 GHz on two heterogeneous phantoms of different age-group and body size. The model agrees with the simulations. The ear-to-ear link loss between the antennas for the binaural hearing aids in the homogeneous SAM phantom is compared with a heterogeneous phantom. It is found that the absence of the pinna and the lossless shell in the SAM phantom underestimate the link loss. This is verified by the measurements on a phantom where we have included the pinnas fabricated by 3D-printing.

  13. Binaural unmasking with multiple adjacent masking electrodes in bilateral cochlear implant users

    PubMed Central

    Lu, Thomas; Litovsky, Ruth; Zeng, Fan-Gang

    2011-01-01

    Bilateral cochlear implant (BiCI) users gain an advantage in noisy situations from a second implant, but their bilateral performance falls short of normal hearing listeners. Channel interactions due to overlapping electrical fields between electrodes can impair speech perception, but its role in limiting binaural hearing performance has not been well characterized. To address the issue, binaural masking level differences (BMLD) for a 125 Hz tone in narrowband noise were measured using a pair of pitch-matched electrodes while simultaneously presenting the same masking noise to adjacent electrodes, representing a more realistic stimulation condition compared to prior studies that used only a single electrode pair. For five subjects, BMLDs averaged 8.9 ± 1.0 dB (mean ± s.e.) in single electrode pairs but dropped to 2.1 ± 0.4 dB when presenting noise on adjacent masking electrodes, demonstrating a negative impact of the additional maskers. Removing the masking noise from only the pitch-matched electrode pair not only lowered thresholds but also resulted in smaller BMLDs. The degree of channel interaction estimated from auditory nerve evoked potentials in three subjects was significantly and negatively correlated with BMLD. The data suggest that if the amount of channel interactions can be reduced, BiCI users may experience some performance improvements related to binaural hearing. PMID:21682415

  14. Temporal weighting of binaural information at low frequencies: Discrimination of dynamic interaural time and level differences.

    PubMed

    Diedesch, Anna C; Stecker, G Christopher

    2015-07-01

    The importance of sound onsets in binaural hearing has been addressed in many studies, particularly at high frequencies, where the onset of the envelope may carry much of the useful binaural information. Some studies suggest that sound onsets might play a similar role in the processing of binaural cues [e.g., fine-structure interaural time differences (ITD)] at low frequencies. This study measured listeners' sensitivity to ITD and interaural level differences (ILD) present in early (i.e., onset) and late parts of 80-ms pure tones of 250-, 500-, and 1000-Hz frequency. Following previous studies, tones carried static interaural cues or dynamic cues that peaked at sound onset and diminished to zero at sound offset or vice versa. Although better thresholds were observed in static than dynamic conditions overall, ITD discrimination was especially impaired, regardless of frequency, when cues were not available at sound onset. Results for ILD followed a similar pattern at 1000 Hz; at lower frequencies, ILD thresholds did not differ significantly between dynamic-cue conditions. The results support the "onset" hypothesis of Houtgast and Plomp [(1968). J. Acoust. Soc. Am. 44, 807-812] for ITD discrimination, but not necessarily ILD discrimination, in low-frequency pure tones.

  15. Development of an Efficient Binaural Simulation for the Analysis of Structural Acoustic Data

    NASA Technical Reports Server (NTRS)

    Lalime, Aimee L.; Johnson, Marty E.; Rizzi, Stephen A. (Technical Monitor)

    2002-01-01

    Binaural or "virtual acoustic" representation has been proposed as a method of analyzing acoustic and vibroacoustic data. Unfortunately, this binaural representation can require extensive computer power to apply the Head Related Transfer Functions (HRTFs) to a large number of sources, as with a vibrating structure. This work focuses on reducing the number of real-time computations required in this binaural analysis through the use of Singular Value Decomposition (SVD) and Equivalent Source Reduction (ESR). The SVD method reduces the complexity of the HRTF computations by breaking the HRTFs into dominant singular values (and vectors). The ESR method reduces the number of sources to be analyzed in real-time computation by replacing sources on the scale of a structural wavelength with sources on the scale of an acoustic wavelength. It is shown that the effectiveness of the SVD and ESR methods improves as the complexity of the source increases. In addition, preliminary auralization tests have shown that the results from both the SVD and ESR methods are indistinguishable from the results found with the exhaustive method.

  16. Method for improving the limit of detection in a data signal

    DOEpatents

    Synovec, R.E.; Yueng, E.S.

    1989-10-17

    Disclosed is a method for improving the limit of detection for a data set in which experimental noise is uncorrelated along a given abscissa and an analytical signal is correlated to the abscissa, the steps comprising collecting the data set, converting the data set into a data signal including an analytical portion and the experimental noise portion, designating and adjusting a baseline of the data signal to center the experimental noise numerically about a zero reference, and integrating the data signal preserving the corresponding information for each point of the data signal. The steps of the method produce an enhanced integrated data signal which improves the limit of detection of the data signal. 8 figs.

  17. Development of failure detection system based on vibration signal for smart artificial heart: in vitro study.

    PubMed

    Tsujimura, Shinichi; Kuwabara, Takashi; Koguchi, Harutoshi; Yamane, Takashi; Tsutsui, Tatsuo; Sankai, Yoshiyuki

    2008-01-01

    To realize safe and effective medical treatment for patients with implantable artificial hearts, we have developed a smart artificial heart (SAH). The SAH can grasp the mechanical condition of the artificial heart and the physiological condition of the patient. The purpose of this study is to develop a failure detection system based on the vibration signal from artificial heart in order to enhance the ability of failure detection for the SAH. We suppose this vibration signal reflects not only the mechanical condition of the artificial heart but also a part of the physiological condition of the patient. The developed failure detection system is composed of a vibration sensor unit and a failure detection algorithm. The algorithm has a standard frequency pattern, which is made from the vibration signal of good condition of both the artificial heart and patient. Observing the difference from the standard frequency pattern, the algorithm detects failure conditions. Therefore, this algorithm does not need prior knowledge of vibration characteristics corresponding to failures. After confirming that the vibration signal are affected by pump speed and pulsation in two kinds of mock circulatory loops, we performed thrombogenesis detection by using the failure detection system in mock circulatory loop with sheep blood. As a result, this system indicated a possibility of detecting the initial sign of thrombogenesis earlier than current signal. In conclusion, we think that this failure detection system can cooperate with other sensor systems of the SAH and enhance the ability of failure detection for the SAH.

  18. The observation of theta wave modulation on brain training by 5 Hz-binaural beat stimulation in seven days.

    PubMed

    Yamsa-Ard, Traisak; Wongsawat, Yodchanan

    2015-01-01

    Traditional buddhist meditation method maybe easy for someone with high experience. However, for the beginner, it is very difficult to keep mental concentration with the tradition way for more than 5 minutes. This research aims to observe effect of the new method for meditation in various analysis methods. A piano music mixed with a 5 Hz (theta band enhancement) binaural beat frequency was used to modulate the brain signals continuously for 7 days. Male of the average age of 33.5±3.84 and female of the average age of 28.6±2.49 were participated. All participants were acquired EEGs twice, before the experiment and seven days after the experiment. We also proposed the observations on the changes of absolute powers, relative powers and brain connectivity (coherence) of the participants. After seven days of training, the absolute power, relative power, and coherence were clearly closer to the normative database. We can initially say that the recommended meditation method can efficiently mimic the effect of having the traditional buddhist meditation on enhancing the delta and theta powers in the brain. PMID:26737822

  19. Nonlinear real-life signal detection with a supervised principal components analysis.

    PubMed

    Zhou, C T; Cai, T X; Cai, T F

    2007-03-01

    A novel strategy named supervised principal components analysis for the detection of a target signal of interest embedded in an unknown noisy environment has been investigated. There are two channels in our detection scheme. Each channel consists of a nonlinear phase-space reconstructor (for embedding a data matrix using the received time series) and a principal components analyzer (for feature extraction), respectively. The output error time series, which results from the difference of both eigenvectors of the correlation data matrices from these two channels, is then analyzed using time-frequency tools, for example, frequency spectrum or Wigner-Ville distribution. Experimental results based on real-life electromagnetic data are presented to demonstrate the detection performance of our algorithm. It is found that weak signals hidden beneath the noise floor can be detected. Furthermore, the robustness of the detection performance clearly illustrated that signal frequencies can be extracted when the signal power is not too low.

  20. Recursive ideal observer detection of known M-ary signals in multiplicative and additive Gaussian noise.

    NASA Technical Reports Server (NTRS)

    Painter, J. H.; Gupta, S. C.

    1973-01-01

    This paper presents the derivation of the recursive algorithms necessary for real-time digital detection of M-ary known signals that are subject to independent multiplicative and additive Gaussian noises. The motivating application is minimum probability of error detection of digital data-link messages aboard civil aircraft in the earth reflection multipath environment. For each known signal, the detector contains one Kalman filter and one probability computer. The filters estimate the multipath disturbance. The estimates and the received signal drive the probability computers. Outputs of all the computers are compared in amplitude to give the signal decision. The practicality and usefulness of the detector are extensively discussed.

  1. Fisher-information condition for enhanced signal detection via stochastic resonance.

    PubMed

    Duan, Fabing; Chapeau-Blondeau, François; Abbott, Derek

    2011-11-01

    Various situations where a signal is enhanced by noise through stochastic resonance are now known. This paper contributes to determining general conditions under which improvement by noise can be a priori decided as feasible or not. We focus on the detection of a known signal in additive white noise. Under the assumptions of a weak signal and a sufficiently large sample size, it is proved, with an inequality based on the Fisher information, that improvement by adding noise is never possible, generically, in these conditions. However, under less restrictive conditions, an example of signal detection is shown with favorable action of adding noise.

  2. High speed microscopy techniques for signaling detection in live cells

    NASA Astrophysics Data System (ADS)

    de Mauro, C.; Cecchetti, C. A.; Alfieri, D.; Borile, Giulia; Urbani, A.; Mongillo, M.; Pavone, F. S.

    2014-05-01

    Alterations in intracellular cardiomyocyte calcium handling have a key role in initiating and sustaining arrhythmias. Arrhythmogenic calcium leak from sarcoplasmic reticulum (SR) can be attributed to all means by which calcium exits the SR store in an abnormal fashion. Abnormal SR calcium exit maymanifest as intracellular Ca2+ sparks and/or Ca2+ waves. Ca2+ signaling in arrhythmogenesis has been mainly studied in isolated cardiomyocytes and given that the extracellular matrix influences both Ca2+ and membrane potential dynamics in the intact heart and underlies environmentally mediated changes, understanding how Ca2+ and voltage are regulated in the intact heart will represent a tremendous advancement in the understanding of arrhythmogenic mechanisms. Using novel high-speed multiphoton microscopy techinques, such as multispot and random access, we investigated animal models with inherited and acquired arrhythmias to assess the role of Ca2+ and voltage signals as arrhythmia triggers in cell and subcellular components of the intact heart and correlate these with electrophysiology.

  3. Composition for detection of cell density signal molecule

    DOEpatents

    Schwarz, Richard I.

    2001-01-01

    Disclosed herein is a novel proteinaceous cell density signal molecule (CDS), which is secreted by fibroblastic cells in culture, preferably tendon cells, and which provides a means by which the cells self-regulate their proliferation and the expression of differentiated function. CDS, and the antibodies which recognize them, are important for the development of diagnostics and treatments for injuries and diseases involving connective tissues, particularly tendon. Also disclosed are methods of production and use.

  4. Coherence specific signal detection via chiral pump-probe spectroscopy.

    PubMed

    Holdaway, David I H; Collini, Elisabetta; Olaya-Castro, Alexandra

    2016-05-21

    We examine transient circular dichroism (TRCD) spectroscopy as a technique to investigate signatures of exciton coherence dynamics under the influence of structured vibrational environments. We consider a pump-probe configuration with a linearly polarized pump and a circularly polarized probe, with a variable angle θ between the two directions of propagation. In our theoretical formalism the signal is decomposed in chiral and achiral doorway and window functions. Using this formalism, we show that the chiral doorway component, which beats during the population time, can be isolated by comparing signals with different values of θ. As in the majority of time-resolved pump-probe spectroscopy, the overall TRCD response shows signatures of both excited and ground state dynamics. However, we demonstrate that the chiral doorway function has only a weak ground state contribution, which can generally be neglected if an impulsive pump pulse is used. These findings suggest that the pump-probe configuration of optical TRCD in the impulsive limit has the potential to unambiguously probe quantum coherence beating in the excited state. We present numerical results for theoretical signals in an example dimer system.

  5. Coherence specific signal detection via chiral pump-probe spectroscopy.

    PubMed

    Holdaway, David I H; Collini, Elisabetta; Olaya-Castro, Alexandra

    2016-05-21

    We examine transient circular dichroism (TRCD) spectroscopy as a technique to investigate signatures of exciton coherence dynamics under the influence of structured vibrational environments. We consider a pump-probe configuration with a linearly polarized pump and a circularly polarized probe, with a variable angle θ between the two directions of propagation. In our theoretical formalism the signal is decomposed in chiral and achiral doorway and window functions. Using this formalism, we show that the chiral doorway component, which beats during the population time, can be isolated by comparing signals with different values of θ. As in the majority of time-resolved pump-probe spectroscopy, the overall TRCD response shows signatures of both excited and ground state dynamics. However, we demonstrate that the chiral doorway function has only a weak ground state contribution, which can generally be neglected if an impulsive pump pulse is used. These findings suggest that the pump-probe configuration of optical TRCD in the impulsive limit has the potential to unambiguously probe quantum coherence beating in the excited state. We present numerical results for theoretical signals in an example dimer system. PMID:27208941

  6. A new ultrasonic signal amplification method for detection of bacteria

    NASA Astrophysics Data System (ADS)

    Kant Shukla, Shiva; Resa López, Pablo; Sierra Sánchez, Carlos; Urréjola, José; Segura, Luis Elvira

    2012-10-01

    A new method is presented that increases the sensitivity of ultrasound-based techniques for detection of bacteria. The technique was developed for the detection of catalase-positive microorganisms. It uses a bubble trapping medium containing hydrogen peroxide that is mixed with the sample for microbiological evaluation. The enzyme catalase is present in catalase-positive bacteria, which induces a rapid hydrolysis of hydrogen peroxide, forming bubbles which remain in the medium. This reaction results in the amplification of the mechanical changes that the microorganisms produce in the medium. The effect can be detected by means of ultrasonic wave amplitude continuous measurement since the bubbles increase the ultrasonic attenuation significantly. It is shown that microorganism concentrations of the order of 105 cells ml-1 can be detected using this method. This allows an improvement of three orders of magnitude in the ultrasonic detection threshold of microorganisms in conventional culture media, and is competitive with modern rapid microbiological methods. It can also be used for the characterization of the enzymatic activity.

  7. Spontaneous Alpha Power Lateralization Predicts Detection Performance in an Un-Cued Signal Detection Task.

    PubMed

    Boncompte, Gonzalo; Villena-González, Mario; Cosmelli, Diego; López, Vladimir

    2016-01-01

    Focusing one's attention by external guiding stimuli towards a specific area of the visual field produces systematical neural signatures. One of the most robust is the change in topological distribution of oscillatory alpha band activity across parieto-occipital cortices. In particular, decreases in alpha activity over contralateral and/or increases over ipsilateral scalp sites, respect to the side of the visual field where attention was focused. This evidence comes mainly from experiments where an explicit cue informs subjects where to focus their attention, thus facilitating detection of an upcoming target stimulus. However, recent theoretical models of attention have highlighted a stochastic or non-deterministic component related to visuospatial attentional allocation. In an attempt to evidence this component, here we analyzed alpha activity in a signal detection paradigm in the lack of informative cues; in the absence of preceding information about the location (and time) of appearance of target stimuli. We believe that the unpredictability of this situation could be beneficial for unveiling this component. Interestingly, although total alpha power did not differ between Seen and Unseen conditions, we found a significant lateralization of alpha activity over parieto-occipital electrodes, which predicted behavioral performance. This effect had a smaller magnitude compared to paradigms in which attention is externally guided (cued). However we believe that further characterization of this spontaneous component of attention is of great importance in the study of visuospatial attentional dynamics. These results support the presence of a spontaneous component of visuospatial attentional allocation and they advance pre-stimulus alpha-band lateralization as one of its neural signatures. PMID:27504824

  8. Spontaneous Alpha Power Lateralization Predicts Detection Performance in an Un-Cued Signal Detection Task

    PubMed Central

    Villena-González, Mario; Cosmelli, Diego; López, Vladimir

    2016-01-01

    Focusing one’s attention by external guiding stimuli towards a specific area of the visual field produces systematical neural signatures. One of the most robust is the change in topological distribution of oscillatory alpha band activity across parieto-occipital cortices. In particular, decreases in alpha activity over contralateral and/or increases over ipsilateral scalp sites, respect to the side of the visual field where attention was focused. This evidence comes mainly from experiments where an explicit cue informs subjects where to focus their attention, thus facilitating detection of an upcoming target stimulus. However, recent theoretical models of attention have highlighted a stochastic or non-deterministic component related to visuospatial attentional allocation. In an attempt to evidence this component, here we analyzed alpha activity in a signal detection paradigm in the lack of informative cues; in the absence of preceding information about the location (and time) of appearance of target stimuli. We believe that the unpredictability of this situation could be beneficial for unveiling this component. Interestingly, although total alpha power did not differ between Seen and Unseen conditions, we found a significant lateralization of alpha activity over parieto-occipital electrodes, which predicted behavioral performance. This effect had a smaller magnitude compared to paradigms in which attention is externally guided (cued). However we believe that further characterization of this spontaneous component of attention is of great importance in the study of visuospatial attentional dynamics. These results support the presence of a spontaneous component of visuospatial attentional allocation and they advance pre-stimulus alpha-band lateralization as one of its neural signatures. PMID:27504824

  9. Response properties of cochlear efferent neurons: monaural vs. binaural stimulation and the effects of noise.

    PubMed

    Liberman, M C

    1988-11-01

    1. Discharge properties of olivocochlear efferent neurons were measured in anesthetized cats. Previous studies of these neurons concentrated on monaural stimulation with tones and found sound-evoked discharge rates rarely exceeded 60 spikes/s (16, 20). In the present study, rates as high as 140 spikes/s were achieved by binaural stimulation and/or the addition of noise. Based on studies on the known effects of electrically stimulating the efferents such high rates of sound-evoked efferent activity probably have significant feedback effects on the auditory periphery. 2. Spontaneous discharge rate (SR) was weakly correlated with threshold among efferent neurons: those with SRs greater than 1 spikes/s were generally more sensitive than spontaneously inactive fibers. The discharge rate measured in the absence of acoustic stimulation was shown to be dependent on stimulation history: some units with zero SR became spontaneously active after several minutes of continuous noise stimulation. 3. For stimulation with monaural tones, efferent excitability varied with characteristic frequency (CF): units with CF less than 10 kHz tended to have lower thresholds, higher discharge rates, and shorter latencies than higher CF units. These differences could be minimized by the addition of broadband noise (see below). 4. When tones were presented to one ear at a time, most efferent units appeared monaural (91%), with roughly two-thirds excited by ipsilateral stimuli and one-third by contralateral stimuli. However, the effects of simultaneous stimulation of the two ears suggested that the great majority of efferent units have binaural inputs: the addition of opposite-ear noise or tones, which presented alone were not excitatory, typically enhanced the response to main-ear stimulation. This type of binaural facilitation was strongest among low-CF efferents when the opposite-ear stimuli were tones, and strongest among high-CF units when the opposite-ear stimulus was broadband noise. 5

  10. Psychophysical Models for Signal Detection with Time Varying Uncertainty. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Gai, E.

    1975-01-01

    Psychophysical models for the behavior of the human operator in detection tasks which include change in detectability, correlation between observations and deferred decisions are developed. Classical Signal Detection Theory (SDT) is discussed and its emphasis on the sensory processes is contrasted to decision strategies. The analysis of decision strategies utilizes detection tasks with time varying signal strength. The classical theory is modified to include such tasks and several optimal decision strategies are explored. Two methods of classifying strategies are suggested. The first method is similar to the analysis of ROC curves, while the second is based on the relation between the criterion level (CL) and the detectability. Experiments to verify the analysis of tasks with changes of signal strength are designed. The results show that subjects are aware of changes in detectability and tend to use strategies that involve changes in the CL's.

  11. Asynchronous Detection of Trials Onset from Raw EEG Signals.

    PubMed

    Lopez-Gordo, M A; Grima Murcia, M D; Padilla, Pablo; Pelayo, F; Fernandez, E

    2016-11-01

    Clinical processing of event-related potentials (ERPs) requires a precise synchrony between the stimulation and the acquisition units that are guaranteed by means of a physical link between them. This precise synchrony is needed since temporal misalignments during trial averaging can lead to high deviations of peak times, thus causing error in diagnosis or inefficiency in classification in brain-computer interfaces (BCIs). Out of the laboratory, mobile EEG systems and BCI headsets are not provided with the physical link, thus being inadequate for acquisition of ERPs. In this study, we propose a method for the asynchronous detection of trials onset from raw EEG without physical links. We validate it with a BCI application based on the dichotic listening task. The user goal was to attend the cued auditory message and to report three keywords contained in it while ignoring the other message. The BCI goal was to detect the attended message from the analysis of auditory ERPs. The rate of successful onset detection in both synchronous (using the real onset) and asynchronous (blind detection of trial onset from raw EEG) was 73% with a synchronization error of less than 1[Formula: see text]ms. The level of synchronization provided by this proposal would allow home-based acquisition of ERPs with low cost BCI headsets and any media player unit without physical links between them. PMID:27377663

  12. FET comparator detects analog signal levels without loading analog device

    NASA Technical Reports Server (NTRS)

    Wallace, H. L.

    1966-01-01

    FET comparator circuit detects discrete analog computer output levels without excessively loading the output amplifier of the computer. An FET common source amplifier is coupled by a differential amplifier to a bistable transistor flip-flop. This circuit provides a digital output for analog voltages above or below a predetermined level.

  13. Improvement of detection limits of PIXE by substrate signal reduction

    NASA Astrophysics Data System (ADS)

    Beaulieu, S.; Nejedly, Z.; Campbell, J. L.; Edwards, G. C.; Dias, G. M.

    2002-04-01

    Limits of detection (LODs) for aerosol samples collected using PIXE International cascade impactors, were improved approximately 50% after reducing the cross-sectional area of the analytical beam based on results obtained from microscope photographs of aerosol deposits. Improvements in LODs were most noticeable for selected elements collected on the smaller stages of the impactor (stages 1-3).

  14. A threshold-based approach for muscle contraction detection from surface EMG signals

    NASA Astrophysics Data System (ADS)

    Morantes, Gaudi; Fernández, Gerardo; Altuve, Miguel

    2013-11-01

    Surface electromyographic (SEMG) signals are commonly used as control signals in prosthetic and orthotic devices. Super cial electrodes are placed on the skin of the subject to acquire its muscular activity through this signal. The muscle contraction episode is then in charge of activating and deactivating these devices. Nevertheless, there is no gold standard" to detect muscle contraction, leading to delayed responses and false and missed detections. This fact motivated us to propose a new approach that compares a smoothed version of the SEMG signal with a xed threshold, in order to detect muscle contraction episodes. After preprocessing the SEMG signal, the smoothed version is obtained using a moving average lter, where three di erent window lengths has been evaluated. The detector was tuned by maximizing sensitivity and speci city and evaluated using SEMG signals obtained from the anterior tibial and gastrocnemius muscles, taken during the walking of ve subjects. Compared with traditional detection methods, we obtain a reduction of 3 ms in the detection delay, an increase of 8% in sensitivity but a decrease of 15% in speci city. Future work is directed to the inclusion of a temporal threshold (a double-threshold approach) to minimize false detections and reduce detection delays.

  15. Research on power-law acoustic transient signal detection based on wavelet transform

    NASA Astrophysics Data System (ADS)

    Han, Jian-hui; Yang, Ri-jie; Wang, Wei

    2007-11-01

    Aiming at the characteristics of acoustic transient signal emitted from antisubmarine weapon which is being dropped into water (torpedo, aerial sonobuoy and rocket assisted depth charge etc.), such as short duration, low SNR, abruptness and instability, based on traditional power-law detector, a new method to detect acoustic transient signal is proposed. Firstly wavelet transform is used to de-noise signal, removes random spectrum components and improves SNR. Then Power- Law detector is adopted to detect transient signal. The simulation results show the method can effectively extract envelop characteristic of transient signal on the condition of low SNR. The performance of WT-Power-Law markedly outgoes that of traditional Power-Law detection method.

  16. Static corrections for enhanced signal detection at IMS seismic arrays

    NASA Astrophysics Data System (ADS)

    Wilkins, Neil; Wookey, James; Selby, Neil

    2016-04-01

    Seismic monitoring forms an important part of the International Monitoring System (IMS) for verifying the Comprehensive nuclear Test Ban Treaty (CTBT). Analysis of seismic data can be used to discriminate between nuclear explosions and the tens of thousands of natural earthquakes of similar magnitude that occur every year. This is known as "forensic seismology", and techniques include measuring the P-to-S wave amplitude ratio, the body-to-surface wave magnitude ratio (mb/Ms), and source depth. Measurement of these seismic discriminants requires very high signal-to-noise ratio (SNR) data, and this has led to the development and deployment of seismic arrays as part of the IMS. Array processing methodologies such as stacking can be used, but optimum SNR improvement needs an accurate estimate of the arrival time of the particular seismic phase. To enhance the imaging capability of IMS arrays, we aim to develop site-specific static corrections to the arrival time as a function of frequency, slowness and backazimuth. Here, we present initial results for the IMS TORD array in Niger. Vespagrams are calculated for various events using the F-statistic to clearly identify seismic phases and measure their arrival times. Observed arrival times are compared with those predicted by 1D and 3D velocity models, and residuals are calculated for a range of backazimuths and slownesses. Finally, we demonstrate the improvement in signal fidelity provided by these corrections.

  17. Vertex evoked potentials in a rating-scale detection task: Relation to signal probability

    NASA Technical Reports Server (NTRS)

    Squires, K. C.; Squires, N. K.; Hillyard, S. A.

    1974-01-01

    Vertex evoked potentials were recorded from human subjects performing in an auditory detection task with rating scale responses. Three values of a priori probability of signal presentation were tested. The amplitudes of the N1 and P3 components of the vertex potential associated with correct detections of the signal were found to be systematically related to the strictness of the response criterion and independent of variations in a priori signal probability. No similar evoked potential components were found associated with signal absent judgements (misses and correct rejections) regardless of the confidence level of the judgement or signal probability. These results strongly support the contention that the form of the vertex evoked response is closely correlated with the subject's psychophysical decision regarding the presence or absence of a threshold level signal.

  18. Signal Detection Techniques for Diagnostic Monitoring of Space Shuttle Main Engine Turbomachinery

    NASA Technical Reports Server (NTRS)

    Coffin, Thomas; Jong, Jen-Yi

    1986-01-01

    An investigation to develop, implement, and evaluate signal analysis techniques for the detection and classification of incipient mechanical failures in turbomachinery is reviewed. A brief description of the Space Shuttle Main Engine (SSME) test/measurement program is presented. Signal analysis techniques available to describe dynamic measurement characteristics are reviewed. Time domain and spectral methods are described, and statistical classification in terms of moments is discussed. Several of these waveform analysis techniques have been implemented on a computer and applied to dynamc signals. A laboratory evaluation of the methods with respect to signal detection capability is described. A unique coherence function (the hyper-coherence) was developed through the course of this investigation, which appears promising as a diagnostic tool. This technique and several other non-linear methods of signal analysis are presented and illustrated by application. Software for application of these techniques has been installed on the signal processing system at the NASA/MSFC Systems Dynamics Laboratory.

  19. Automatic detection of EEG artefacts arising from head movements using EEG and gyroscope signals.

    PubMed

    O'Regan, Simon; Faul, Stephen; Marnane, William

    2013-07-01

    Contamination of EEG signals by artefacts arising from head movements has been a serious obstacle in the deployment of automatic neurological event detection systems in ambulatory EEG. In this paper, we present work on categorizing these head-movement artefacts as one distinct class and on using support vector machines to automatically detect their presence. The use of additional physical signals in detecting head-movement artefacts is also investigated by means of support vector machines classifiers implemented with gyroscope waveforms. Finally, the combination of features extracted from EEG and gyroscope signals is explored in order to design an algorithm which incorporates both physical and physiological signals in accurately detecting artefacts arising from head-movements.

  20. Signal to Noise Ratios of Pulsed and Sinewave Modulated Direct Detection Lidar for IPDA Measurements

    NASA Technical Reports Server (NTRS)

    Sun, Xiaoli; Abshire, James B.

    2011-01-01

    The signal-to-noise ratios have been derived for IPDA lidar using a direct detection receiver for both pulsed and sinewave laser modulation techniques, and the results and laboratory measurements are presented

  1. SIGNAL DETECTION BEHAVIOR IN HUMANS AND RATS: A COMPARISON WITH MATCHED TASKS.

    EPA Science Inventory

    Animal models of human cognitive processes are essential for studying the neurobiological mechanisms of these processes and for developing therapies for intoxication and neurodegenerative diseases. A discrete-trial signal detection task was developed for assessing sustained atten...

  2. Wall lizards display conspicuous signals to conspecifics and reduce detection by avian predators

    PubMed Central

    Stevens, Martin

    2014-01-01

    Visual signals are often under conflicting selection to be hidden from predators while being conspicuous to mates and rivals. Here, we investigated whether 3 different island populations of Aegean wall lizards (Podarcis erhardii) with variable coloration among diverse island habitats exhibit simultaneous camouflage and sexual signals. We examined whether signals appear better tuned to conspecific vision as opposed to that of avian predators, and whether background-matching camouflage and sexual signals are partitioned to specific body regions. This could facilitate both covert sexual signaling and camouflage according to the viewing perspectives of predators and conspecifics. We found that lizards typically appeared twice as conspicuous to conspecifics than to avian predators against the same visual background, largely due to lizards’ enhanced sensitivity to ultraviolet, suggesting that P. erhardii signals are tuned to conspecific vision to reduce detection by predators. Males were more conspicuous than females to both predators and conspecifics. In 2 populations, male backs were relatively more camouflaged to predators compared to signaling flanks, whereas in females, exposed and concealed surfaces were camouflaged to predators and generally did not differ in background matching. These findings indicate that lizard coloration evolves under the competing demands of natural and sexual selection to promote signals that are visible to conspecifics while being less perceptible to avian predators. They also elucidate how interactions between natural and sexual selection influence signal detectability and partitioning to different body regions, highlighting the importance of considering receiver vision, viewing perspectives, and signaling environments in studies of signal evolution. PMID:25419083

  3. Psychophysics, fitting, and signal processing for combined hearing aid and cochlear implant stimulation.

    PubMed

    Francart, Tom; McDermott, Hugh J

    2013-01-01

    The addition of acoustic stimulation to electric stimulation via a cochlear implant has been shown to be advantageous for speech perception in noise, sound quality, music perception, and sound source localization. However, the signal processing and fitting procedures of current cochlear implants and hearing aids were developed independently, precluding several potential advantages of bimodal stimulation, such as improved sound source localization and binaural unmasking of speech in noise. While there is a large and increasing population of implantees who use a hearing aid, there are currently no generally accepted fitting methods for this configuration. It is not practical to fit current commercial devices to achieve optimal binaural loudness balance or optimal binaural cue transmission for arbitrary signals and levels. There are several promising experimental signal processing systems specifically designed for bimodal stimulation. In this article, basic psychophysical studies with electric acoustic stimulation are reviewed, along with the current state of the art in fitting, and experimental signal processing techniques for electric acoustic stimulation.

  4. Wavelet Transform for Real-Time Detection of Action Potentials in Neural Signals

    PubMed Central

    Quotb, Adam; Bornat, Yannick; Renaud, Sylvie

    2011-01-01

    We present a study on wavelet detection methods of neuronal action potentials (APs). Our final goal is to implement the selected algorithms on custom integrated electronics for on-line processing of neural signals; therefore we take real-time computing as a hard specification and silicon area as a price to pay. Using simulated neural signals including APs, we characterize an efficient wavelet method for AP extraction by evaluating its detection rate and its implementation cost. We compare software implementation for three methods: adaptive threshold, discrete wavelet transform (DWT), and stationary wavelet transform (SWT). We evaluate detection rate and implementation cost for detection functions dynamically comparing a signal with an adaptive threshold proportional to its SD, where the signal is the raw neural signal, respectively: (i) non-processed; (ii) processed by a DWT; (iii) processed by a SWT. We also use different mother wavelets and test different data formats to set an optimal compromise between accuracy and silicon cost. Detection accuracy is evaluated together with false negative and false positive detections. Simulation results show that for on-line AP detection implemented on a configurable digital integrated circuit, APs underneath the noise level can be detected using SWT with a well-selected mother wavelet, combined to an adaptive threshold. PMID:21811455

  5. Wavelet transform for real-time detection of action potentials in neural signals.

    PubMed

    Quotb, Adam; Bornat, Yannick; Renaud, Sylvie

    2011-01-01

    We present a study on wavelet detection methods of neuronal action potentials (APs). Our final goal is to implement the selected algorithms on custom integrated electronics for on-line processing of neural signals; therefore we take real-time computing as a hard specification and silicon area as a price to pay. Using simulated neural signals including APs, we characterize an efficient wavelet method for AP extraction by evaluating its detection rate and its implementation cost. We compare software implementation for three methods: adaptive threshold, discrete wavelet transform (DWT), and stationary wavelet transform (SWT). We evaluate detection rate and implementation cost for detection functions dynamically comparing a signal with an adaptive threshold proportional to its SD, where the signal is the raw neural signal, respectively: (i) non-processed; (ii) processed by a DWT; (iii) processed by a SWT. We also use different mother wavelets and test different data formats to set an optimal compromise between accuracy and silicon cost. Detection accuracy is evaluated together with false negative and false positive detections. Simulation results show that for on-line AP detection implemented on a configurable digital integrated circuit, APs underneath the noise level can be detected using SWT with a well-selected mother wavelet, combined to an adaptive threshold.

  6. Signal processing of Shiley heart valve data for fracture detection

    SciTech Connect

    Mullenhoff, C.

    1993-04-01

    Given digital acoustic data emanating from the heart sounds of the beating heart measured from laboratory sheep with implanted Bjoerk-Shiley Convexo-Concave heart valves, it is possible to detect and extract the opening and closing heart beats from the data. Once extracted, spectral or other information can then obtained from the heartbeats and passed on to feature extraction algorithms, neutral networks, or pattern recognizers so that the valve condition, either fractured or intact, may be determined.

  7. Signal processing of Shiley heart valve data for fracture detection

    SciTech Connect

    Mullenhoff, C.

    1993-09-01

    Given digital acoustic data emanating from the heart sounds of the beating heart measured from laboratory sheep with implanted Bjoerk-Shiley Convexo-Concave heart valves, it is possible to detect and extract the opening and closing heart beats from the data. Once extracted, spectral or other information can then obtained from the heartbeats and passed on to feature extraction algorithms, neural networks, or pattern recognizers so that the valve condition, either fractured or intact, may be determined.

  8. Signal detection using the radial basis function coupled map lattice.

    PubMed

    Leung, H; Hennessey, G; Drosopoulos, A

    2000-01-01

    Conventional detection methods used in current marine radar systems do not perform efficiently in detecting small targets embedded in a clutter environment. Based on a recent observation that sea clutter, radar echoes from a sea surface, is chaotic rather than random, we propose using a spatial temporal predictor to reconstruct the chaotic dynamic of sea clutter because electromagnetic wave scattering is a spatial temporal phenomenon which is physically modeled by partial differential equations. The spatial temporal predictor used here is called radial basis function coupled map lattice (RBF-CML) which uses a linear combiner to fuse either measurements in different spatial domains for an RBF prediction or predictions from several RBF nets operated on different spatial regions. Using real-life radar data, it is shown that the RBF-CML is an effective method to reconstruct the sea clutter dynamic. The RBF-CML predictor is then applied to detect small targets in sea clutter using the constant false alarm rate (CFAR) principle. The spatial temporal approach is shown, both theoretically and experimentally, to be superior to a conventional CFAR detector.

  9. Quantum detection of coherent-state signals in the presence of noise

    NASA Technical Reports Server (NTRS)

    Vilnrotter, V. A.; Lau, C. W.

    2003-01-01

    A general method for solving an important class of quantum detection problems will be presented and evaluated. The quantum theory for detecting pure states for communications purposes has been developed over two decades ago, however the mixed state problem representing signal plus noise states has received little attention due to its great complexity. Here we develop a practical model for solving the mixed-state problem using a discrete approximation to the coherent-state representation of signal plus noise density operators.

  10. Objectively measuring signal detectability, contrast, blur and noise in medical images using channelized joint observers

    NASA Astrophysics Data System (ADS)

    Goossens, Bart; Luong, Hiêp; Platiša, Ljiljana; Philips, Wilfried

    2013-03-01

    To improve imaging systems and image processing techniques, objective image quality assessment is essential. Model observers adopting a task-based quality assessment strategy by estimating signal detectability measures, have shown to be quite successful to this end. At the same time, costly and time-consuming human observer experiments can be avoided. However, optimizing images in terms of signal detectability alone, still allows a lot of freedom in terms of the imaging parameters. More specifically, fixing the signal detectability defines a manifold in the imaging parameter space on which different "possible" solutions reside. In this article, we present measures that can be used to distinguish these possible solutions from each other, in terms of image quality factors such as signal blur, noise and signal contrast. Our approach is based on an extended channelized joint observer (CJO) that simultaneously estimates the signal amplitude, scale and detectability. As an application, we use this technique to design k-space trajectories for MRI acquisition. Our technique allows to compare the different spiral trajectories in terms of blur, noise and contrast, even when the signal detectability is estimated to be equal.

  11. Signal detection in l/f noise of SQUID magnetometers

    NASA Technical Reports Server (NTRS)

    Cabrera, B.; Anderson, J. T.

    1978-01-01

    It is shown that the variance on the SQUID power spectrum in the l/f low frequency region is well behaved, i.e., any small frequency band may be treated as white noise in standard power spectrum estimation theory. Specifically a calibration signal is examined at 0.017 Hz with an equivalent energy referred to the SQUID input coil of 1 times 10 to the -30th J and a digitally recorded and analyzed record of 140 hr duration obtained an optimum S/N better than 400. The results are in good agreement with theory. In addition no deviation from the l/f dependence of the noise energy spectrum is seen down to frequencies below 10 to the -5th Hz. A commercially available SQUID and electronics system were used.

  12. Range dependent characteristics in the head-related transfer functions of a bat-head cast: part 2. Binaural characteristics.

    PubMed

    Kim, S; Allen, R; Rowan, D

    2012-12-01

    Further innovations in bio-inspired engineering based on biosonar systems, such as bats, may arise from more detailed understanding of the underlying acoustic processes. This includes the range-dependent properties of bat heads and ears, particularly at the higher frequencies of bat vocalizations. In a companion paper Kim et al (2012 Bioinspir. Biomim.), range-dependent head-related transfer functions of a bat head cast were investigated up to 100 kHz at either ear (i.e. monaural features). The current paper extends this to consider range-dependent spectral and temporal disparities between the two ears (i.e. binaural features), using experimental data and a spherical model of a bat head to provide insights into the physical basis for these features. It was found that binaural temporal and high-frequency binaural spectral features are approximately independent of distance, having the effect of decreasing their angular resolution at close range. In contrast, low-frequency binaural spectral features are strongly distance-dependent, such that angular sensitivity can be maintained by lowering the frequency of the echolocation emission at close range. Together with the companion paper Kim et al, we speculate that distance-dependent low-frequency monaural and binaural features at short range might help explain why some species of bats that drop the frequency of their calls on target approach while approaching a target. This also provides an impetus for the design of effective emissions in sonar engineering applied to similar tasks.

  13. Advanced Geospatial Hydrodynamic Signals Analysis for Tsunami Event Detection and Warning

    NASA Astrophysics Data System (ADS)

    Arbab-Zavar, Banafshe; Sabeur, Zoheir

    2013-04-01

    Current early tsunami warning can be issued upon the detection of a seismic event which may occur at a given location offshore. This also provides an opportunity to predict the tsunami wave propagation and run-ups at potentially affected coastal zones by selecting the best matching seismic event from a database of pre-computed tsunami scenarios. Nevertheless, it remains difficult and challenging to obtain the rupture parameters of the tsunamigenic earthquakes in real time and simulate the tsunami propagation with high accuracy. In this study, we propose a supporting approach, in which the hydrodynamic signal is systematically analysed for traces of a tsunamigenic signal. The combination of relatively low amplitudes of a tsunami signal at deep waters and the frequent occurrence of background signals and noise contributes to a generally low signal to noise ratio for the tsunami signal; which in turn makes the detection of this signal difficult. In order to improve the accuracy and confidence of detection, a re-identification framework in which a tsunamigenic signal is detected via the scan of a network of hydrodynamic stations with water level sensing is performed. The aim is to attempt the re-identification of the same signatures as the tsunami wave spatially propagates through the hydrodynamic stations sensing network. The re-identification of the tsunamigenic signal is technically possible since the tsunami signal at the open ocean itself conserves its birthmarks relating it to the source event. As well as supporting the initial detection and improving the confidence of detection, a re-identified signal is indicative of the spatial range of the signal, and thereby it can be used to facilitate the identification of certain background signals such as wind waves which do not have as large a spatial reach as tsunamis. In this paper, the proposed methodology for the automatic detection of tsunamigenic signals has been achieved using open data from NOAA with a recorded

  14. Automatic detecting method of LED signal lamps on fascia based on color image

    NASA Astrophysics Data System (ADS)

    Peng, Xiaoling; Hou, Wenguang; Ding, Mingyue

    2009-10-01

    Instrument display panel is one of the most important parts of automobiles. Automatic detection of LED signal lamps is critical to ensure the reliability of automobile systems. In this paper, an automatic detection method was developed which is composed of three parts in the automatic detection: the shape of LED lamps, the color of LED lamps, and defect spots inside the lamps. More than hundreds of fascias were detected with the automatic detection algorithm. The speed of the algorithm is quite fast and satisfied with the real-time request of the system. Further, the detection result was demonstrated to be stable and accurate.

  15. Weak signal detection based on the information fusion and chaotic oscillator.

    PubMed

    Xiang, Xiuqiao; Shi, Baochang

    2010-03-01

    Based on the chaotic oscillator, a method for weak signal detection using information fusion technology is proposed in this paper. On the one hand, various methods are employed to the amplitude detection of the same weak periodic signal, then the detection outcomes are fused by the adaptive weighted fusion method. On the other hand, during the detection course, information entropy, statistic distance, and Walsh transform are, respectively, used in the state recognition of chaotic oscillator from the viewpoint of time domain or frequency domain, then the recognition results are fused by the k/l fusion method. Numerical results show that the proposed approach detects signal more precisely, identifies state more accurately, and represents information more completely compared with traditional methods.

  16. Detection of magnetic resonance signals using a magnetoresistive sensor

    SciTech Connect

    Budker, Dmitry; Pines, Alexander; Xu, Shoujun; Hilty, Christian; Ledbetter, Micah P; Bouchard, Louis S

    2013-10-01

    A method and apparatus are described wherein a micro sample of a fluidic material may be assayed without sample contamination using NMR techniques, in combination with magnetoresistive sensors. The fluidic material to be assayed is first subject to pre-polarization, in one embodiment, by passage through a magnetic field. The magnetization of the fluidic material is then subject to an encoding process, in one embodiment an rf-induced inversion by passage through an adiabatic fast-passage module. Thereafter, the changes in magnetization are detected by a pair of solid-state magnetoresistive sensors arranged in gradiometer mode. Miniaturization is afforded by the close spacing of the various modules.

  17. Detection of low-amplitude in vivo intrinsic signals from an optical imager of retinal function

    NASA Astrophysics Data System (ADS)

    Barriga, Eduardo S.; T'so, Dan; Pattichis, Marios; Kwon, Young; Kardon, Randy; Abramoff, Michael; Soliz, Peter

    2006-02-01

    In the early stages of some retinal diseases, such as glaucoma, loss of retinal activity may be difficult to detect with today's clinical instruments. Many of today's instruments focus on detecting changes in anatomical structures, such as the nerve fiber layer. Our device, which is based on a modified fundus camera, seeks to detect changes in optical signals that reflect functional changes in the retina. The functional imager uses a patterned stimulus at wavelength of 535nm. An intrinsic functional signal is collected at a near infrared wavelength. Measured changes in reflectance in response to the visual stimulus are on the order of 0.1% to 1% of the total reflected intensity level, which makes the functional signal difficult to detect by standard methods because it is masked by other physiological signals and by imaging system noise. In this paper, we analyze the video sequences from a set of 60 experiments with different patterned stimuli from cats. Using a set of statistical techniques known as Independent Component Analysis (ICA), we estimate the signals present in the videos. Through controlled simulation experiments, we quantify the limits of signal strength in order to detect the physiological signal of interest. The results of the analysis show that, in principle, signal levels of 0.1% (-30dB) can be detected. The study found that in 86% of the animal experiments the patterned stimuli effects on the retina can be detected and extracted. The analysis of the different responses extracted from the videos can give an insight of the functional processes present during the stimulation of the retina.

  18. Coherent (photon) vs incoherent (current) detection of multidimensional optical signals from single molecules in open junctions

    SciTech Connect

    Agarwalla, Bijay Kumar; Hua, Weijie; Zhang, Yu; Mukamel, Shaul; Harbola, Upendra

    2015-06-07

    The nonlinear optical response of a current-carrying single molecule coupled to two metal leads and driven by a sequence of impulsive optical pulses with controllable phases and time delays is calculated. Coherent (stimulated, heterodyne) detection of photons and incoherent detection of the optically induced current are compared. Using a diagrammatic Liouville space superoperator formalism, the signals are recast in terms of molecular correlation functions which are then expanded in the many-body molecular states. Two dimensional signals in benzene-1,4-dithiol molecule show cross peaks involving charged states. The correlation between optical and charge current signal is also observed.

  19. Detection of Radio Signals with Unknown Duration, Amplitude, and Initial Phase

    NASA Astrophysics Data System (ADS)

    Trifonov, A. P.; Korchagin, Yu. É.; Trifonov, M. V.

    2015-10-01

    We develop the maximum-likelihood algorithm for detecting a radio signal with an arbitrary envelope shape, which is observed against the background of additive Gaussian white noise. The signal duration, amplitude, and initial phase are unknown. The developed algorithm is analyzed on the assumption of sufficiently large signal-to-noise ratios. Asymptotic expressions for the detection-error probabilities are obtained. The developed-algorithm efficiency is checked by computer simulation and the applicability range of the obtained asymptotic expressions for the algorithm characteristics is determined.

  20. A Real-time Auto-detection Method for Random Telegraph Signal (RTS) Noise Detection in CMOS Active pixel sensors

    NASA Astrophysics Data System (ADS)

    Zheng, R.; Zhao, R.; Ma, Y.; Li, B.; Wei, X.; Wang, J.; Gao, W.; Wei, T.; Gao, D.; Hu, Y.

    2015-07-01

    CMOS Active pixel sensors (CMOS APS) are attractive for use in the innermost layers of charged particle trackers, due to their good tradeoffs among the key performances. However, CMOS APS can be greatly influenced by random telegraph signal (RTS) noise, which can cause particle tracking or energy calculation failures. In-depth research of pixels' RTS behavior stimulates the interest of the methods for RTS noise detection, reconstruction and parameters extraction. In this paper, a real-time auto-detection method is proposed, using real-time Gaussian noise standard deviation as the detection threshold. Experimental results show that, compared with current methods using signal standard deviation as the thresholds, the proposed method is more sensitive in multi-level RTS detection and more effective in the case of RTS noise degradation.

  1. Signal Detection Theory Applied to Helicopter Transmission Diagnostic Thresholds

    NASA Technical Reports Server (NTRS)

    Dempsey, Paula J.; Keller, Jonathan A.; Wade, Daniel R.

    2009-01-01

    Helicopter Health Usage Monitoring Systems (HUMS) have potential for providing data to support increasing the service life of a dynamic mechanical component in the transmission of a helicopter. Data collected can demonstrate the HUMS condition indicator responds to a specific component fault with appropriate alert limits and minimal false alarms. Defining thresholds for specific faults requires a tradeoff between the sensitivity of the condition indicator (CI) limit to indicate damage and the number of false alarms. A method using Receiver Operating Characteristic (ROC) curves to assess CI performance was demonstrated using CI data collected from accelerometers installed on several UH60 Black Hawk and AH64 Apache helicopters and an AH64 helicopter component test stand. Results of the analysis indicate ROC curves can be used to reliably assess the performance of commercial HUMS condition indicators to detect damaged gears and bearings in a helicopter transmission.

  2. Signal Detection Theory Applied to Helicopter Transmission Diagnostic Thresholds

    NASA Technical Reports Server (NTRS)

    Dempsey, Paula J.; Keller, Jonathan A.; Wade, Daniel R.

    2008-01-01

    Helicopter Health Usage Monitoring Systems (HUMS) have potential for providing data to support increasing the service life of a dynamic mechanical component in the transmission of a helicopter. Data collected can demonstrate the HUMS condition indicator responds to a specific component fault with appropriate alert limits and minimal false alarms. Defining thresholds for specific faults requires a tradeoff between the sensitivity of the condition indicator (CI) limit to indicate damage and the number of false alarms. A method using Receiver Operating Characteristic (ROC) curves to assess CI performance was demonstrated using CI data collected from accelerometers installed on several UH60 Black Hawk and AH64 Apache helicopters and an AH64 helicopter component test stand. Results of the analysis indicate ROC curves can be used to reliably assess the performance of commercial HUMS condition indicators to detect damaged gears and bearings in a helicopter transmission.

  3. Dual-Process Theory and Signal-Detection Theory of Recognition Memory

    ERIC Educational Resources Information Center

    Wixted, John T.

    2007-01-01

    Two influential models of recognition memory, the unequal-variance signal-detection model and a dual-process threshold/detection model, accurately describe the receiver operating characteristic, but only the latter model can provide estimates of recollection and familiarity. Such estimates often accord with those provided by the remember-know…

  4. Compressive Sensing of Roller Bearing Faults via Harmonic Detection from Under-Sampled Vibration Signals.

    PubMed

    Tang, Gang; Hou, Wei; Wang, Huaqing; Luo, Ganggang; Ma, Jianwei

    2015-10-09

    The Shannon sampling principle requires substantial amounts of data to ensure the accuracy of on-line monitoring of roller bearing fault signals. Challenges are often encountered as a result of the cumbersome data monitoring, thus a novel method focused on compressed vibration signals for detecting roller bearing faults is developed in this study. Considering that harmonics often represent the fault characteristic frequencies in vibration signals, a compressive sensing frame of characteristic harmonics is proposed to detect bearing faults. A compressed vibration signal is first acquired from a sensing matrix with information preserved through a well-designed sampling strategy. A reconstruction process of the under-sampled vibration signal is then pursued as attempts are conducted to detect the characteristic harmonics from sparse measurements through a compressive matching pursuit strategy. In the proposed method bearing fault features depend on the existence of characteristic harmonics, as typically detected directly from compressed data far before reconstruction completion. The process of sampling and detection may then be performed simultaneously without complete recovery of the under-sampled signals. The effectiveness of the proposed method is validated by simulations and experiments.

  5. SETI: The transmission rate of radio communication and the signal's detection

    NASA Astrophysics Data System (ADS)

    Fridman, P. A.

    2011-11-01

    The transmission rate of communication between radio telescopes on Earth and extraterrestrial intelligence (ETI) is here calculated up to distances of 1000 light years. Both phase-shift keying (PSK) and frequency-shift keying (FSK) modulation schemes are considered. It is shown that M-ary FSK is advantageous in terms of energy. Narrow-band pulses scattered over the spectrum sharing a common drift rate can be the probable signals of ETI. Modern SETI spectrum analyzers are well suited to searching for these types of signals. Such signals can be detected using the Hough transform which is a dedicated tool for detecting patterns in an image. The time-frequency plane representing the power output of the spectrum analyzer during the search for ETI gives an image from which the Hough transform (HT) can detect signal patterns with frequency drift.

  6. A feasibility assessment of automated FISH image and signal analysis to assist cervical cancer detection

    NASA Astrophysics Data System (ADS)

    Wang, Xingwei; Li, Yuhua; Liu, Hong; Li, Shibo; Zhang, Roy R.; Zheng, Bin

    2012-02-01

    Fluorescence in situ hybridization (FISH) technology provides a promising molecular imaging tool to detect cervical cancer. Since manual FISH analysis is difficult, time-consuming, and inconsistent, the automated FISH image scanning systems have been developed. Due to limited focal depth of scanned microscopic image, a FISH-probed specimen needs to be scanned in multiple layers that generate huge image data. To improve diagnostic efficiency of using automated FISH image analysis, we developed a computer-aided detection (CAD) scheme. In this experiment, four pap-smear specimen slides were scanned by a dual-detector fluorescence image scanning system that acquired two spectrum images simultaneously, which represent images of interphase cells and FISH-probed chromosome X. During image scanning, once detecting a cell signal, system captured nine image slides by automatically adjusting optical focus. Based on the sharpness index and maximum intensity measurement, cells and FISH signals distributed in 3-D space were projected into a 2-D con-focal image. CAD scheme was applied to each con-focal image to detect analyzable interphase cells using an adaptive multiple-threshold algorithm and detect FISH-probed signals using a top-hat transform. The ratio of abnormal cells was calculated to detect positive cases. In four scanned specimen slides, CAD generated 1676 con-focal images that depicted analyzable cells. FISH-probed signals were independently detected by our CAD algorithm and an observer. The Kappa coefficients for agreement between CAD and observer ranged from 0.69 to 1.0 in detecting/counting FISH signal spots. The study demonstrated the feasibility of applying automated FISH image and signal analysis to assist cyto-geneticists in detecting cervical cancers.

  7. Parameter-induced stochastic resonance based on spectral entropy and its application to weak signal detection.

    PubMed

    Zhang, Jinjing; Zhang, Tao

    2015-02-01

    The parameter-induced stochastic resonance based on spectral entropy (PSRSE) method is introduced for the detection of a very weak signal in the presence of strong noise. The effect of stochastic resonance on the detection is optimized using parameters obtained in spectral entropy analysis. Upon processing employing the PSRSE method, the amplitude of the weak signal is enhanced and the noise power is reduced, so that the frequency of the signal can be estimated with greater precision through spectral analysis. While the improvement in the signal-to-noise ratio is similar to that obtained using the Duffing oscillator algorithm, the computational cost reduces from O(N(2)) to O(N). The PSRSE approach is applied to the frequency measurement of a weak signal made by a vortex flow meter. The results are compared with those obtained applying the Duffing oscillator algorithm. PMID:25725879

  8. Parameter-induced stochastic resonance based on spectral entropy and its application to weak signal detection

    SciTech Connect

    Zhang, Jinjing; Zhang, Tao

    2015-02-15

    The parameter-induced stochastic resonance based on spectral entropy (PSRSE) method is introduced for the detection of a very weak signal in the presence of strong noise. The effect of stochastic resonance on the detection is optimized using parameters obtained in spectral entropy analysis. Upon processing employing the PSRSE method, the amplitude of the weak signal is enhanced and the noise power is reduced, so that the frequency of the signal can be estimated with greater precision through spectral analysis. While the improvement in the signal-to-noise ratio is similar to that obtained using the Duffing oscillator algorithm, the computational cost reduces from O(N{sup 2}) to O(N). The PSRSE approach is applied to the frequency measurement of a weak signal made by a vortex flow meter. The results are compared with those obtained applying the Duffing oscillator algorithm.

  9. Robust off-line heartbeat detection using ECG and pressure-signals.

    PubMed

    Hoeben, Bart; Teo, Soo Kng; Yang, Bo; Su, Yi

    2016-01-01

    Artefacts in pressure- and ECG-signals generally arise due to different causes. Therefore, the combined analysis of both signals can increase the effectiveness of heartbeat detection compared to analysis using solely ECG-signals. In this paper, we present an algorithm for heartbeat annotation by combining the analysis of both the pressure- and ECG-signals. The novelties of our algorithm are as follows: (1) development of a new approach for annotating heartbeats using pressure-signals, (2) development of a mechanism that identifies and corrects paced rhythms, and (3) development of a noise detection approach. Our algorithm is tested on the datasets from the extended phase of the Physionet CINC-2014 challenge and produces an overall score of 87.31%. Finally, we put forth several recommendations that could further improve our algorithm.

  10. Parameter-induced stochastic resonance based on spectral entropy and its application to weak signal detection.

    PubMed

    Zhang, Jinjing; Zhang, Tao

    2015-02-01

    The parameter-induced stochastic resonance based on spectral entropy (PSRSE) method is introduced for the detection of a very weak signal in the presence of strong noise. The effect of stochastic resonance on the detection is optimized using parameters obtained in spectral entropy analysis. Upon processing employing the PSRSE method, the amplitude of the weak signal is enhanced and the noise power is reduced, so that the frequency of the signal can be estimated with greater precision through spectral analysis. While the improvement in the signal-to-noise ratio is similar to that obtained using the Duffing oscillator algorithm, the computational cost reduces from O(N(2)) to O(N). The PSRSE approach is applied to the frequency measurement of a weak signal made by a vortex flow meter. The results are compared with those obtained applying the Duffing oscillator algorithm.

  11. Efficient signal processing for time-resolved fluorescence detection of nitrogen-vacancy spins in diamond

    NASA Astrophysics Data System (ADS)

    Gupta, A.; Hacquebard, L.; Childress, L.

    2016-03-01

    Room-temperature fluorescence detection of the nitrogen-vacancy center electronic spin typically has low signal to noise, requiring long experiments to reveal an averaged signal. Here, we present a simple approach to analysis of time-resolved fluorescence data that permits an improvement in measurement precision through signal processing alone. Applying our technique to experimental data reveals an improvement in signal to noise equivalent to a 14% increase in photon collection efficiency. We further explore the dependence of the signal to noise ratio on excitation power, and analyze our results using a rate equation model. Our results provide a rubric for optimizing fluorescence spin detection, which has direct implications for improving precision of nitrogen-vacancy-based sensors.

  12. Modelling of polysomnographic respiratory measurements for artefact detection and signal restoration.

    PubMed

    Rathnayake, S I; Abeyratne, U R; Hukins, C; Duce, B

    2008-09-01

    Polysomnography (PSG), which incorporates measures of sleep with measures of EEG arousal, air flow, respiratory movement and oxygenation, is universally regarded as the reference standard in diagnosing sleep-related respiratory diseases such as obstructive sleep apnoea syndrome. Over 15 channels of physiological signals are measured from a subject undergoing a typical overnight PSG session. The signals often suffer from data losses, interferences and artefacts. In a typical sleep scoring session, artefact-corrupted signal segments are visually detected and removed from further consideration. This is a highly time-consuming process, and subjective judgement is required for the job. During typical sleep scoring sessions, the target is the detection of segments of diagnostic interest, and signal restoration is not utilized for distorted segments. In this paper, we propose a novel framework for artefact detection and signal restoration based on the redundancy among respiratory flow signals. We focus on the air flow (thermistor sensors) and nasal pressure signals which are clinically significant in detecting respiratory disturbances. The method treats the respiratory system and other organs that provide respiratory-related inputs/outputs to it (e.g., cardiovascular, brain) as a possibly nonlinear coupled-dynamical system, and uses the celebrated Takens embedding theorem as the theoretical basis for signal prediction. Nonlinear prediction across time (self-prediction) and signals (cross-prediction) provides us with a mechanism to detect artefacts as unexplained deviations. In addition to detection, the proposed method carries the potential to correct certain classes of artefacts and restore the signal. In this study, we categorize commonly occurring artefacts and distortions in air flow and nasal pressure measurements into several groups and explore the efficacy of the proposed technique in detecting/recovering them. The results we obtained from a database of clinical

  13. Cortical cholinergic signaling controls the detection of cues

    PubMed Central

    Gritton, Howard J.; Howe, William M.; Mallory, Caitlin S.; Hetrick, Vaughn L.; Berke, Joshua D.; Sarter, Martin

    2016-01-01

    The cortical cholinergic input system has been described as a neuromodulator system that influences broadly defined behavioral and brain states. The discovery of phasic, trial-based increases in extracellular choline (transients), resulting from the hydrolysis of newly released acetylcholine (ACh), in the cortex of animals reporting the presence of cues suggests that ACh may have a more specialized role in cognitive processes. Here we expressed channelrhodopsin or halorhodopsin in basal forebrain cholinergic neurons of mice with optic fibers directed into this region and prefrontal cortex. Cholinergic transients, evoked in accordance with photostimulation parameters determined in vivo, were generated in mice performing a task necessitating the reporting of cue and noncue events. Generating cholinergic transients in conjunction with cues enhanced cue detection rates. Moreover, generating transients in noncued trials, where cholinergic transients normally are not observed, increased the number of invalid claims for cues. Enhancing hits and generating false alarms both scaled with stimulation intensity. Suppression of endogenous cholinergic activity during cued trials reduced hit rates. Cholinergic transients may be essential for synchronizing cortical neuronal output driven by salient cues and executing cue-guided responses. PMID:26787867

  14. Novel method for detection of Sleep Apnoea using respiration signals.

    PubMed

    Carmes, Kristine; Kempfner, Lykke; Sorensen, Helge Bjarup Dissing; Jennum, Poul

    2014-01-01

    Polysomnography (PSG) studies are considered the "gold standard" for the diagnosis of Sleep Apnoea (SA). Identifying cessations of breathing from long-lasting PSG recordings manually is a labour-intensive and time-consuming task for sleep specialist, associated with inter-scorer variability. In this study a simplified, semi-automatic, three-channel method for detection of SA patients is proposed in order to increase analysis reliability and diagnostic accuracy in the clinic. The method is based on characteristic features, such as respiration stoppages pr. hour and the total number of oxygen desaturations > 3%, extracted from the thorax and abdomen respiration effort belts, and the oxyhemoglobin saturation (SaO2), fed to an Elastic Net classifier and validated according to American Academy of Sleep Medicine (AASM) using the patients' AHI value. The method was applied to 109 patient recordings and resulted in a very high SA classification with accuracy of 97.9%. The proposed method reduce the time spent on manual analysis of respiration stoppages and the inter- and intra-scorer variability, and may serve as an alternative screening method for SA. PMID:25569946

  15. Factors Affecting the Timing of Signal Detection of Adverse Drug Reactions.

    PubMed

    Hashiguchi, Masayuki; Imai, Shungo; Uehara, Keiko; Maruyama, Junya; Shimizu, Mikiko; Mochizuki, Mayumi

    2015-01-01

    We investigated factors affecting the timing of signal detection by comparing variations in reporting time of known and unknown ADRs after initial drug release in the USA. Data on adverse event reactions (AERs) submitted to U.S. FDA was used. Six ADRs associated with 6 drugs (rosuvastatin, aripiprazole, teriparatide, telithromycin, exenatide, varenicline) were investigated: Changes in the proportional reporting ratio, reporting odds ratio, and information component as indexes of signal detection were followed every 3 months after each drugs release, and the time for detection of signals was investigated. The time for the detection of signal to be detected after drug release in the USA was 2-10 months for known ADRs and 19-44 months for unknown ones. The median lag time for known and unknown ADRs was 99.0-122.5 days and 185.5-306.0 days, respectively. When the FDA released advisory information on rare but potentially serious health risks of an unknown ADR, the time lag to report from the onset of ADRs to the FDA was shorter. This study suggested that one factor affecting signal detection time is whether an ADR was known or unknown at release. PMID:26641634

  16. The real-time realization of detecting weak multi-pulse laser echo signal

    NASA Astrophysics Data System (ADS)

    Zhang, Tinghua; Fan, Guihua; Sun, Huayan

    2014-12-01

    The multi-pulsed laser ranging technology is prominent on improving the maximum measuring range of laser active detection,laser range finder and other long-distance measurement. For all laser echo detection techniques, the weak signal detection is an important step, which aims to increase the detection range. Most algorithms are based on the priori knowledge of laser echo or the improvement of laser power. However, we cannot know or estimate the waveform accurately in many applications. Moreover, these means are difficult to satisfy the real-time needs. The present paper proposes an improved algorithm which extended the signal accumulation algorithm for the high power burst laser. This method is mainly based on signal accumulation and tri-cumulant algorithm which can improve the signal to noise SNR of the weak laser echo; moreover it does not need more prior knowledge of echo. In order to reduce the detection time, the algorithm is realized based on FPGA using signal retiming and parallel pipeline structure. The simulations and experiments results demonstrate that the minimum detecting SNR is -5dB and the maximum detecting time is only less than 1us.

  17. Tables of square-law signal detection statistics for Hann spectra with 50 percent overlap

    NASA Technical Reports Server (NTRS)

    Deans, Stanley R.; Cullers, D. Kent

    1991-01-01

    The Search for Extraterrestrial Intelligence, currently being planned by NASA, will require that an enormous amount of data be analyzed in real time by special purpose hardware. It is expected that overlapped Hann data windows will play an important role in this analysis. In order to understand the statistical implication of this approach, it has been necessary to compute detection statistics for overlapped Hann spectra. Tables of signal detection statistics are given for false alarm rates from 10(exp -14) to 10(exp -1) and signal detection probabilities from 0.50 to 0.99; the number of computed spectra ranges from 4 to 2000.

  18. Ground detection of terrestrial gamma ray flashes from distant radio signals

    NASA Astrophysics Data System (ADS)

    Lyu, Fanchao; Cummer, Steven A.; Briggs, Michael; Marisaldi, Martino; Blakeslee, Richard J.; Bruning, Eric; Wilson, Jennifer G.; Rison, William; Krehbiel, Paul; Lu, Gaopeng; Cramer, Eric; Fitzpatrick, Gerard; Mailyan, Bagrat; McBreen, Sheila; Roberts, Oliver J.; Stanbro, Matthew

    2016-08-01

    Terrestrial gamma ray flashes (TGFs) are brief bursts of energetic gammy-ray photons generated during thunderstorms, which have been detected almost exclusively by satellite-based instruments. Here we present three lines of evidence which includes the three out of three simultaneously observed pairs, the same occurrence contexts, and the consistent estimated occurrence rate, which indicate a direct relationship between a subset of TGFs and a class of energetic radio signal easily detectable by ground-based sensors. This connection indicates that these gamma ray and radio emissions are two views of the same phenomenon and further enable detection of these TGFs from ground distant radio signals alone. Besides dramatically increasing the detection rate of TGFs, this ground detection approach can identify TGFs in continental and coastal areas that are at latitudes too high for present TGF-detecting satellites and will provide more insights into the mechanism of TGF production.

  19. The detection of cavitation in hydraulic machines by use of ultrasonic signal analysis

    NASA Astrophysics Data System (ADS)

    Gruber, P.; Odermatt, P.; Etterlin, M.; Lerch, T.; Frei, M.; Farhat, M.

    2014-03-01

    This presentation describes an experimental approach for the detection of cavitation in hydraulic machines by use of ultrasonic signal analysis. Instead of using the high frequency pulses (typically 1MHz) only for transit time measurement different other signal characteristics are extracted from the individual signals and its correlation function with reference signals in order to gain knowledge of the water conditions. As the pulse repetition rate is high (typically 100Hz), statistical parameters can be extracted of the signals. The idea is to find patterns in the parameters by a classifier that can distinguish between the different water states. This classification scheme has been applied to different cavitation sections: a sphere in a water flow in circular tube at the HSLU in Lucerne, a NACA profile in a cavitation tunnel and a Francis model test turbine both at LMH in Lausanne. From the signal raw data several statistical parameters in the time and frequency domain as well as from the correlation function with reference signals have been determined. As classifiers two methods were used: neural feed forward networks and decision trees. For both classification methods realizations with lowest complexity as possible are of special interest. It is shown that three signal characteristics, two from the signal itself and one from the correlation function are in many cases sufficient for the detection capability. The final goal is to combine these results with operating point, vibration, acoustic emission and dynamic pressure information such that a distinction between dangerous and not dangerous cavitation is possible.

  20. Reducing false arrhythmia alarms in the ICU using multimodal signals and robust QRS detection.

    PubMed

    Sadr, Nadi; Huvanandana, Jacqueline; Nguyen, Doan Trang; Kalra, Chandan; McEwan, Alistair; de Chazal, Philip

    2016-08-01

    This study developed algorithms to decrease the arrhythmia false alarms in the ICU by processing multimodal signals of photoplethysmography (PPG), arterial blood pressure (ABP), and two ECG signals. The goal was to detect the five critical arrhythmias comprising asystole (ASY), extreme bradycardia (EBR), extreme tachycardia (ETC), ventricular tachycardia (VTA), and ventricular flutter or fibrillation (VFB). The different characteristics of the arrhythmias suggested the application of individual signal processing for each alarm and the combination of the algorithms to enhance false alarm detection. Thus, different features and signal processing techniques were used for each arrhythmia type. The ECG signals were first processed to reduce the signal interference. Then, a Hilbert-transform based QRS detector algorithm was utilized to identify the QRS complexes, which were then processed to determine the instantaneous heart rate. The pulsatile signals (PPG and ABP) were processed to discover the pulse onset of beats which were then employed to measure the heart rate. The signal quality index (SQI) of the signals was implemented to verify the integrity of the heart rate information. The overall score obtained by our algorithms in the 2015 Computing in Cardiology Challenge was a score of 74.03% for retrospective and 69.92% for real-time analysis. PMID:27455121

  1. Climate signal detected in sub-fossil and living oak trees data. An analysis of signal frequency components

    NASA Astrophysics Data System (ADS)

    Constantin, Nechita; Francisca, Chiriloaei; Maria, Radoane; Ionel, Popa; Nicoae, Radoane

    2016-04-01

    This study is focused on analysis the frequency components of the signal detected in living and sub-fossil tree ring series from different time periods. The investigation is oriented to analyze signal frequency components (low and high) of the two categories of trees. The interpretation technique of tree ring width is the instrument most often used to elaborate past climatic reconstructions. The annual resolution, but also, the high capacity of trees to accumulate climatic information are attributes which confer to palaeo-environmental reconstructions the biggest credibility. The main objective of the study refers to the evaluation of climatic signal characteristics, both present day climate and palaeo-climate (last 7000 years BP). Modern dendrochronological methods were applied on 350 samples of sub-fossil trees and 400 living trees. The subfossil trunks were sampled from different fluvial environments (Siret, Suceava, Moldova). Their age was determined using radiocarbon, varying from under 100 years to almost 7000 years BP. The subfossil tree species investigated were Quercus, Alnus, Ulmus. Considering living trees, these were identified on eastern part of Romania, in different actual physico-geographical conditions. The studied living tree species consisted in Quercus species (robur and petraea). Each site was investigated regarding stress factors of the sampled tree. The working methods were applied to the total wood series, both late and early, to detect intra-annual level climate information. Each series has been tested to separate individual trees with climatic signal of other trees with different signals (noises determined by competition between individuals or site stress, or anthropic impact). Comparing dendrochronological series (sub-fossil and living trees) we want to identify what significant causes determined the difference in the signal frequencies. Especially, the human interventions registered in the last 2 centuries will be evaluated by these

  2. Speech Perception in Noise in Normally Hearing Children: Does Binaural Frequency Modulated Fitting Provide More Benefit than Monaural Frequency Modulated Fitting?

    PubMed

    Mukari, Siti Zamratol-Mai Sarah; Umat, Cila; Razak, Ummu Athiyah Abdul

    2011-07-01

    The aim of the present study was to compare the benefit of monaural versus binaural ear-level frequency modulated (FM) fitting on speech perception in noise in children with normal hearing. Reception threshold for sentences (RTS) was measured in no-FM, monaural FM, and binaural FM conditions in 22 normally developing children with bilateral normal hearing, aged 8 to 9 years old. Data were gathered using the Pediatric Malay Hearing in Noise Test (P-MyHINT) with speech presented from front and multi-talker babble presented from 90°, 180°, 270° azimuths in a sound treated booth. The results revealed that the use of either monaural or binaural ear level FM receivers provided significantly better mean RTSs than the no-FM condition (P<0.001). However, binaural FM did not produce a significantly greater benefit in mean RTS than monaural fitting. The benefit of binaural over monaural FM varies across individuals; while binaural fitting provided better RTSs in about 50% of study subjects, there were those in whom binaural fitting resulted in either deterioration or no additional improvement compared to monaural FM fitting. The present study suggests that the use of monaural ear-level FM receivers in children with normal hearing might provide similar benefit as binaural use. Individual subjects' variations of binaural FM benefit over monaural FM suggests that the decision to employ monaural or binaural fitting should be individualized. It should be noted however, that the current study recruits typically developing normal hearing children. Future studies involving normal hearing children with high risk of having difficulty listening in noise is indicated to see if similar findings are obtained. PMID:26557323

  3. Auditory driving of the autonomic nervous system: Listening to theta-frequency binaural beats post-exercise increases parasympathetic activation and sympathetic withdrawal

    PubMed Central

    McConnell, Patrick A.; Froeliger, Brett; Garland, Eric L.; Ives, Jeffrey C.; Sforzo, Gary A.

    2014-01-01

    Binaural beats are an auditory illusion perceived when two or more pure tones of similar frequencies are presented dichotically through stereo headphones. Although this phenomenon is thought to facilitate state changes (e.g., relaxation), few empirical studies have reported on whether binaural beats produce changes in autonomic arousal. Therefore, the present study investigated the effects of binaural beating on autonomic dynamics [heart rate variability (HRV)] during post-exercise relaxation. Subjects (n = 21; 18–29 years old) participated in a double-blind, placebo-controlled study during which binaural beats and placebo were administered over two randomized and counterbalanced sessions (within-subjects repeated-measures design). At the onset of each visit, subjects exercised for 20-min; post-exercise, subjects listened to either binaural beats (‘wide-band’ theta-frequency binaural beats) or placebo (carrier tones) for 20-min while relaxing alone in a quiet, low-light environment. Dependent variables consisted of high-frequency (HF, reflecting parasympathetic activity), low-frequency (LF, reflecting sympathetic and parasympathetic activity), and LF/HF normalized powers, as well as self-reported relaxation. As compared to the placebo visit, the binaural-beat visit resulted in greater self-reported relaxation, increased parasympathetic activation and increased sympathetic withdrawal. By the end of the 20-min relaxation period there were no observable differences in HRV between binaural-beat and placebo visits, although binaural-beat associated HRV significantly predicted subsequent reported relaxation. Findings suggest that listening to binaural beats may exert an acute influence on both LF and HF components of HRV and may increase subjective feelings of relaxation. PMID:25452734

  4. The correct estimate of the probability of false detection of the matched filter in weak-signal detection problems

    NASA Astrophysics Data System (ADS)

    Vio, R.; Andreani, P.

    2016-05-01

    The reliable detection of weak signals is a critical issue in many astronomical contexts and may have severe consequences for determining number counts and luminosity functions, but also for optimizing the use of telescope time in follow-up observations. Because of its optimal properties, one of the most popular and widely-used detection technique is the matched filter (MF). This is a linear filter designed to maximise the detectability of a signal of known structure that is buried in additive Gaussian random noise. In this work we show that in the very common situation where the number and position of the searched signals within a data sequence (e.g. an emission line in a spectrum) or an image (e.g. a point-source in an interferometric map) are unknown, this technique, when applied in its standard form, may severely underestimate the probability of false detection. This is because the correct use of the MF relies upon a priori knowledge of the position of the signal of interest. In the absence of this information, the statistical significance of features that are actually noise is overestimated and detections claimed that are actually spurious. For this reason, we present an alternative method of computing the probability of false detection that is based on the probability density function (PDF) of the peaks of a random field. It is able to provide a correct estimate of the probability of false detection for the one-, two- and three-dimensional case. We apply this technique to a real two-dimensional interferometric map obtained with ALMA.

  5. Sound-by-sound thalamic stimulation modulates midbrain auditory excitability and relative binaural sensitivity in frogs.

    PubMed

    Ponnath, Abhilash; Farris, Hamilton E

    2014-01-01

    Descending circuitry can modulate auditory processing, biasing sensitivity to particular stimulus parameters and locations. Using awake in vivo single unit recordings, this study tested whether electrical stimulation of the thalamus modulates auditory excitability and relative binaural sensitivity in neurons of the amphibian midbrain. In addition, by using electrical stimuli that were either longer than the acoustic stimuli (i.e., seconds) or presented on a sound-by-sound basis (ms), experiments addressed whether the form of modulation depended on the temporal structure of the electrical stimulus. Following long duration electrical stimulation (3-10 s of 20 Hz square pulses), excitability (spikes/acoustic stimulus) to free-field noise stimuli decreased by 32%, but returned over 600 s. In contrast, sound-by-sound electrical stimulation using a single 2 ms duration electrical pulse 25 ms before each noise stimulus caused faster and varied forms of modulation: modulation lasted <2 s and, in different cells, excitability either decreased, increased or shifted in latency. Within cells, the modulatory effect of sound-by-sound electrical stimulation varied between different acoustic stimuli, including for different male calls, suggesting modulation is specific to certain stimulus attributes. For binaural units, modulation depended on the ear of input, as sound-by-sound electrical stimulation preceding dichotic acoustic stimulation caused asymmetric modulatory effects: sensitivity shifted for sounds at only one ear, or by different relative amounts for both ears. This caused a change in the relative difference in binaural sensitivity. Thus, sound-by-sound electrical stimulation revealed fast and ear-specific (i.e., lateralized) auditory modulation that is potentially suited to shifts in auditory attention during sound segregation in the auditory scene.

  6. MAP Support Detection for Greedy Sparse Signal Recovery Algorithms in Compressive Sensing

    NASA Astrophysics Data System (ADS)

    Lee, Namyoon

    2016-10-01

    A reliable support detection is essential for a greedy algorithm to reconstruct a sparse signal accurately from compressed and noisy measurements. This paper proposes a novel support detection method for greedy algorithms, which is referred to as "\\textit{maximum a posteriori (MAP) support detection}". Unlike existing support detection methods that identify support indices with the largest correlation value in magnitude per iteration, the proposed method selects them with the largest likelihood ratios computed under the true and null support hypotheses by simultaneously exploiting the distributions of sensing matrix, sparse signal, and noise. Leveraging this technique, MAP-Matching Pursuit (MAP-MP) is first presented to show the advantages of exploiting the proposed support detection method, and a sufficient condition for perfect signal recovery is derived for the case when the sparse signal is binary. Subsequently, a set of iterative greedy algorithms, called MAP-generalized Orthogonal Matching Pursuit (MAP-gOMP), MAP-Compressive Sampling Matching Pursuit (MAP-CoSaMP), and MAP-Subspace Pursuit (MAP-SP) are presented to demonstrate the applicability of the proposed support detection method to existing greedy algorithms. From empirical results, it is shown that the proposed greedy algorithms with highly reliable support detection can be better, faster, and easier to implement than basis pursuit via linear programming.

  7. High Speed All Optical Nyquist Signal Generation and Full-band Coherent Detection

    PubMed Central

    Zhang, Junwen; Yu, Jianjun; Fang, Yuan; Chi, Nan

    2014-01-01

    Spectrum efficient data transmission is of key interest for high capacity optical communication systems considering the limited available bandwidth. Transmission of the high speed signal with higher-order modulation formats within the Nyquist bandwidth using coherent detection brings attractive performance advantages. However, high speed Nyquist signal generation with high order modulation formats is challenging. Electrical Nyquist pulse generation is restricted by the limited sampling rate and processor capacities of digital-to-analog convertor devices, while the optical Nyquist signals can provide a much higher symbol rate using time domain multiplexing method. However, most optical Nyquist signals are based on direct detection with simple modulation formats. Here we report the first experimental demonstration of high speed all optical Nyquist signal generation based on Sinc-shaped pulse generation and time-division multiplexing with high level modulation format and full-band coherent detection. Our experiments demonstrate a highly flexible and compatible all optical high speed Nyquist signal generation and detection scheme for future fiber communication systems. PMID:25142269

  8. High speed all optical Nyquist signal generation and full-band coherent detection.

    PubMed

    Zhang, Junwen; Yu, Jianjun; Fang, Yuan; Chi, Nan

    2014-08-21

    Spectrum efficient data transmission is of key interest for high capacity optical communication systems considering the limited available bandwidth. Transmission of the high speed signal with higher-order modulation formats within the Nyquist bandwidth using coherent detection brings attractive performance advantages. However, high speed Nyquist signal generation with high order modulation formats is challenging. Electrical Nyquist pulse generation is restricted by the limited sampling rate and processor capacities of digital-to-analog convertor devices, while the optical Nyquist signals can provide a much higher symbol rate using time domain multiplexing method. However, most optical Nyquist signals are based on direct detection with simple modulation formats. Here we report the first experimental demonstration of high speed all optical Nyquist signal generation based on Sinc-shaped pulse generation and time-division multiplexing with high level modulation format and full-band coherent detection. Our experiments demonstrate a highly flexible and compatible all optical high speed Nyquist signal generation and detection scheme for future fiber communication systems.

  9. Teager–Kaiser energy operator signal conditioning improves EMG onset detection

    PubMed Central

    Rider, Patrick; Steinweg, Ken; DeVita, Paul; Hortobágyi, Tibor

    2010-01-01

    Accurate identification of the onset of muscle activity is an important element in the biomechanical analysis of human movement. The purpose of this study was to determine if inclusion of the Teager–Kaiser energy operator (TKEO) in signal conditioning would increase the accuracy of popular electromyography (EMG) onset detection methods. Three methods, visual determination, threshold-based method, and approximated generalized likelihood ratio were used to estimate the onset of EMG burst with and without TKEO conditioning. Reference signals, with known onset times, were constructed from EMG signals collected during isometric contraction of the vastus lateralis (n = 17). Additionally, vastus lateralis EMG signals (n = 255) recorded during gait were used to evaluate a clinical application of the TKEO conditioning. Inclusion of TKEO in signal conditioning significantly reduced mean detection error of all three methods compared with signal conditioning without TKEO, using artificially generated reference data (13 vs. 98 ms, p < 0.001) and also compared with experimental data collected during gait (55 vs. 124 ms, p < 0.001). In conclusion, addition of TKEO as a step in conditioning surface EMG signals increases the detection accuracy of EMG burst boundaries. PMID:20526612

  10. Study of Signal Detection, Integration, and Propagation in Quorum Sensing at the Single Cell Level

    NASA Astrophysics Data System (ADS)

    Long, Tao; Bassler, Bonnie; Wingreen, Ned

    2007-03-01

    Bacteria respond to their environment and to each other and accordingly adjust their gene-expression levels. Accurate signal detection, appropriate signal integration, and faithful signal propagation are essential for a cell to make correct adjustments in response to various extracellular cues. To better understand this information processing by living cells, we studied a model system -- the quorum-sensing circuit in Vibrio harveyi. Quorum sensing is a process in which bacteria communicate with each other by diffusible chemical molecules, termed ``autoinducers'', to commit to coordinated developmental decisions. Three types of autoinducers are detected coincidently by three parallel receptors. The signals are then integrated into the same signaling pathway and propagated by phosphorylation or dephosphorylation of the pathway components. To quantitatively measure the intracellular response, we applied a fluorescent protein reporter, whose production is regulated by a phosphorylated protein in the pathway. By single-cell microscopy, we can explore features of this information-processing circuit such as coincidence detection, signal integration, noise reduction or filtering, and especially the fidelity in signal processing achieved in the presence of inevitable fluctuations.

  11. An Obstructive Sleep Apnea Detection Approach Using a Discriminative Hidden Markov Model From ECG Signals.

    PubMed

    Song, Changyue; Liu, Kaibo; Zhang, Xi; Chen, Lili; Xian, Xiaochen

    2016-07-01

    Obstructive sleep apnea (OSA) syndrome is a common sleep disorder suffered by an increasing number of people worldwide. As an alternative to polysomnography (PSG) for OSA diagnosis, the automatic OSA detection methods used in the current practice mainly concentrate on feature extraction and classifier selection based on collected physiological signals. However, one common limitation in these methods is that the temporal dependence of signals are usually ignored, which may result in critical information loss for OSA diagnosis. In this study, we propose a novel OSA detection approach based on ECG signals by considering temporal dependence within segmented signals. A discriminative hidden Markov model (HMM) and corresponding parameter estimation algorithms are provided. In addition, subject-specific transition probabilities within the model are employed to characterize the subject-to-subject differences of potential OSA patients. To validate our approach, 70 recordings obtained from the Physionet Apnea-ECG database were used. Accuracies of 97.1% for per-recording classification and 86.2% for per-segment OSA detection with satisfactory sensitivity and specificity were achieved. Compared with other existing methods that simply ignore the temporal dependence of signals, the proposed HMM-based detection approach delivers more satisfactory detection performance and could be extended to other disease diagnosis applications. PMID:26560867

  12. A comparison of signal detection theory to the objective threshold/strategic model of unconscious perception.

    PubMed

    Haase, Steven J; Fisk, Gary D

    2011-08-01

    A key problem in unconscious perception research is ruling out the possibility that weak conscious awareness of stimuli might explain the results. In the present study, signal detection theory was compared with the objective threshold/strategic model as explanations of results for detection and identification sensitivity in a commonly used unconscious perception task. In the task, 64 undergraduate participants detected and identified one of four briefly displayed, visually masked letters. Identification was significantly above baseline (i.e., proportion correct > .25) at the highest detection confidence rating. This result is most consistent with signal detection theory's continuum of sensory states and serves as a possible index of conscious perception. However, there was limited support for the other model in the form of a predicted "looker's inhibition" effect, which produced identification performance that was significantly below baseline. One additional result, an interaction between the target stimulus and type of mask, raised concerns for the generality of unconscious perception effects.

  13. Unsupervised Event Characterization and Detection in Multichannel Signals: An EEG application

    PubMed Central

    Mur, Angel; Dormido, Raquel; Vega, Jesús; Duro, Natividad; Dormido-Canto, Sebastian

    2016-01-01

    In this paper, we propose a new unsupervised method to automatically characterize and detect events in multichannel signals. This method is used to identify artifacts in electroencephalogram (EEG) recordings of brain activity. The proposed algorithm has been evaluated and compared with a supervised method. To this end an example of the performance of the algorithm to detect artifacts is shown. The results show that although both methods obtain similar classification, the proposed method allows detecting events without training data and can also be applied in signals whose events are unknown a priori. Furthermore, the proposed method provides an optimal window whereby an optimal detection and characterization of events is found. The detection of events can be applied in real-time. PMID:27120605

  14. A multiple constrained signal subspace projection for target detection in hyperspectral images

    NASA Astrophysics Data System (ADS)

    Chang, Lena; Wu, Yen-Ting; Tang, Zay-Shing; Chang, Yang-Lang

    2015-05-01

    In the study, we develop a multiple constrained signal subspace projection (SSP) approach to target detection. Instead of using single constraint on target detection, we design an optimal filter with multiple constraints on desired targets by using SSP. The proposed SSP approach fully exploits the orthogonal property of two orthogonal subspaces: one denoted signal subspace containing desired and undesired/background targets; the other denoted noise subspace, which is orthogonal to signal subspace. By projecting the weights of the detection filter on the signal subspace, the proposed SSP can reduces some estimation errors in target signatures and alleviate the performance degradation caused by uncertainty of target signature. The SSP approach can detect desired targets, suppress undesired targets and minimize the interference effects. In experiments, we provide three methods in selecting multiple constraints of the desired target: Kmeans, principal eigenvectors and endmenber extracting techniques. Simulation results show that the proposed SSP with multiple constraints selected by K-means has better detection performance. Furthermore, the proposed SSP with multiple constraints is a robust detection approach which could overcome the uncertainty of desired target signature in real image data.

  15. CD/AuNPs/MWCNTs based electrochemical sensor for quercetin dual-signal detection.

    PubMed

    Kan, Xianwen; Zhang, Tingting; Zhong, Min; Lu, Xiaojing

    2016-03-15

    A dual-signal strategy was developed in the present work for quercetin (QR) electrochemical recognition and detection. Mercapto-β-cyclodextrin (HS-β-CD) self-assembled on gold nanoparticles and multi-walled carbon nanotubes modified electrode surface to fabricate an electrochemical sensor. Scanning electron microscope, electrochemical impedance spectroscopy, and cyclic voltammetry were employed to characterize the preparation process of the sensor. Hydroquinone (HQ) was chosen as an electrochemical marker for QR detection due to its small molecular size for the formation of inclusion with HS-β-CD. The results of UV-vis and differential pulse voltammetry demonstrate that the added QR can replace the included HQ in CD cavities, resulting in the dual-signal in electrochemical experiments composed of the decrease of oxidized current of HQ and the increase of oxidized current of QR. Compared with the sensor for QR detection in the absence of HQ, the sensor based dual-signal strategy exhibited a higher sensitivity with a wider detection range from 5.0 × 10(-9) to 7.0 × 10(-6)mol/L. With good selectivity, reproducibility, and stability, the sensor was applied for real samples detection with satisfactory results. The proposed dual-signal strategy can be readily extended to the selective recognition and sensitive detection of other molecules.

  16. Fractal dimension analysis for spike detection in low SNR extracellular signals

    NASA Astrophysics Data System (ADS)

    Salmasi, Mehrdad; Büttner, Ulrich; Glasauer, Stefan

    2016-06-01

    Objective. Many algorithms have been suggested for detection and sorting of spikes in extracellular recording. Nevertheless, it is still challenging to detect spikes in low signal-to-noise ratios (SNR). We propose a spike detection algorithm that is based on the fractal properties of extracellular signals and can detect spikes in low SNR regimes. Semi-intact spikes are low-amplitude spikes whose shapes are almost preserved. The detection of these spikes can significantly enhance the performance of multi-electrode recording systems. Approach. Semi-intact spikes are simulated by adding three noise components to a spike train: thermal noise, inter-spike noise, and spike-level noise. We show that simulated signals have fractal properties which make them proper candidates for fractal analysis. Then we use fractal dimension as the main core of our spike detection algorithm and call it fractal detector. The performance of the fractal detector is compared with three frequently used spike detectors. Main results. We demonstrate that in low SNR, the fractal detector has the best performance and results in the highest detection probability. It is shown that, in contrast to the other three detectors, the performance of the fractal detector is independent of inter-spike noise power and that variations in spike shape do not alter its performance. Finally, we use the fractal detector for spike detection in experimental data and similar to simulations, it is shown that the fractal detector has the best performance in low SNR regimes. Significance. The detection of low-amplitude spikes provides more information about the neural activity in the vicinity of the recording electrodes. Our results suggest using the fractal detector as a reliable and robust method for detecting semi-intact spikes in low SNR extracellular signals.

  17. Detection of the greenhouse gas signal from space - A progress report

    NASA Technical Reports Server (NTRS)

    Barnett, T. P.; Haskins, R.; Chahine, M.

    1991-01-01

    The spatial distribution of the expected changes in the atmospheric water vapor content and cloud cover, as predicted by the transient greenhouse gas (GHG) simulation of Hansen et al. (1988), are examined to determine whether the signals would be large enough and unique enough to be useful in a GHG detection study. The nature of the predicted GHG signal was first examined using the transient CO2 run from the GISS ocean/atmosphere general circulation model. Next, the remotely sensed irradiance characteristics data (as the measure of water vapor content) supplied by the HIRS/MSU sensors for the area of the equatorial cold tongue region (the region in which there are no measurement stations). It is shown that HIRS/MSU signals can provide data necessary for detecting GHS signals in atmospheric moisture for regions where ground observations are not possible.

  18. Use of multiscale entropy to facilitate artifact detection in electroencephalographic signals.

    PubMed

    Mariani, Sara; Borges, Ana F T; Henriques, Teresa; Goldberger, Ary L; Costa, Madalena D

    2015-01-01

    Electroencephalographic (EEG) signals present a myriad of challenges to analysis, beginning with the detection of artifacts. Prior approaches to noise detection have utilized multiple techniques, including visual methods, independent component analysis and wavelets. However, no single method is broadly accepted, inviting alternative ways to address this problem. Here, we introduce a novel approach based on a statistical physics method, multiscale entropy (MSE) analysis, which quantifies the complexity of a signal. We postulate that noise corrupted EEG signals have lower information content, and, therefore, reduced complexity compared with their noise free counterparts. We test the new method on an open-access database of EEG signals with and without added artifacts due to electrode motion. PMID:26738116

  19. A new algorithm for epilepsy seizure onset detection and spread estimation from EEG signals

    NASA Astrophysics Data System (ADS)

    Quintero-Rincón, Antonio; Pereyra, Marcelo; D'Giano, Carlos; Batatia, Hadj; Risk, Marcelo

    2016-04-01

    Appropriate diagnosis and treatment of epilepsy is a main public health issue. Patients suffering from this disease often exhibit different physical characterizations, which result from the synchronous and excessive discharge of a group of neurons in the cerebral cortex. Extracting this information using EEG signals is an important problem in biomedical signal processing. In this work we propose a new algorithm for seizure onset detection and spread estimation in epilepsy patients. The algorithm is based on a multilevel 1-D wavelet decomposition that captures the physiological brain frequency signals coupled with a generalized gaussian model. Preliminary experiments with signals from 30 epilepsy crisis and 11 subjects, suggest that the proposed methodology is a powerful tool for detecting the onset of epilepsy seizures with his spread across the brain.

  20. Detection and tracking of humans and vehicle targets using high definition television signals in urban areas

    NASA Astrophysics Data System (ADS)

    Greneker, Gene

    2007-04-01

    The detection and tracking of humans and vehicles on the battlefield using radar systems operating at microwave frequencies was first achieved almost 40 years ago. The subsequent generation of radars designed to detect personnel and vehicles on the battlefield has seen improvements due to increased signal processing capability. To date, most of the self-contained human detection radars have incorporated a co-located (monostatic) transmitter and receiver operated by humans. Approximately, three decades ago the bistatic radar was introduced and used for security at high value target sites. These bistatic "fence" radars employ a transmitter located at one end of a bistatic baseline and a receiver at the other end of the baseline. The receiver is tuned to the transmitter. Operation is simple; an intruder crosses the bistatic baseline and is detected after simple signal processing is performed on the bistatic signature produced by the intruder. The experiments demonstrate that passive bistatic radar can be used to detect humans and vehicles. This paper describes "quick-look" experiments that have been conducted in the Atlanta, Georgia area to detect humans and vehicles using a passive radar configuration requiring no coordination between the receiver and transmitter. The illumination source (transmitter) is a High Definition Television (HDTV) broadcast transmitter located approximately 13.5 miles from the test area. The transmitter is broadcasting a 6 MHz wide digital signal with a pilot carrier on a frequency of 548.310 MHz. The continuous wave (CW) pilot carrier HDTV signal component is processed to extract the signature of the walking human or the signature of a vehicle. The experimental receiving system utilizes a commercial off-the-shelf (COTS) communications receiver. A set of multi-element back to back Yagi antennas are used to provide a reference signal and the signal from the area where the human subject is located. The walking human generates micro

  1. Signal detection by human observers: a cutoff reinforcement learning model of categorization decisions under uncertainty.

    PubMed

    Erev, I

    1998-04-01

    Previous experimental examinations of binary categorization decisions have documented robust behavioral regularities that cannot be predicted by signal detection theory (D.M. Green & J.A. Swets, 1966/1988). The present article reviews the known regularities and demonstrates that they can be accounted for by a minimal modification of signal detection theory: the replacement of the "ideal observer" cutoff placement rule with a cutoff reinforcement learning rule. This modification is derived from a cognitive game theoretic analysis (A.E. Roth & I. Erev, 1995). The modified model reproduces all 19 experimental regularities that have been considered. In all cases,it outperforms the original explanations. Some of these previous explanations are based on important concepts such as conservatism, probability matching, and "the gambler's fallacy" that receive new meanings given the current results. Implications for decision-making research and for applications of traditional signal detection theory are discussed.

  2. Signal-on Protein Detection via Dye Translocation between Aptamer and Quantum Dot.

    PubMed

    Lao, Yeh-Hsing; Chi, Chun-Wei; Friedrich, Sarah M; Peck, Konan; Wang, Tza-Huei; Leong, Kam W; Chen, Lin-Chi

    2016-05-18

    A unique interaction between the cyanine dye and negatively charged quantum dot is used to construct a signal-on biaptameric quantum dot (QD) Förster resonance energy transfer (FRET) beacon for protein detection and distinct aptamer characterization. The beacon comprises a pair of aptamers, one intercalated with the cyanine dye (YOYO-3) and the other conjugated to a negatively charged, carboxyl-QD. When the target protein is present, structural folding and sandwich association of the two aptamers take place. As a consequence, YOYO-3 is displaced from the folded aptamer and transferred to the unblocked QD surface to yield a target concentration-dependent FRET signal. As a proof-of-principle, we demonstrate the detection of thrombin ranging from nanomolar to submicromolar concentrations and confirm the dye translocation using cylindrical illumination confocal spectroscopy (CICS). The proposed beacon provides a simple, rapid, signal-on FRET detection for protein as well as a potential platform for distinct aptamer screening.

  3. Pulsed laser noise analysis and pump-probe signal detection with a data acquisition card.

    PubMed

    Werley, Christopher A; Teo, Stephanie M; Nelson, Keith A

    2011-12-01

    A photodiode and data acquisition card whose sampling clock is synchronized to the repetition rate of a laser are used to measure the energy of each laser pulse. Simple analysis of the data yields the noise spectrum from very low frequencies up to half the repetition rate and quantifies the pulse energy distribution. When two photodiodes for balanced detection are used in combination with an optical modulator, the technique is capable of detecting very weak pump-probe signals (ΔI/I(0) ~ 10(-5) at 1 kHz), with a sensitivity that is competitive with a lock-in amplifier. Detection with the data acquisition card is versatile and offers many advantages including full quantification of noise during each stage of signal processing, arbitrary digital filtering in silico after data collection is complete, direct readout of percent signal modulation, and easy adaptation for fast scanning of delay between pump and probe.

  4. Detection of Potential Transit Signals in 17 Quarters of Kepler Mission Data

    NASA Astrophysics Data System (ADS)

    Seader, Shawn; Jenkins, Jon M.; Tenenbaum, Peter; Twicken, Joseph D.; Smith, Jeffrey C.; Morris, Rob; Catanzarite, Joseph; Clarke, Bruce D.; Li, Jie; Cote, Miles T.; Burke, Christopher J.; McCauliff, Sean; Girouard, Forrest R.; Campbell, Jennifer R.; Kamal Uddin, Akm; Zamudio, Khadeejah A.; Sabale, Anima; Henze, Christopher E.; Thompson, Susan E.; Klaus, Todd C.

    2015-03-01

    We present the results of a search for potential transit signals in the full 17-quarter data set collected during Kepler's primary mission that ended on 2013 May 11, due to the on board failure of a second reaction wheel needed to maintain high precision, fixed, pointing. The search includes a total of 198,646 targets, of which 112,001 were observed in every quarter and 86,645 were observed in a subset of the 17 quarters. For the first time, this multi-quarter search is performed on data that have been fully and uniformly reprocessed through the newly released version of the Data Processing Pipeline. We find a total of 12,669 targets that contain at least one signal that meets our detection criteria: periodicity of the signal, a minimum of three transit events, an acceptable signal-to-noise ratio, and four consistency tests that suppress many false positives. Each target containing at least one transit-like pulse sequence is searched repeatedly for other signals that meet the detection criteria, indicating a multiple planet system. This multiple planet search adds an additional 7698 transit-like signatures for a total of 20,367. Comparison of this set of detected signals with a set of known and vetted transiting planet signatures in the Kepler field of view shows that the recovery rate of the search is 90.3%. We review ensemble properties of the detected signals and present various metrics useful in validating these potential planetary signals. We highlight previously undetected transit-like signatures, including several that may represent small objects in the habitable zone of their host stars.

  5. Time-varying subspace dimensionality: Useful as a seismic signal detection method?

    NASA Astrophysics Data System (ADS)

    Rowe, C. A.; Stead, R. J.; Begnaud, M. L.

    2012-12-01

    We explore the application of dimensional analysis to the problem of anomaly detection in multichannel time series. These techniques, which have been used for real-time load management in large computer systems, revolve around the time-varying dimensionality estimates of the signal subspace. Our application is to multiple channels of incoming seismic waveform data, as from a large array or across a network. Subspace analysis has been applied to seismic data before, but the routine use of the method is for the identification of a particular signal type, and requires a priori information about the range of signals for which the algorithm is searching. In this paradigm, a known but variable source (such as a mining region or aftershock sequence) provides known waveforms that are assumed to span the space occupied by incoming events of interest. Singular value decomposition or principal components analysis of the identified waveforms will allow for the selection of basis vectors that define the subspace onto which incoming signals are projected, to determine whether they belong to the source population of interest. In our application we do not seek to compare incoming signals to previously identified waveforms, but instead we seek to detect anomalies from the background behavior across an array or network. The background seismic levels will describe a signal space whose dimension may change markedly when an earthquake or other signal of interest occurs. We explore a variety of means by which we can evaluate the time-varying dimensionality of the signal space, and we compare the detection performance to other standard event detection methods.

  6. Combing signals from spontaneous reports and electronic health records for detection of adverse drug reactions

    PubMed Central

    Harpaz, Rave; Vilar, Santiago; DuMouchel, William; Salmasian, Hojjat; Haerian, Krystl; Shah, Nigam H; Chase, Herbert S; Friedman, Carol

    2013-01-01

    Objective Data-mining algorithms that can produce accurate signals of potentially novel adverse drug reactions (ADRs) are a central component of pharmacovigilance. We propose a signal-detection strategy that combines the adverse event reporting system (AERS) of the Food and Drug Administration and electronic health records (EHRs) by requiring signaling in both sources. We claim that this approach leads to improved accuracy of signal detection when the goal is to produce a highly selective ranked set of candidate ADRs. Materials and methods Our investigation was based on over 4 million AERS reports and information extracted from 1.2 million EHR narratives. Well-established methodologies were used to generate signals from each source. The study focused on ADRs related to three high-profile serious adverse reactions. A reference standard of over 600 established and plausible ADRs was created and used to evaluate the proposed approach against a comparator. Results The combined signaling system achieved a statistically significant large improvement over AERS (baseline) in the precision of top ranked signals. The average improvement ranged from 31% to almost threefold for different evaluation categories. Using this system, we identified a new association between the agent, rasburicase, and the adverse event, acute pancreatitis, which was supported by clinical review. Conclusions The results provide promising initial evidence that combining AERS with EHRs via the framework of replicated signaling can improve the accuracy of signal detection for certain operating scenarios. The use of additional EHR data is required to further evaluate the capacity and limits of this system and to extend the generalizability of these results. PMID:23118093

  7. Neural Mechanisms for Acoustic Signal Detection under Strong Masking in an Insect.

    PubMed

    Kostarakos, Konstantinos; Römer, Heiner

    2015-07-22

    Communication is fundamental for our understanding of behavior. In the acoustic modality, natural scenes for communication in humans and animals are often very noisy, decreasing the chances for signal detection and discrimination. We investigated the mechanisms enabling selective hearing under natural noisy conditions for auditory receptors and interneurons of an insect. In the studied katydid Mecopoda elongata species-specific calling songs (chirps) are strongly masked by signals of another species, both communicating in sympatry. The spectral properties of the two signals are similar and differ only in a small frequency band at 2 kHz present in the chirping species. Receptors sharply tuned to 2 kHz are completely unaffected by the masking signal of the other species, whereas receptors tuned to higher audio and ultrasonic frequencies show complete masking. Intracellular recordings of identified interneurons revealed two mechanisms providing response selectivity to the chirp. (1) Response selectivity is when several identified interneurons exhibit remarkably selective responses to the chirps, even at signal-to-noise ratios of -21 dB, since they are sharply tuned to 2 kHz. Their dendritic arborizations indicate selective connectivity with low-frequency receptors tuned to 2 kHz. (2) Novelty detection is when a second group of interneurons is broadly tuned but, because of strong stimulus-specific adaptation to the masker spectrum and "novelty detection" to the 2 kHz band present only in the conspecific signal, these interneurons start to respond selectively to the chirp shortly after the onset of the continuous masker. Both mechanisms provide the sensory basis for hearing at unfavorable signal-to-noise ratios. Significance statement: Animal and human acoustic communication may suffer from the same "cocktail party problem," when communication happens in noisy social groups. We address solutions for this problem in a model system of two katydids, where one species

  8. The Influence of a Crosshair Visual Aid on Observer Detection of Simulated Fetal Heart Rate Signals.

    PubMed

    Kennedy, Rebecca A; Scerbo, Mark W; Anderson-Montoya, Brittany L; Belfore, Lee A; Abuhamad, Alfred Z; Davis, Stephen S

    2016-03-01

    Objective To determine whether a visual aid overlaid on fetal heart rate (FHR) tracings increases detection of critical signals relative to images with no visual aid. Study Design In an experimental study, 21 undergraduate students viewed 240 images of simulated FHR tracings twice, once with the visual aids and once without aids. Performance was examined for images containing three different types of FHR signals (early deceleration, late deceleration, and acceleration) and four different FHR signal-to-noise ratios corresponding to FHR variability types (absent, minimal, moderate, and marked) identified by the National Institute of Child Health and Human Development (2008). Performance was analyzed using repeated-measures analyses of variance. Results The presence of the visual aid significantly improved correct detections of signals overall and decreased false alarms for the marked variability condition. Conclusion The results of the study provide evidence that the presence of a visual aid was useful in helping novices identify FHR signals in simulated maternal-fetal heart rate images. Further, the visual aid was most useful for conditions in which the signal is most difficult to detect (when FHR variability is highest).

  9. The Influence of a Crosshair Visual Aid on Observer Detection of Simulated Fetal Heart Rate Signals.

    PubMed

    Kennedy, Rebecca A; Scerbo, Mark W; Anderson-Montoya, Brittany L; Belfore, Lee A; Abuhamad, Alfred Z; Davis, Stephen S

    2016-03-01

    Objective To determine whether a visual aid overlaid on fetal heart rate (FHR) tracings increases detection of critical signals relative to images with no visual aid. Study Design In an experimental study, 21 undergraduate students viewed 240 images of simulated FHR tracings twice, once with the visual aids and once without aids. Performance was examined for images containing three different types of FHR signals (early deceleration, late deceleration, and acceleration) and four different FHR signal-to-noise ratios corresponding to FHR variability types (absent, minimal, moderate, and marked) identified by the National Institute of Child Health and Human Development (2008). Performance was analyzed using repeated-measures analyses of variance. Results The presence of the visual aid significantly improved correct detections of signals overall and decreased false alarms for the marked variability condition. Conclusion The results of the study provide evidence that the presence of a visual aid was useful in helping novices identify FHR signals in simulated maternal-fetal heart rate images. Further, the visual aid was most useful for conditions in which the signal is most difficult to detect (when FHR variability is highest). PMID:26989564

  10. Stochastic Resonance in an Underdamped System with Pinning Potential for Weak Signal Detection

    PubMed Central

    Zhang, Haibin; He, Qingbo; Kong, Fanrang

    2015-01-01

    Stochastic resonance (SR) has been proved to be an effective approach for weak sensor signal detection. This study presents a new weak signal detection method based on a SR in an underdamped system, which consists of a pinning potential model. The model was firstly discovered from magnetic domain wall (DW) in ferromagnetic strips. We analyze the principle of the proposed underdamped pinning SR (UPSR) system, the detailed numerical simulation and system performance. We also propose the strategy of selecting the proper damping factor and other system parameters to match a weak signal, input noise and to generate the highest output signal-to-noise ratio (SNR). Finally, we have verified its effectiveness with both simulated and experimental input signals. Results indicate that the UPSR performs better in weak signal detection than the conventional SR (CSR) with merits of higher output SNR, better anti-noise and frequency response capability. Besides, the system can be designed accurately and efficiently owing to the sensibility of parameters and potential diversity. The features also weaken the limitation of small parameters on SR system. PMID:26343662

  11. Weak signal amplification and detection by higher-order sensory neurons.

    PubMed

    Jung, Sarah N; Longtin, Andre; Maler, Leonard

    2016-04-01

    Sensory systems must extract behaviorally relevant information and therefore often exhibit a very high sensitivity. How the nervous system reaches such high sensitivity levels is an outstanding question in neuroscience. Weakly electric fish (Apteronotus leptorhynchus/albifrons) are an excellent model system to address this question because detailed background knowledge is available regarding their behavioral performance and its underlying neuronal substrate. Apteronotus use their electrosense to detect prey objects. Therefore, they must be able to detect electrical signals as low as 1 μV while using a sensory integration time of <200 ms. How these very weak signals are extracted and amplified by the nervous system is not yet understood. We studied the responses of cells in the early sensory processing areas, namely, the electroreceptor afferents (EAs) and pyramidal cells (PCs) of the electrosensory lobe (ELL), the first-order electrosensory processing area. In agreement with previous work we found that EAs cannot encode very weak signals with a spike count code. However, PCs can encode prey mimic signals by their firing rate, revealing a huge signal amplification between EAs and PCs and also suggesting differences in their stimulus encoding properties. Using a simple leaky integrate-and-fire (LIF) model we predict that the target neurons of PCs in the midbrain torus semicircularis (TS) are able to detect very weak signals. In particular, TS neurons could do so by assuming biologically plausible convergence rates as well as very simple decoding strategies such as temporal integration, threshold crossing, and combining the inputs of PCs.

  12. Stochastic Resonance in an Underdamped System with Pinning Potential for Weak Signal Detection.

    PubMed

    Zhang, Haibin; He, Qingbo; Kong, Fanrang

    2015-08-28

    Stochastic resonance (SR) has been proved to be an effective approach for weak sensor signal detection. This study presents a new weak signal detection method based on a SR in an underdamped system, which consists of a pinning potential model. The model was firstly discovered from magnetic domain wall (DW) in ferromagnetic strips. We analyze the principle of the proposed underdamped pinning SR (UPSR) system, the detailed numerical simulation and system performance. We also propose the strategy of selecting the proper damping factor and other system parameters to match a weak signal, input noise and to generate the highest output signal-to-noise ratio (SNR). Finally, we have verified its effectiveness with both simulated and experimental input signals. Results indicate that the UPSR performs better in weak signal detection than the conventional SR (CSR) with merits of higher output SNR, better anti-noise and frequency response capability. Besides, the system can be designed accurately and efficiently owing to the sensibility of parameters and potential diversity. The features also weaken the limitation of small parameters on SR system.

  13. Wideband signal detection using a Nyquist folding analog-to-information receiver in multipath fading environment

    NASA Astrophysics Data System (ADS)

    Odejide, Olusegun; Annamalai, Annamalai; Akujuobi, Cajetan

    2010-04-01

    The need to efficiently and effectively monitor the frequency spectrum for identification of unoccupied bands is essential in communication systems such as Cognitive Radio (CR), battlefield communications, etc. The Nyquist Folding Analog-to-Information Receiver (NYFR) which is based on the theory of Compressed Sensing has been proposed recently to address this problem in a sparse environment. Although, typical CS techniques, involve random projections followed by a computationally intensive signal reconstruction process, the methods used in NYFR does not requires the laborious l1 minimization algorithm. The NYFR performs analog compression via a non-uniform sampling process that induces a chirp-like modulation on each received signal. Signal parameters can simply be determined by using timefrequency analysis techniques without full signal reconstruction. This paper revisits the detection problem of using NYFR for information recovery for appropriate frequency detection when the original signal in the presence of both the additive white Gaussian noise and Rice multipath fading. An automatic detection algorithm was also developed to determine the detected frequency parameters without looking at the FFT spectrogram plot.

  14. Detection of driving fatigue by using noncontact EMG and ECG signals measurement system.

    PubMed

    Fu, Rongrong; Wang, Hong

    2014-05-01

    Driver fatigue can be detected by constructing a discriminant mode using some features obtained from physiological signals. There exist two major challenges of this kind of methods. One is how to collect physiological signals from subjects while they are driving without any interruption. The other is to find features of physiological signals that are of corresponding change with the loss of attention caused by driver fatigue. Driving fatigue is detected based on the study of surface electromyography (EMG) and electrocardiograph (ECG) during the driving period. The noncontact data acquisition system was used to collect physiological signals from the biceps femoris of each subject to tackle the first challenge. Fast independent component analysis (FastICA) and digital filter were utilized to process the original signals. Based on the statistical analysis results given by Kolmogorov-Smirnov Z test, the peak factor of EMG (p < 0.001) and the maximum of the cross-relation curve of EMG and ECG (p < 0.001) were selected as the combined characteristic to detect fatigue of drivers. The discriminant criterion of fatigue was obtained from the training samples by using Mahalanobis distance, and then the average classification accuracy was given by 10-fold cross-validation. The results showed that the method proposed in this paper can give well performance in distinguishing the normal state and fatigue state. The noncontact, onboard vehicle drivers' fatigue detection system was developed to reduce fatigue-related risks.

  15. Analog CMOS design for optical coherence tomography signal detection and processing.

    PubMed

    Xu, Wei; Mathine, David L; Barton, Jennifer K

    2008-02-01

    A CMOS circuit was designed and fabricated for optical coherence tomography (OCT) signal detection and processing. The circuit includes a photoreceiver, differential gain stage and lock-in amplifier based demodulator. The photoreceiver consists of a CMOS photodetector and low noise differential transimpedance amplifier which converts the optical interference signal into a voltage. The differential gain stage further amplifies the signal. The in-phase and quadrature channels of the lock-in amplifier each include an analog mixer and switched-capacitor low-pass filter with an external mixer reference signal. The interferogram envelope and phase can be extracted with this configuration, enabling Doppler OCT measurements. A sensitivity of -80 dB is achieved with faithful reproduction of the interferometric signal envelope. A sample image of finger tip is presented. PMID:18269983

  16. Approximations to ideal-observer performance on signal-detection tasks.

    PubMed

    Clarkson, E; Barrett, H H

    2000-04-10

    The ideal-observer performance, as measured by the area under the receiver's operating characteristic curve, is computed for six examples of signal-detection tasks. Exact values for this quantity, as well as approximations based on the signal-to-noise ratio of the log likelihood and the likelihood-generating function, are found. The noise models considered are normal, exponential, Poisson, and two-sided exponential. The signal may affect the mean or the variance in each case. It is found that the approximation from the likelihood-generating function tracks well with the exact area, whereas the log-likelihood signal-to-noise approximation can fail badly. The signal-to-noise ratio of the likelihood ratio itself is also computed for each example to demonstrate that it is not a good measure of ideal-observer performance. PMID:18345075

  17. Development of an apnea detection algorithm based on temporal analysis of thoracic respiratory effort signal

    NASA Astrophysics Data System (ADS)

    Dell'Aquila, C. R.; Cañadas, G. E.; Correa, L. S.; Laciar, E.

    2016-04-01

    This work describes the design of an algorithm for detecting apnea episodes, based on analysis of thorax respiratory effort signal. Inspiration and expiration time, and range amplitude of respiratory cycle were evaluated. For range analysis the standard deviation statistical tool was used over respiratory signal temporal windows. The validity of its performance was carried out in 8 records of Apnea-ECG database that has annotations of apnea episodes. The results are: sensitivity (Se) 73%, specificity (Sp) 83%. These values can be improving eliminating artifact of signal records.

  18. A novel scheme to aid coherent detection of GMSK signals in fast Rayleigh fading channels

    NASA Technical Reports Server (NTRS)

    Leung, Patrick S. K.; Feher, Kamilo

    1990-01-01

    A novel scheme to insert carrier pilot to Gaussian Minimum Shift Keying (GMSK) signal using Binary Block Code (BBC) and a highpass filter in baseband is proposed. This allows the signal to be coherently demodulated even in a fast Rayleigh fading environment. As an illustrative example, the scheme is applied to a 16 kb/s GMSK signal, and its performance over a fast Rayleigh fading channel is investigated using computer simulation. This modem's 'irreducible error rate' is found to be Pe = 5.5 x 10(exp -5) which is more than that of differential detection. The modem's performance in Rician fading channel is currently under investigation.

  19. Signal Waveform Detection with Statistical Automaton for Internet and Web Service Streaming

    PubMed Central

    Liu, Yiming; Huang, Nai-Lun; Zeng, Fufu; Lin, Fang-Ying

    2014-01-01

    In recent years, many approaches have been suggested for Internet and web streaming detection. In this paper, we propose an approach to signal waveform detection for Internet and web streaming, with novel statistical automatons. The system records network connections over a period of time to form a signal waveform and compute suspicious characteristics of the waveform. Network streaming according to these selected waveform features by our newly designed Aho-Corasick (AC) automatons can be classified. We developed two versions, that is, basic AC and advanced AC-histogram waveform automata, and conducted comprehensive experimentation. The results confirm that our approach is feasible and suitable for deployment. PMID:25032231

  20. Signal and image processing for early detection of coronary artery diseases: A review

    NASA Astrophysics Data System (ADS)

    Mobssite, Youness; Samir, B. Belhaouari; Mohamad Hani, Ahmed Fadzil B.

    2012-09-01

    Today biomedical signals and image based detection are a basic step to diagnose heart diseases, in particular, coronary artery diseases. The goal of this work is to provide non-invasive early detection of Coronary Artery Diseases relying on analyzing images and ECG signals as a combined approach to extract features, further classify and quantify the severity of DCAD by using B-splines method. In an aim of creating a prototype of screening biomedical imaging for coronary arteries to help cardiologists to decide the kind of treatment needed to reduce or control the risk of heart attack.

  1. Method and means for detecting optically transmitted signals and establishing optical interference pattern between electrodes

    DOEpatents

    Kostenbauder, Adnah G.

    1988-01-01

    A photodetector for detecting signal pulses transmitted in an optical carrier signal relies on the generation of electron-hole pairs and the diffusion of the generated electrons and holes to the electrodes on the surface of the semiconductor detector body for generating photovoltaic pulses. The detector utilizes the interference of optical waves for generating an electron-hole grating within the semiconductor body, and, by establishing an electron-hole pair maximum at one electrode and a minimum at the other electrode, a detectable voltaic pulse is generated across the electrode.

  2. Method and means for detecting optically transmitted signals and establishing optical interference pattern between electrodes

    DOEpatents

    Kostenbauder, A.G.

    1988-06-28

    A photodetector for detecting signal pulses transmitted in an optical carrier signal relies on the generation of electron-hole pairs and the diffusion of the generated electrons and holes to the electrodes on the surface of the semiconductor detector body for generating photovoltaic pulses. The detector utilizes the interference of optical waves for generating an electron-hole grating within the semiconductor body, and, by establishing an electron-hole pair maximum at one electrode and a minimum at the other electrode, a detectable voltaic pulse is generated across the electrode. 4 figs.

  3. Signal waveform detection with statistical automaton for internet and web service streaming.

    PubMed

    Tseng, Kuo-Kun; Ji, Yuzhu; Liu, Yiming; Huang, Nai-Lun; Zeng, Fufu; Lin, Fang-Ying

    2014-01-01

    In recent years, many approaches have been suggested for Internet and web streaming detection. In this paper, we propose an approach to signal waveform detection for Internet and web streaming, with novel statistical automatons. The system records network connections over a period of time to form a signal waveform and compute suspicious characteristics of the waveform. Network streaming according to these selected waveform features by our newly designed Aho-Corasick (AC) automatons can be classified. We developed two versions, that is, basic AC and advanced AC-histogram waveform automata, and conducted comprehensive experimentation. The results confirm that our approach is feasible and suitable for deployment.

  4. Impaired binaural hearing in children produced by a threshold level of middle ear disease.

    PubMed

    Hogan, Sarah C M; Moore, David R

    2003-06-01

    Otitis media with effusion (OME), a form of middle ear disease, is the most common reason for young children both to visit their family doctor and to have surgery. Almost all children have at least a single episode of OME before their first birthday and annual incidence rates exceed 50% in each of the first five years. For most children, OME occurs infrequently, but about 10-15% of children have OME during more than half of their first six years. Middle ear effusions attenuate and delay sound, causing conductive sound distortion during the crucial years for language acquisition. The many studies of OME effects on language and other indices of development have produced mixed results. However, a consensus is emerging of mild language impairment in the preschool years, with subsequent performance, emotional, and behavioral difficulties. In addition to the peripheral hearing loss produced directly by the disease, binaural and other central auditory deficits can outlive the OME. It has been unclear which children are at risk of central impairment following OME, since the children studied have generally been recruited from otolaryngology clinics. Consequently, a detailed prospective history of the middle ear status of participants has not been available. By studying six-year-old children with a lifetime known history of OME, we show in this study that only those children with a cumulative OME experience of more than about half the time during the first five years consistently have residual impaired binaural hearing. PMID:12943367

  5. Representation of binaural spatial cues in field L of the barn owl forebrain.

    PubMed

    Cohen, Y E; Knudsen, E I

    1998-02-01

    This study examined the representation of spatial information in the barn owl Field L, the first telencephalic processing stage of the classical auditory pathway. Field L units were recorded extracellularly, and their responses to dichotically presented interaural time differences (ITD) and interaural level differences (ILD) were tested. We observed a variety of tuning profiles in Field L. Some sites were not sensitive to ITD or ILD. Other sites, especially those in the high-frequency region, were highly selective for values of ITD and ILD. These sites had multipeaked (commonly called "phase ambiguous") ITD tuning profiles and were tuned for a single value of ILD. The tuning properties of these sites are similar to those seen in the lateral shell of the central nucleus of the inferior colliculus. Although the tuning properties of Field L sites were similar to those observed in the inferior colliculus, the functional organization of this spatial information was fundamentally different. Whereas in the inferior colliculus spatial information is organized into global topographics maps, in Field L spatial information is organized into local clusters, with sites having similar binaural tuning properties grouped together. The representation of binaural cues in Field L suggests that it is involved in auditory space processing but at a lower level of information processing than the auditory archistriatum, a forebrain area that is specialized for processing spatial information, and that the levels of information processing in the forebrain space processing pathway are remarkably similar to those in the well-known midbrain space processing pathway. PMID:9463449

  6. Impaired binaural hearing in children produced by a threshold level of middle ear disease.

    PubMed

    Hogan, Sarah C M; Moore, David R

    2003-06-01

    Otitis media with effusion (OME), a form of middle ear disease, is the most common reason for young children both to visit their family doctor and to have surgery. Almost all children have at least a single episode of OME before their first birthday and annual incidence rates exceed 50% in each of the first five years. For most children, OME occurs infrequently, but about 10-15% of children have OME during more than half of their first six years. Middle ear effusions attenuate and delay sound, causing conductive sound distortion during the crucial years for language acquisition. The many studies of OME effects on language and other indices of development have produced mixed results. However, a consensus is emerging of mild language impairment in the preschool years, with subsequent performance, emotional, and behavioral difficulties. In addition to the peripheral hearing loss produced directly by the disease, binaural and other central auditory deficits can outlive the OME. It has been unclear which children are at risk of central impairment following OME, since the children studied have generally been recruited from otolaryngology clinics. Consequently, a detailed prospective history of the middle ear status of participants has not been available. By studying six-year-old children with a lifetime known history of OME, we show in this study that only those children with a cumulative OME experience of more than about half the time during the first five years consistently have residual impaired binaural hearing.

  7. Modeling binaural responses in the auditory brainstem to electric stimulation of the auditory nerve.

    PubMed

    Chung, Yoojin; Delgutte, Bertrand; Colburn, H Steven

    2015-02-01

    Bilateral cochlear implants (CIs) provide improvements in sound localization and speech perception in noise over unilateral CIs. However, the benefits arise mainly from the perception of interaural level differences, while bilateral CI listeners' sensitivity to interaural time difference (ITD) is poorer than normal. To help understand this limitation, a set of ITD-sensitive neural models was developed to study binaural responses to electric stimulation. Our working hypothesis was that central auditory processing is normal with bilateral CIs so that the abnormality in the response to electric stimulation at the level of the auditory nerve fibers (ANFs) is the source of the limited ITD sensitivity. A descriptive model of ANF response to both acoustic and electric stimulation was implemented and used to drive a simplified biophysical model of neurons in the medial superior olive (MSO). The model's ITD sensitivity was found to depend strongly on the specific configurations of membrane and synaptic parameters for different stimulation rates. Specifically, stronger excitatory synaptic inputs and faster membrane responses were required for the model neurons to be ITD-sensitive at high stimulation rates, whereas weaker excitatory synaptic input and slower membrane responses were necessary at low stimulation rates, for both electric and acoustic stimulation. This finding raises the possibility of frequency-dependent differences in neural mechanisms of binaural processing; limitations in ITD sensitivity with bilateral CIs may be due to a mismatch between stimulation rate and cell parameters in ITD-sensitive neurons. PMID:25348578

  8. Automated infrasound signal detection algorithms implemented in MatSeis - Infra Tool.

    SciTech Connect

    Hart, Darren

    2004-07-01

    MatSeis's infrasound analysis tool, Infra Tool, uses frequency slowness processing to deconstruct the array data into three outputs per processing step: correlation, azimuth and slowness. Until now, an experienced analyst trained to recognize a pattern observed in outputs from signal processing manually accomplished infrasound signal detection. Our goal was to automate the process of infrasound signal detection. The critical aspect of infrasound signal detection is to identify consecutive processing steps where the azimuth is constant (flat) while the time-lag correlation of the windowed waveform is above background value. These two statements describe the arrival of a correlated set of wavefronts at an array. The Hough Transform and Inverse Slope methods are used to determine the representative slope for a specified number of azimuth data points. The representative slope is then used in conjunction with associated correlation value and azimuth data variance to determine if and when an infrasound signal was detected. A format for an infrasound signal detection output file is also proposed. The detection output file will list the processed array element names, followed by detection characteristics for each method. Each detection is supplied with a listing of frequency slowness processing characteristics: human time (YYYY/MM/DD HH:MM:SS.SSS), epochal time, correlation, fstat, azimuth (deg) and trace velocity (km/s). As an example, a ground truth event was processed using the four-element DLIAR infrasound array located in New Mexico. The event is known as the Watusi chemical explosion, which occurred on 2002/09/28 at 21:25:17 with an explosive yield of 38,000 lb TNT equivalent. Knowing the source and array location, the array-to-event distance was computed to be approximately 890 km. This test determined the station-to-event azimuth (281.8 and 282.1 degrees) to within 1.6 and 1.4 degrees for the Inverse Slope and Hough Transform detection algorithms, respectively, and

  9. SEMICONDUCTOR TECHNOLOGY A signal processing method for the friction-based endpoint detection system of a CMP process

    NASA Astrophysics Data System (ADS)

    Chi, Xu; Dongming, Guo; Zhuji, Jin; Renke, Kang

    2010-12-01

    A signal processing method for the friction-based endpoint detection system of a chemical mechanical polishing (CMP) process is presented. The signal process method uses the wavelet threshold denoising method to reduce the noise contained in the measured original signal, extracts the Kalman filter innovation from the denoised signal as the feature signal, and judges the CMP endpoint based on the feature of the Kalman filter innovation sequence during the CMP process. Applying the signal processing method, the endpoint detection experiments of the Cu CMP process were carried out. The results show that the signal processing method can judge the endpoint of the Cu CMP process.

  10. Pipe wall damage detection by electromagnetic acoustic transducer generated guided waves in absence of defect signals.

    PubMed

    Vasiljevic, Milos; Kundu, Tribikram; Grill, Wolfgang; Twerdowski, Evgeny

    2008-05-01

    Most investigators emphasize the importance of detecting the reflected signal from the defect to determine if the pipe wall has any damage and to predict the damage location. However, often the small signal from the defect is hidden behind the other arriving wave modes and signal noise. To overcome the difficulties associated with the identification of the small defect signal in the time history plots, in this paper the time history is analyzed well after the arrival of the first defect signal, and after different wave modes have propagated multiple times through the pipe. It is shown that the defective pipe can be clearly identified by analyzing these late arriving diffuse ultrasonic signals. Multiple reflections and scattering of the propagating wave modes by the defect and pipe ends do not hamper the defect detection capability; on the contrary, it apparently stabilizes the signal and makes it easier to distinguish the defective pipe from the defect-free pipe. This paper also highlights difficulties associated with the interpretation of the recorded time histories due to mode conversion by the defect. The design of electro-magnetic acoustic transducers used to generate and receive the guided waves in the pipe is briefly described in the paper.

  11. Efficient detection and signal parameter estimation with application to high dynamic GPS receiver

    NASA Technical Reports Server (NTRS)

    Kumar, Rajendra (Inventor)

    1990-01-01

    In a system for deriving position, velocity, and acceleration information from a received signal emitted from an object to be tracked wherein the signal comprises a carrier signal phase modulated by unknown binary data and experiencing very high Doppler and Doppler rate, this invention provides combined estimation/detection apparatus for simultaneously detecting data bits and obtaining estimates of signal parameters such as carrier phase and frequency related to receiver dynamics in a sequential manner. There is a first stage for obtaining estimates of the signal parameters related to phase and frequency in the vicinity of possible data transitions on the basis of measurements obtained within a current data bit. A second stage uses the estimates from the first stage to decide whether or not a data transition has actually occurred. There is a third stage for removing data modulation from the received signal when a data transition has occurred and a fourth stage for using the received signal with data modulation removed therefrom to update global parameters which are dependent only upon receiver dynamics and independent of data modulation. Finally, there is a fifth stage for using the global parameters to determine the position, velocity, and acceleration of the object.

  12. Fission signal detection using helium-4 gas fast neutron scintillation detectors

    SciTech Connect

    Lewis, J. M. Kelley, R. P.; Jordan, K. A.; Murer, D.

    2014-07-07

    We demonstrate the unambiguous detection of the fission neutron signal produced in natural uranium during active neutron interrogation using a deuterium-deuterium fusion neutron generator and a high pressure {sup 4}He gas fast neutron scintillation detector. The energy deposition by individual neutrons is quantified, and energy discrimination is used to differentiate the induced fission neutrons from the mono-energetic interrogation neutrons. The detector can discriminate between different incident neutron energies using pulse height discrimination of the slow scintillation component of the elastic scattering interaction between a neutron and the {sup 4}He atom. Energy histograms resulting from this data show the buildup of a detected fission neutron signal at higher energies. The detector is shown here to detect a unique fission neutron signal from a natural uranium sample during active interrogation with a (d, d) neutron generator. This signal path has a direct application to the detection of shielded nuclear material in cargo and air containers. It allows for continuous interrogation and detection while greatly minimizing the potential for false alarms.

  13. Structure-based modeling of head-related transfer functions towards interactive customization of binaural sound systems

    NASA Astrophysics Data System (ADS)

    Gupta, Navarun

    2003-10-01

    One of the most popular techniques for creating spatialized virtual sounds is based on the use of Head-Related Transfer Functions (HRTFs). HRTFs are signal processing models that represent the modifications undergone by the acoustic signal as it travels from a sound source to each of the listener's eardrums. These modifications are due to the interaction of the acoustic waves with the listener's torso, shoulders, head and pinnae, or outer ears. As such, HRTFs are somewhat different for each listener. For a listener to perceive synthesized 3-D sound cues correctly, the synthesized cues must be similar to the listener's own HRTFs. One can measure individual HRTFs using specialized recording systems, however, these systems are prohibitively expensive and restrict the portability of the 3-D sound system. HRTF-based systems also face several computational challenges. This dissertation presents an alternative method for the synthesis of binaural spatialized sounds. The sound entering the pinna undergoes several reflective, diffractive and resonant phenomena, which determine the HRTF. Using signal processing tools, such as Prony's signal modeling method, an appropriate set of time delays and a resonant frequency were used to approximate the measured Head-Related Impulse Responses (HRIRs). Statistical analysis was used to find out empirical equations describing how the reflections and resonances are determined by the shape and size of the pinna features obtained from 3D images of 15 experimental subjects modeled in the project. These equations were used to yield "Model HRTFs" that can create elevation effects. Listening tests conducted on 10 subjects show that these model HRTFs are 5% more effective than generic HRTFs when it comes to localizing sounds in the frontal plane. The number of reversals (perception of sound source above the horizontal plane when actually it is below the plane and vice versa) was also reduced by 5.7%, showing the perceptual effectiveness of this

  14. Signal averaging limitations in heterodyne- and direct-detection laser remote sensing measurements

    NASA Technical Reports Server (NTRS)

    Menyuk, N.; Killinger, D. K.; Menyuk, C. R.

    1983-01-01

    The improvement in measurement uncertainty brought about by the averaging of increasing numbers of pulse return signals in both heterodyne- and direct-detection lidar systems is investigated. A theoretical analysis is presented which shows the standard deviation of the mean measurement to decrease as the inverse square root of the number of measurements, except in the presence of temporal correlation. Experimental measurements based on a dual-hybrid-TEA CO2 laser differential absorption lidar system are reported which demonstrate that the actual reduction in the standard deviation of the mean in both heterodyne- and direct-detection systems is much slower than the inverse square-root dependence predicted for uncorrelated signals, but is in agreement with predictions in the event of temporal correlation. Results thus favor the use of direct detection at relatively short range where the lower limit of the standard deviation of the mean is about 2 percent, but advantages of heterodyne detection at longer ranges are noted.

  15. Neural Mechanisms for Acoustic Signal Detection under Strong Masking in an Insect

    PubMed Central

    Römer, Heiner

    2015-01-01

    Communication is fundamental for our understanding of behavior. In the acoustic modality, natural scenes for communication in humans and animals are often very noisy, decreasing the chances for signal detection and discrimination. We investigated the mechanisms enabling selective hearing under natural noisy conditions for auditory receptors and interneurons of an insect. In the studied katydid Mecopoda elongata species-specific calling songs (chirps) are strongly masked by signals of another species, both communicating in sympatry. The spectral properties of the two signals are similar and differ only in a small frequency band at 2 kHz present in the chirping species. Receptors sharply tuned to 2 kHz are completely unaffected by the masking signal of the other species, whereas receptors tuned to higher audio and ultrasonic frequencies show complete masking. Intracellular recordings of identified interneurons revealed two mechanisms providing response selectivity to the chirp. (1) Response selectivity is when several identified interneurons exhibit remarkably selective responses to the chirps, even at signal-to-noise ratios of −21 dB, since they are sharply tuned to 2 kHz. Their dendritic arborizations indicate selective connectivity with low-frequency receptors tuned to 2 kHz. (2) Novelty detection is when a second group of interneurons is broadly tuned but, because of strong stimulus-specific adaptation to the masker spectrum and “novelty detection” to the 2 kHz band present only in the conspecific signal, these interneurons start to respond selectively to the chirp shortly after the onset of the continuous masker. Both mechanisms provide the sensory basis for hearing at unfavorable signal-to-noise ratios. SIGNIFICANCE STATEMENT Animal and human acoustic communication may suffer from the same “cocktail party problem,” when communication happens in noisy social groups. We address solutions for this problem in a model system of two katydids, where one

  16. Detection of delamination defects in CFRP materials using ultrasonic signal processing.

    PubMed

    Benammar, Abdessalem; Drai, Redouane; Guessoum, Abderrezak

    2008-12-01

    In this paper, signal processing techniques are tested for their ability to resolve echoes associated with delaminations in carbon fiber-reinforced polymer multi-layered composite materials (CFRP) detected by ultrasonic methods. These methods include split spectrum processing (SSP) and the expectation-maximization (EM) algorithm. A simulation study on defect detection was performed, and results were validated experimentally on CFRP with and without delamination defects taken from aircraft. Comparison of the methods for their ability to resolve echoes are made.

  17. Multi-Phenomenology Explosion Monitoring (Multi-PEM). Signal Detection. Research to target smaller sources for tomorrow’s missions

    SciTech Connect

    Carmichael, Joshua Daniel

    2015-12-12

    This a guide on how to detect and identify explosions from various sources. For example, nuclear explosions produce acoustic, optical, and EMP outputs. Each signal can be buried in noise, but fusing detection statistics from seismic, acoustic, and electromagnetic signals results in clear detection otherwise unobtainable.

  18. Basic elements of an international terrestrial reply following the detection of a signal from extraterrestrial intelligence

    NASA Astrophysics Data System (ADS)

    Reijnen, G. C. M.

    One of the most tantalizing questions human intelligence has posed itself since the beginnings of time is whether we are alone in the Universe. And if not, where are "the others," and is it possible that these "others" may contact us, with or without our knowledge? Scientific literature abounds with theories pro and con, and if any subject ever lent itself to make-believe it is this one. Connected with the scientific theories on the subject, which are so often misunderstood, popular belief has led to a steady stream of publications which have done nothing if they have not greatly hampered the real issue. In legal circles the subject of possible contacts with extraterrestrial intelligence was first discussed in the literature in the early 1960's when, among others, Andrew Haley wrote, in 1965, about "Space Law and Government." This publication appeared in the midst of the United Nations preparations for what was to become, in 1967, the Outer Space Treaty. Though the idea of an international protocol governing actions after the detection of a signal from extraterrestrial intelligence has never been on the agenda of the United Nations Committee on the Peaceful Uses of Outer Space, space lawyers continue to think and to write about that subject. Recent advances in spaceflight, in particular the Voyager missions to the outer planets of our solar system, give the subject a new impetus. The present paper is intended to dwell upon present scientific thoughts about the likelihood that a signal from extraterrestrial intelligence will be detected in the near future. Although this likelihood appears to be remote, it seems, nevertheless, worthwhile that discussion continues in space legal circles regarding the formulation of an international protocol for activities following the detection of a signal from extraterrestrial intelligence. Since the confirmed detection of a signal from extraterrestrial intelligence could well be of crucial importance for the continuing existence of

  19. Automated wavelet denoising of photoacoustic signals for circulating melanoma cell detection and burn image reconstruction.

    PubMed

    Holan, Scott H; Viator, John A

    2008-06-21

    Photoacoustic image reconstruction may involve hundreds of point measurements, each of which contributes unique information about the subsurface absorbing structures under study. For backprojection imaging, two or more point measurements of photoacoustic waves induced by irradiating a biological sample with laser light are used to produce an image of the acoustic source. Each of these measurements must undergo some signal processing, such as denoising or system deconvolution. In order to process the numerous signals, we have developed an automated wavelet algorithm for denoising signals. We appeal to the discrete wavelet transform for denoising photoacoustic signals generated in a dilute melanoma cell suspension and in thermally coagulated blood. We used 5, 9, 45 and 270 melanoma cells in the laser beam path as test concentrations. For the burn phantom, we used coagulated blood in 1.6 mm silicon tube submerged in Intralipid. Although these two targets were chosen as typical applications for photoacoustic detection and imaging, they are of independent interest. The denoising employs level-independent universal thresholding. In order to accommodate nonradix-2 signals, we considered a maximal overlap discrete wavelet transform (MODWT). For the lower melanoma cell concentrations, as the signal-to-noise ratio approached 1, denoising allowed better peak finding. For coagulated blood, the signals were denoised to yield a clean photoacoustic resulting in an improvement of 22% in the reconstructed image. The entire signal processing technique was automated so that minimal user intervention was needed to reconstruct the images. Such an algorithm may be used for image reconstruction and signal extraction for applications such as burn depth imaging, depth profiling of vascular lesions in skin and the detection of single cancer cells in blood samples. PMID:18495977

  20. NOTE: Automated wavelet denoising of photoacoustic signals for circulating melanoma cell detection and burn image reconstruction

    NASA Astrophysics Data System (ADS)

    Holan, Scott H.; Viator, John A.

    2008-06-01

    Photoacoustic image reconstruction may involve hundreds of point measurements, each of which contributes unique information about the subsurface absorbing structures under study. For backprojection imaging, two or more point measurements of photoacoustic waves induced by irradiating a biological sample with laser light are used to produce an image of the acoustic source. Each of these measurements must undergo some signal processing, such as denoising or system deconvolution. In order to process the numerous signals, we have developed an automated wavelet algorithm for denoising signals. We appeal to the discrete wavelet transform for denoising photoacoustic signals generated in a dilute melanoma cell suspension and in thermally coagulated blood. We used 5, 9, 45 and 270 melanoma cells in the laser beam path as test concentrations. For the burn phantom, we used coagulated blood in 1.6 mm silicon tube submerged in Intralipid. Although these two targets were chosen as typical applications for photoacoustic detection and imaging, they are of independent interest. The denoising employs level-independent universal thresholding. In order to accommodate nonradix-2 signals, we considered a maximal overlap discrete wavelet transform (MODWT). For the lower melanoma cell concentrations, as the signal-to-noise ratio approached 1, denoising allowed better peak finding. For coagulated blood, the signals were denoised to yield a clean photoacoustic resulting in an improvement of 22% in the reconstructed image. The entire signal processing technique was automated so that minimal user intervention was needed to reconstruct the images. Such an algorithm may be used for image reconstruction and signal extraction for applications such as burn depth imaging, depth profiling of vascular lesions in skin and the detection of single cancer cells in blood samples.

  1. Classification of change detection and change blindness from near-infrared spectroscopy signals.

    PubMed

    Tanaka, Hirokazu; Katura, Takusige

    2011-08-01

    Using a machine-learning classification algorithm applied to near-infrared spectroscopy (NIRS) signals, we classify a success (change detection) or a failure (change blindness) in detecting visual changes for a change-detection task. Five subjects perform a change-detection task, and their brain activities are continuously monitored. A support-vector-machine algorithm is applied to classify the change-detection and change-blindness trials, and correct classification probability of 70-90% is obtained for four subjects. Two types of temporal shapes in classification probabilities are found: one exhibiting a maximum value after the task is completed (postdictive type), and another exhibiting a maximum value during the task (predictive type). As for the postdictive type, the classification probability begins to increase immediately after the task completion and reaches its maximum in about the time scale of neuronal hemodynamic response, reflecting a subjective report of change detection. As for the predictive type, the classification probability shows an increase at the task initiation and is maximal while subjects are performing the task, predicting the task performance in detecting a change. We conclude that decoding change detection and change blindness from NIRS signal is possible and argue some future applications toward brain-machine interfaces.

  2. Classification of change detection and change blindness from near-infrared spectroscopy signals

    NASA Astrophysics Data System (ADS)

    Tanaka, Hirokazu; Katura, Takusige

    2011-08-01

    Using a machine-learning classification algorithm applied to near-infrared spectroscopy (NIRS) signals, we classify a success (change detection) or a failure (change blindness) in detecting visual changes for a change-detection task. Five subjects perform a change-detection task, and their brain activities are continuously monitored. A support-vector-machine algorithm is applied to classify the change-detection and change-blindness trials, and correct classification probability of 70-90% is obtained for four subjects. Two types of temporal shapes in classification probabilities are found: one exhibiting a maximum value after the task is completed (postdictive type), and another exhibiting a maximum value during the task (predictive type). As for the postdictive type, the classification probability begins to increase immediately after the task completion and reaches its maximum in about the time scale of neuronal hemodynamic response, reflecting a subjective report of change detection. As for the predictive type, the classification probability shows an increase at the task initiation and is maximal while subjects are performing the task, predicting the task performance in detecting a change. We conclude that decoding change detection and change blindness from NIRS signal is possible and argue some future applications toward brain-machine interfaces.

  3. Gold nanoparticle supported phospholipid membranes as a biomimetic biosensor platform for phosphoinositide signaling detection.

    PubMed

    Wen, Qian; Liu, Si-Jia; Tang, Li-Juan; Tang, Ying; Jiang, Jian-Hui

    2014-12-15

    Enzyme mediated phosphoinositide signaling plays important regulatory roles in diverse cellular processes and has close implication in human diseases. However, detection of phosphoinositide enzymes remains a challenge because of the difficulty in discriminating the phosphorylation patterns of phosphoinositide. Here we develop a novel enzyme-activated gold nanoparticles (AuNPs) assembly strategy as a homogeneous colorimetric biosensor for activity detection of phosphoinositide kinases and phosphatases. This strategy utilizes a biomimetic mechanism of phosphoinositide signaling, in which AuNP supported phospholipid membranes are constructed to mimic the cellular membrane substrate, and AuNPs modified with the pleckstrin homology (PH) domain of cytosolic proteins are designed for specific, multivalent recognition of phosphorylated phosphoinositides. This biomimetic strategy enables efficient enzymatic reactions of the substrate and highly selective detection of target enzyme. The biosensor is demonstrated for the detection of phosphoinositide 3-kinase (PI3K) and phosphatase with tensin homology (PTEN). The results revealed that it allows sensitive, rapid visual detection of the enzymes with pM detection limits and four-decade wide dynamic ranges, and is capable of detecting enzyme activities in complex cell lysate samples. This biosensor might provide a general biosensor platform for high-throughput detection of phosphoinositide enzymes with high sensitivity and selectivity in biomedical research and clinical diagnostics.

  4. Spatial uncertainty explains exogenous and endogenous attentional cuing effects in visual signal detection.

    PubMed

    Gould, Ian C; Wolfgang, Bradley J; Smith, Philip L

    2007-10-15

    Attentional cues may increase the detectability of a stimulus by increasing its signal-to-noise ratio (signal enhancement) or by increasing the efficiency of the observer's decision making by reducing uncertainty about the location of the stimulus (uncertainty reduction). Although signal enhancement has typically been found in detection tasks only when stimuli are backwardly masked, some recent studies have reported signal enhancement with unmasked stimuli under conditions of spatial uncertainty (E. L. Cameron, J. C. Tai, & M. Carrasco, 2002; M. Carrasco, C. Penpeci-Talgar, & M. Eckstein, 2000). To test whether these increases in sensitivity in unmasked displays were due to signal enhancement or uncertainty reduction, observers judged the orientation of unmasked Gabor patch stimuli in the presence or absence of fiducial markers that indicated their position in the display. Consistent with an uncertainty reduction hypothesis, cues produced large increases in sensitivity when stimuli were not localized perceptually but produced little or no systematic increase when they were localized by fiducial markers. The same general pattern of results was obtained with cues designed to engage the exogenous and endogenous orienting systems. The data suggest that, in practiced observers, the cuing effect for detecting unmasked stimuli is mainly due to uncertainty reduction.

  5. Short-term synaptic plasticity can enhance weak signal detectability in nonrenewal spike trains.

    PubMed

    Lüdtke, Niklas; Nelson, Mark E

    2006-12-01

    We study the encoding of weak signals in spike trains with interspike interval (ISI) correlations and the signals' subsequent detection in sensory neurons. Motivated by the observation of negative ISI correlations in auditory and electrosensory afferents, we assess the theoretical performance limits of an individual detector neuron receiving a weak signal distributed across multiple afferent inputs. We assess the functional role of ISI correlations in the detection process using statistical detection theory and derive two sequential likelihood ratio detector models: one for afferents with renewal statistics; the other for afferents with negatively correlated ISIs. We suggest a mechanism that might enable sensory neurons to implicitly compute conditional probabilities of presynaptic spikes by means of short-term synaptic plasticity. We demonstrate how this mechanism can enhance a postsynaptic neuron's sensitivity to weak signals by exploiting the correlation structure of the input spike trains. Our model not only captures fundamental aspects of early electrosensory signal processing in weakly electric fish, but may also bear relevance to the mammalian auditory system and other sensory modalities.

  6. [A De-Noising Algorithm for Fluorescence Detection Signal of Mineral Oil in Water by SWT].

    PubMed

    Wang, Yu-tian; Cheng, Peng-fei; Hou, Pei-guo; Yang, Zhe

    2015-05-01

    Fluorescence analysis is an important means of detecting mineral oil in water pollutants because of high sensitivity, selectivity, ease of design, etc. Noise generated from Photo detector will affect the sensitivity of fluorescence detection system, so the elimination of fluorescence signal noise has been a hot issue. For the fluorescence signal, due to the length increase of the branch set, it produces some boundary issues. The dbN wavelet family can flexibly balance the border issues, retain the useful signals and get. rid of noise, the de-noising effects of dbN families are compared, the db7 wavelet is chosen as the optimal wavelet. The noisy fluorescence signal is statically decomposed into 5 levels via db7 wavelet, and the thresholds are chosen adaptively based on the wavelet entropy theory. The pure fluorescence signal is obtained after the approximation coefficients and detail coefficients quantified by thresholds reconstructed. Compared with the DWT, the signal de-noised via SWT has the advantage of information integrity and time translation invariance.

  7. Sensitive detection of Escherichia coli O157:H7 based on cascade signal amplification in ELISA.

    PubMed

    Shan, Shan; Liu, Daofeng; Guo, Qi; Wu, Songsong; Chen, Rui; Luo, Kai; Hu, Liming; Xiong, Yonghua; Lai, Weihua

    2016-09-01

    In this study, cascade signal amplification in ELISA involving double-antibody sandwich ELISA and indirectly competitive ELISA was established to sensitively detect Escherichia coli O157:H7. In the double-antibody sandwich ELISA, a complex was formed comprising anti-E. coli O157:H7 polyclonal antibody, E. coli O157:H7, biotinylated anti-E. coli O157:H7 monoclonal antibody, streptavidin, and biotinylated β-lactamase. Penicillin solution was then added into the ELISA well and hydrolyzed by β-lactamase. Afterward, the penicillin solution was transferred to indirectly competitive ELISA. The concentration of penicillin can be sensitively detected in indirectly competitive ELISA. In the cascade signal amplification system, increasing the amount of added E. coli O157:H7 resulted in more β-lactamase and less penicillin. The detection sensitivity of E. coli O157:H7, which was 20cfu/mL with the cascade signal amplification in ELISA, was 1,000-fold higher than that of traditional ELISA. Furthermore, the novel method can be used to detect E. coli O157:H7 in milk (2cfu/g). Therefore, this new signaling strategy will facilitate analyses of highly sensitive foodborne pathogens.

  8. Mechanical design parameters for detection of nuclear signals by magnetic resonance force microscopy

    SciTech Connect

    Moore, G.J.; Hanlon, J.A.; Lamartine, B.; Hawley, M.; Solem, J.C.; Signer, S.; Jarmer, J.J.; Penttila, S.; Sillerud, L.O.; Pryputniewicz, R.J.

    1993-10-01

    Recent theoretical work has shown that mechanical detection of magnetic resonance from a single nuclear spin is in principle possible. This theory has recently been experimentally validated by the mechanical detection of electron spin resonance signals using microscale cantilevers. Currently we are extending this technology in an attempt to detect nuclear signals which are extending this technology in an attempt to detect nuclear signals which are three orders of magnitude lower in intensity than electron signals. In order to achieve the needed thousand-fold improvement in sensitivity we have undertaken the development of optimized mechanical cantilevers and highly polarized samples. Finite element modeling is used as a tool to simulate cantilever beam dynamics and to optimize the mechanical properties including Q, resonant frequency, amplitude of vibration and spring constant. Simulations are compared to experiments using heterodyne hologram interferometry. Nanofabrication of optimized cantilevers via ion milling will be directed by the outcome of these simulations and experiments. Highly polarized samples are developed using a three-fold approach: (1) high magnetic field strength (2.5T), (2) low temperature (1K), and (3) use of samples polarized by dynamic nuclear polarization. Our recent experiments have demonstrated nuclear polarizations in excess of 50% in molecules of toulene.

  9. Stimulus Disparity and Punisher Control of Human Signal-Detection Performance

    ERIC Educational Resources Information Center

    Lie, Celia; Alsop, Brent

    2010-01-01

    The present experiment examined the effects of varying stimulus disparity and relative punisher frequencies on signal detection by humans. Participants were placed into one of two groups. Group 3 participants were presented with 1:3 and 3:1 punisher frequency ratios, while Group 11 participants were presented with 1:11 and 11:1 punisher frequency…

  10. Rapid Acquisition of Bias in Signal Detection: Dynamics of Effective Reinforcement Allocation

    ERIC Educational Resources Information Center

    Hutsell, Blake; Jacobs, Eric A.

    2012-01-01

    We investigated changes in bias (preference for one response alternative) in signal detection when relative reinforcer frequency for correct responses varied across sessions. In Experiment 1, 4 rats responded in a two-stimulus, two-response identification procedure employing temporal stimuli (short vs. long houselight presentations). Relative…

  11. No Special K! A Signal Detection Framework for the Strategic Regulation of Memory Accuracy

    ERIC Educational Resources Information Center

    Higham, Philip A.

    2007-01-01

    Two experiments investigated criterion setting and metacognitive processes underlying the strategic regulation of accuracy on the Scholastic Aptitude Test (SAT) using Type-2 signal detection theory (SDT). In Experiment 1, report bias was manipulated by penalizing participants either 0.25 (low incentive) or 4 (high incentive) points for each error.…

  12. Investigating Aspects of the Language Learner's Confidence: An Application of the Theory of Signal Detection.

    ERIC Educational Resources Information Center

    Yule, George; And Others

    1985-01-01

    Describes a study of the role of confidence in the performance of English as a second language learners on a listening test. Some analytic procedures from the Theory of Signal Detection were applied. Results show the possibility of substantial differences in individual performance in terms of self-monitoring ability and confidence. (Author/SED)

  13. Applying Signal-Detection Theory to the Study of Observer Accuracy and Bias in Behavioral Assessment

    ERIC Educational Resources Information Center

    Lerman, Dorothea C.; Tetreault, Allison; Hovanetz, Alyson; Bellaci, Emily; Miller, Jonathan; Karp, Hilary; Mahmood, Angela; Strobel, Maggie; Mullen, Shelley; Keyl, Alice; Toupard, Alexis

    2010-01-01

    We evaluated the feasibility and utility of a laboratory model for examining observer accuracy within the framework of signal-detection theory (SDT). Sixty-one individuals collected data on aggression while viewing videotaped segments of simulated teacher-child interactions. The purpose of Experiment 1 was to determine if brief feedback and…

  14. A Signal-Detection Analysis of Sex Differences in the Perception of Emotional Faces

    ERIC Educational Resources Information Center

    Grimshaw, Gina M.; Bulman-Fleming, M. Barbara; Ngo, Cam

    2004-01-01

    A signal-detection task was used to assess sex differences in emotional face recognition under conditions of uncertainty. Computer images of Ekman faces showing sad, angry, happy, and fearful emotional states were presented for 50ms to thirty-six men and thirty-seven women. All participants monitored for presentation of either happy, angry, or sad…

  15. Effects of Point-Loss Punishers on Human Signal-Detection Performance

    ERIC Educational Resources Information Center

    Lie, Celia; Alsop, Brent

    2009-01-01

    Three experiments using human participants varied the distribution of point-gain reinforcers or point-loss punishers in two-alternative signal-detection procedures. Experiment 1 varied the distribution of point-gain reinforcers for correct responses (Group A) and point-loss punishers for errors (Group B) across conditions. Response bias varied…

  16. Right Hemisphere Sensitivity to Novel Metaphoric Relations: Application of the Signal Detection Theory

    ERIC Educational Resources Information Center

    Mashal, N.; Faust, M.

    2008-01-01

    The present study used the signal detection theory to test the hypothesis that the right hemisphere (RH) is more sensitive than the left hemisphere (LH) to the distant semantic relations in novel metaphoric expressions. In two divided visual field experiments, sensitivity (d') and criterion ([beta]) were calculated for responses to different types…

  17. A common signal detection model accounts for both perception and discrimination of the watercolor effect.

    PubMed

    Devinck, Frédéric; Knoblauch, Kenneth

    2012-03-21

    Establishing the relation between perception and discrimination is a fundamental objective in psychophysics, with the goal of characterizing the neural mechanisms mediating perception. Here, we show that a procedure for estimating a perceptual scale based on a signal detection model also predicts discrimination performance. We use a recently developed procedure, Maximum Likelihood Difference Scaling (MLDS), to measure the perceptual strength of a long-range, color, filling-in phenomenon, the Watercolor Effect (WCE), as a function of the luminance ratio between the two components of its generating contour. MLDS is based on an equal-variance, gaussian, signal detection model and yields a perceptual scale with interval properties. The strength of the fill-in percept increased 10-15 times the estimate of the internal noise level for a 3-fold increase in the luminance ratio. Each observer's estimated scale predicted discrimination performance in a subsequent paired-comparison task. A common signal detection model accounts for both the appearance and discrimination data. Since signal detection theory provides a common metric for relating discrimination performance and neural response, the results have implications for comparing perceptual and neural response functions.

  18. Conceptualization of the Complex Outcomes of Sexual Abuse: A Signal Detection Analysis

    ERIC Educational Resources Information Center

    Pechtel, Pia; Evans, Ian M.; Podd, John V.

    2011-01-01

    Eighty-five New Zealand based practitioners experienced in treating adults with a history of child sexual abuse participated in an online judgment study of child sexual abuse outcomes using signal detection theory methodology. Participants' level of sensitivity was assessed independent of their degree of response bias when discriminating (a) known…

  19. Signal amplification of streptavidin-horseradish peroxidase functionalized carbon nanotubes for amperometric detection of attomolar DNA.

    PubMed

    Gao, Wenchao; Dong, Haifeng; Lei, Jianping; Ji, Hanxu; Ju, Huangxian

    2011-05-14

    A novel biosensing strategy for selective electrochemical detection of DNA down to the attomolar level with a linear range of 5 orders of magnitude was developed by the specific recognitions of target DNA and streptavidin to biotin labelled molecular beacon and signal amplification of streptavidin-horseradish peroxidase functionalized carbon nanotubes.

  20. Using Signal Detection Theory to Model Changes in Serial Learning of Radiological Image Interpretation

    ERIC Educational Resources Information Center

    Boutis, Kathy; Pecaric, Martin; Seeto, Brian; Pusic, Martin

    2010-01-01

    Signal detection theory (SDT) parameters can describe a learner's ability to discriminate (d[prime symbol]) normal from abnormal and the learner's criterion ([lambda]) to under or overcall abnormalities. To examine the serial changes in SDT parameters with serial exposure to radiological cases. 46 participants were recruited for this study: 20…

  1. Signal Detection Analysis of Factors Associated with Diabetes among Semirural Mexican American Adults

    ERIC Educational Resources Information Center

    Hanni, K. D.; Ahn, D. A.; Winkleby, M. A.

    2013-01-01

    Signal detection analysis was used to evaluate a combination of sociodemographic, acculturation, mental health, health care, and chronic disease risk factors potentially associated with diabetes in a sample of 4,505 semirural Mexican American adults. Overall, 8.9% of adults had been diagnosed with diabetes. The analysis resulted in 12 mutually…

  2. Sensitive detection of Escherichia coli O157:H7 based on cascade signal amplification in ELISA.

    PubMed

    Shan, Shan; Liu, Daofeng; Guo, Qi; Wu, Songsong; Chen, Rui; Luo, Kai; Hu, Liming; Xiong, Yonghua; Lai, Weihua

    2016-09-01

    In this study, cascade signal amplification in ELISA involving double-antibody sandwich ELISA and indirectly competitive ELISA was established to sensitively detect Escherichia coli O157:H7. In the double-antibody sandwich ELISA, a complex was formed comprising anti-E. coli O157:H7 polyclonal antibody, E. coli O157:H7, biotinylated anti-E. coli O157:H7 monoclonal antibody, streptavidin, and biotinylated β-lactamase. Penicillin solution was then added into the ELISA well and hydrolyzed by β-lactamase. Afterward, the penicillin solution was transferred to indirectly competitive ELISA. The concentration of penicillin can be sensitively detected in indirectly competitive ELISA. In the cascade signal amplification system, increasing the amount of added E. coli O157:H7 resulted in more β-lactamase and less penicillin. The detection sensitivity of E. coli O157:H7, which was 20cfu/mL with the cascade signal amplification in ELISA, was 1,000-fold higher than that of traditional ELISA. Furthermore, the novel method can be used to detect E. coli O157:H7 in milk (2cfu/g). Therefore, this new signaling strategy will facilitate analyses of highly sensitive foodborne pathogens. PMID:27394946

  3. On the Measurement of Criterion Noise in Signal Detection Theory: The Case of Recognition Memory

    ERIC Educational Resources Information Center

    Kellen, David; Klauer, Karl Christoph; Singmann, Henrik

    2012-01-01

    Traditional approaches within the framework of signal detection theory (SDT; Green & Swets, 1966), especially in the field of recognition memory, assume that the positioning of response criteria is not a noisy process. Recent work (Benjamin, Diaz, & Wee, 2009; Mueller & Weidemann, 2008) has challenged this assumption, arguing not only…

  4. Two-Stage Dynamic Signal Detection: A Theory of Choice, Decision Time, and Confidence

    ERIC Educational Resources Information Center

    Pleskac, Timothy J.; Busemeyer, Jerome R.

    2010-01-01

    The 3 most often-used performance measures in the cognitive and decision sciences are choice, response or decision time, and confidence. We develop a random walk/diffusion theory--2-stage dynamic signal detection (2DSD) theory--that accounts for all 3 measures using a common underlying process. The model uses a drift diffusion process to account…

  5. Analysis of VLF signals associated to AGILE Terrestrial Gamma-ray Flashes detected over Central America

    NASA Astrophysics Data System (ADS)

    Marisaldi, Martino; Lyu, Fanchao; Cummer, Steven; Ursi, Alessandro

    2016-04-01

    Analysis of radio signals detected on ground and associated to Terrestrial Gamma-ray Flashes (TGFs) have proven to be a successful tool to extract information on the TGF itself and the possible associated lightning process. Triangulation of Very Low Frequency (VLF) signals by means of the Time Of Arrival technique provides TGF location with few km accuracy. The AGILE satellite is routinely observing TGFs on a narrow band across the Equator, limited by the small satellite orbital inclination (2.5°). However, until recently it was not possible to provide firm associations between AGILE TGFs and radio signals, because of two main limiting factors. First, dead-time effects led to a bias towards long duration events in AGILE TGF sample, which are less likely associated to strong radio pulses. In addition, most VLF detection networks are less sensitive along the equatorial region. Since the end of March 2015 a major change in the AGILE MiniCalorimeter instrument configuration resulted in a ten fold increase in TGF detection rate, and in the detection of events as short as 20 microseconds. 14% of the events in the new sample resulted simultaneous (within 200 microseconds) to sferics detected by the World Wide Lightning Location Network (WWLLN), therefore a source localisation is available for these events. We present here the first analysis of VLF waveforms associated to AGILE TGFs observed above Central America, detected by magnetic field sensors deployed in Puerto Rico. Among the seven TGFs with a WWLLN location at a distance lower than 10000 km from the sensors, four of them have detectable signals. These events are the closest to the sensors, with distance less than 7500 km. We present here the properties of these TGFs and the characteristics of the associated radio waveforms.

  6. Predicting the capture rate in the Sun from a direct detection signal independently of the astrophysics

    NASA Astrophysics Data System (ADS)

    Herrero-Garcia, Juan

    2016-05-01

    The goal of the works on which this talk is based is to relate a direct detection signal with neutrino limits from the Sun independently of the astrophysics. In order to achieve this we derive a halo-independent lower bound on the dark matter capture rate in the Sun from a direct detection signal, with which one can set upper limits on the branching ratios into different channels from the absence of a high-energy neutrino flux in neutrino observatories. We also extend this bound to the case of inelastic scattering, both endothermic and exothermic. From two inelastic signals we show how the dark matter mass, the mass difference of the states and the couplings to neutrons and protons can be obtained. Furthermore, one can also pin down the exothermic/endothermic nature of the scattering, and therefore a precise lower bound on the solar capture rate is predicted. We also discuss isospin violation and uncertainties due to form factors.

  7. Implication of Two-Coupled Differential Van der Pol Duffing Oscillator in Weak Signal Detection

    NASA Astrophysics Data System (ADS)

    Peng, Hang-hang; Xu, Xue-mei; Yang, Bing-chu; Yin, Lin-zi

    2016-04-01

    The principle of the Van der Pol Duffing oscillator for state transition and for determining critical value is described, which has been studied to indicate that the application of the Van der Pol Duffing oscillator in weak signal detection is feasible. On the basis of this principle, an improved two-coupled differential Van der Pol Duffing oscillator is proposed which can identify signals under any frequency and ameliorate signal-to-noise ratio (SNR). The analytical methods of the proposed model and the construction of the proposed oscillator are introduced in detail. Numerical experiments on the properties of the proposed oscillator compared with those of the Van der Pol Duffing oscillator are carried out. Our numerical simulations have confirmed the analytical treatment. The results demonstrate that this novel oscillator has better detection performance than the Van der Pol Duffing oscillator.

  8. UV-B detected by the UVR8 photoreceptor antagonizes auxin signaling and plant shade avoidance.

    PubMed

    Hayes, Scott; Velanis, Christos N; Jenkins, Gareth I; Franklin, Keara A

    2014-08-12

    Plants detect different facets of their radiation environment via specific photoreceptors to modulate growth and development. UV-B is perceived by the photoreceptor UV RESISTANCE LOCUS 8 (UVR8). The molecular mechanisms linking UVR8 activation to plant growth are not fully understood, however. When grown in close proximity to neighboring vegetation, shade-intolerant plants initiate dramatic stem elongation to overtop competitors. Here we show that UV-B, detected by UVR8, provides an unambiguous sunlight signal that inhibits shade avoidance responses in Arabidopsis thaliana by antagonizing the phytohormones auxin and gibberellin. UV-B triggers degradation of the transcription factors PHYTOCHROME INTERACTING FACTOR 4 and PHYTOCHROME INTERACTING FACTOR 5 and stabilizes growth-repressing DELLA proteins, inhibiting auxin biosynthesis via a dual mechanism. Our findings show that UVR8 signaling is closely integrated with other photoreceptor pathways to regulate auxin signaling and plant growth in sunlight.

  9. Damage detection in composite materials using optical fibers: recent advances in signal processing

    NASA Astrophysics Data System (ADS)

    Staszewski, Wieslaw J.; Read, Ian J.; Foote, Peter D.

    2000-06-01

    This paper is concerned with the passive impact detection system based on fiber Bragg grating sensors which can be either embedded or surface mounted on a composite structure. The focus of the paper is the methodology of the intelligent signal processing for the optical fiber sensor data. This methodology is briefly discussed and illustrated using simple examples which utilize the experimental data. The experimental study involves a series of simple impact tests. The composite panel is installed in a loading fame. An instrumented impactor is used to damage the panel at different positions with different energy levels. For each impact the data from optical fiber sensors is digitized, logged and used for signal processing. The paper shows the importance of the intelligent signal processing for impact damage detection based on optical fiber sensors.

  10. An intelligent procedure for watermelon ripeness detection based on vibration signals.

    PubMed

    Abbaszadeh, Rouzbeh; Moosavian, Ashkan; Rajabipour, Ali; Najafi, Gholamhassan

    2015-02-01

    In this paper, an efficient procedure for ripeness detection of watermelon was presented. A nondestructive method was used based on vibration response to determine the internal quality of watermelon. The responses of samples to vibration excitation were optically recorded by a Laser Doppler (LD) vibrometer. Vibration data was collected from watermelons of two qualities, namely, ripe and unripe. Vibration signals were transformed from time-domain to frequency-domain by fast Fourier transform (FFT). Twenty nine features were extracted from the FFT amplitude and phase angle of the vibration signals. K-nearest neighbor (KNN) analysis was applied as a classifier in decision-making stage. The experimental results showed that the usage of the FFT amplitude of the vibration signals gave the maximum classification accuracy. This method allowed identification at a 95.0 % level of efficiency. Hence, the proposed method can reliably detect watermelon ripeness.

  11. Seismic signal and noise assessment for footstep detection range estimation in different environments

    NASA Astrophysics Data System (ADS)

    Pakhomov, Alex; Goldburt, Tim

    2004-09-01

    The development of security systems based on seismic footstep detection is critical for homeland security and defense applications. The performance of these systems depends on various factors, including noise and signal levels in the real environment. This paper describes the effect of different real seismic noise sources -- such as highways, railroads, operating machinery, trees and shrubs swaying in the wind -- on seismic security system performance as these sources can be located close to the detection area. It is demonstrated that by moving away from these sources, the noise source spectra constantly change. Additionally, we present accurate results for the behavior of footstep signal reduction versus distance for a moving (walking/running) person and the seismic sensors. The effects of seismic signal summation and the noise associated with a number of sensors in environments such as ledge rock and soft earth surface is also discussed.

  12. Simulated performance of an order statistic threshold strategy for detection of narrowband signals

    NASA Technical Reports Server (NTRS)

    Satorius, E.; Brady, R.; Deich, W.; Gulkis, S.; Olsen, E.

    1988-01-01

    The application of order statistics to signal detection is becoming an increasingly active area of research. This is due to the inherent robustness of rank estimators in the presence of large outliers that would significantly degrade more conventional mean-level-based detection systems. A detection strategy is presented in which the threshold estimate is obtained using order statistics. The performance of this algorithm in the presence of simulated interference and broadband noise is evaluated. In this way, the robustness of the proposed strategy in the presence of the interference can be fully assessed as a function of the interference, noise, and detector parameters.

  13. Multi-frequency phase-coded microwave signal generation based on polarization modulation and balanced detection.

    PubMed

    Zhu, Dan; Xu, Weiyuan; Wei, Zhengwu; Pan, Shilong

    2016-01-01

    Photonic multi-frequency phase-coded microwave signal generation is proposed and demonstrated based on polarization modulation and balanced detection. Consisting of only a polarization modulator (PolM) driven by an electrical coding data, a polarization beam splitter (PBS) and a balanced photodetector (BPD), the proposed microwave phase coder has no requirement on the wavelength, intensity modulation format, or modulation index of the input optical microwave signal, and allows phase coding of arbitrary-format RF signals, which enables multi-frequency phase coding with compact structure, simple operation, and high flexibility. A proof-of-concept experiment is performed, achieving simultaneous phase coding of 15 and 30 GHz, or 10 and 20 GHz RF signals with a coding rate of 5  Gb/s.

  14. Combining eigenvector methods and support vector machines for detecting variability of Doppler ultrasound signals.

    PubMed

    Ubeyli, Elif Derya

    2007-05-01

    In this paper, the multiclass support vector machines (SVMs) with the error correcting output codes (ECOC) were presented for detecting variabilities of the multiclass Doppler ultrasound signals. The ophthalmic arterial (OA) Doppler signals were recorded from healthy subjects, subjects suffering from OA stenosis, subjects suffering from ocular Behcet disease. The internal carotid arterial (ICA) Doppler signals were recorded from healthy subjects, subjects suffering from ICA stenosis, subjects suffering from ICA occlusion. Methods of combining multiple classifiers with diverse features are viewed as a general problem in various application areas of pattern recognition. Because of the importance of making the right decision, better classification procedures for Doppler ultrasound signals are searched. Decision making was performed in two stages: feature extraction by eigenvector methods and classification using the SVMs trained on the extracted features. The research demonstrated that the multiclass SVMs trained on extracted features achieved high accuracy rates. PMID:17289211

  15. Detection of beam induced dipole-mode signals in the SLC S-band structures

    SciTech Connect

    Seidel, M.; Adolphsen, C.; Assmann, R.; Whittum, D.H.

    1997-06-01

    Beam emittance dilution caused by wakefield effects is one of the important issues in the SLC linac. The detection of beam induced dipole mode signals in the C-band range could provide a direct measure of the strength of transverse wakefield kicks the beam experiences in the accelerating structures. The authors investigate the applicability of these microwave signals for the beam steering purposes. The RF distribution system in the linac sectors 2, 6 and 29 has been equipped with a simple experimental setup to observe the beam induced dipole mode signals. The paper discusses the setup, the mode-structure of the observed signals as well as experimental results from beam steering scans, obtained during the 95/96 SLC runs.

  16. Low-cost detection of RC-IED activation signals in VHF band

    NASA Astrophysics Data System (ADS)

    Camargo Suarez, Victor Hugo; Marulanda B., Jose Ignacio

    2014-05-01

    The proliferation of Radio Controlled Improvised Explosive Devices (RC-IED) is a growing threat around the world. The ease of construction and low cost of these devices are transforming common things in lethal tramps. The fight against this threats normally involves the use of sophisticated and expensive equipment of Electronic Warfare based on high speed DSP systems, just to detect the presence of detonation signals. In this work is showed how to find activation signals based on the characteristic of the power in a specific band and the previous knowledge about the detonation signals. As proof of concept we have taken the information about the RC-IEDs used in the Colombian conflict and develop an algorithm to find detonation signals based on the measured power in frequencies between 136 MHz and 174 MHz (2 meter civil band)

  17. Microwave vector signal transmission over an optical fiber based on IQ modulation and coherent detection.

    PubMed

    Chen, Yang; Shao, Tong; Wen, Aijun; Yao, Jianping

    2014-03-15

    A novel approach to transmitting two vector signals using a single optical carrier based on IQ modulation and coherent detection is proposed and demonstrated. In the proposed system, two quadrature phase-shift keying (QPSK) signals are IQ modulated on an optical carrier with one polarization state using a dual-parallel Mach-Zehnder modulator (DP-MZM). The optical carrier with an orthogonal polarization state is not modulated but transmitted with the modulated optical wave. At the receiver, the two orthogonally polarized light waves are separated and sent to a coherent detector, where the two QPSK signals are separated and demodulated. An experiment is performed. The transmission of two QPSK signals at 2 GHz with a data rate of 1 Gbps is implemented over a 25 km single-mode fiber. The performance of the transmission in terms of error vector magnitude is evaluated.

  18. Factors influencing the detectability of early warning signals of population collapse.

    PubMed

    Clements, Christopher F; Drake, John M; Griffiths, Jason I; Ozgul, Arpat

    2015-07-01

    The recent description of potentially generic early warning signals is a promising development that may help conservationists to anticipate a population's collapse prior to its occurrence. So far, the majority of such warning signals documented have been in highly controlled laboratory systems or in theoretical models. Data from wild populations, however, are typically restricted both temporally and spatially due to limited monitoring resources and intrinsic ecological heterogeneity-limitations that may affect the detectability of generic early warning signals, as they add additional stochasticity to population abundance estimates. Consequently, spatial and temporal subsampling may serve to either muffle or magnify early warning signals. Using a combination of theoretical models and analysis of experimental data, we evaluate the extent to which statistical warning signs are robust to data corruption.

  19. Detecting missing signals in multichannel recordings by using higher order statistics.

    PubMed

    Halabi, R; Diab, M O; Moslem, B; Khalil, M; Marque, C

    2012-01-01

    In real world applications, a multichannel acquisition system is susceptible of having one or many of its sensors displaced or detached, leading therefore to the loss or corruption of the recorded signals. In this paper, we present a technique for detecting missing or corrupted signals in multichannel recordings. Our approach is based on Higher Order Statistics (HOS) analysis. Our approach is tested on real uterine electromyogram (EMG) signals recorded by 4×4 electrode grid. Results have shown that HOS descriptors can discriminate between the two classes of signals (missing vs. non-missing). These results are supported by statistical analysis using the t-test which indicated good statistical significance of 95% confidence level.

  20. Computational approaches for pharmacovigilance signal detection: toward integrated and semantically-enriched frameworks.

    PubMed

    Koutkias, Vassilis G; Jaulent, Marie-Christine

    2015-03-01

    Computational signal detection constitutes a key element of postmarketing drug monitoring and surveillance. Diverse data sources are considered within the 'search space' of pharmacovigilance scientists, and respective data analysis methods are employed, all with their qualities and shortcomings, towards more timely and accurate signal detection. Recent systematic comparative studies highlighted not only event-based and data-source-based differential performance across methods but also their complementarity. These findings reinforce the arguments for exploiting all possible information sources for drug safety and the parallel use of multiple signal detection methods. Combinatorial signal detection has been pursued in few studies up to now, employing a rather limited number of methods and data sources but illustrating well-promising outcomes. However, the large-scale realization of this approach requires systematic frameworks to address the challenges of the concurrent analysis setting. In this paper, we argue that semantic technologies provide the means to address some of these challenges, and we particularly highlight their contribution in (a) annotating data sources and analysis methods with quality attributes to facilitate their selection given the analysis scope; (b) consistently defining study parameters such as health outcomes and drugs of interest, and providing guidance for study setup; (c) expressing analysis outcomes in a common format enabling data sharing and systematic comparisons; and (d) assessing/supporting the novelty of the aggregated outcomes through access to reference knowledge sources related to drug safety. A semantically-enriched framework can facilitate seamless access and use of different data sources and computational methods in an integrated fashion, bringing a new perspective for large-scale, knowledge-intensive signal detection.

  1. From social-signal detection to higher social cognition: an fMRI approach.

    PubMed

    Sugiura, Motoaki; Yomogida, Yukihito; Mano, Yoko; Sassa, Yuko; Kambara, Toshimune; Sekiguchi, Atsushi; Kawashima, Ryuta

    2014-09-01

    Implicit or automatic detection of social signals, which discriminate animate, intentional objects in the environment, is essential for higher social cognition and its development. Using functional magnetic resonance imaging, we identified the neural substrate of detecting simple visual social signals and examined its functional link with the mechanism of inferring another's mental state. Healthy participants were presented with the eye-gaze shift (EG) and self-propelling motion (SP) under both implicit and explicit task conditions. They also performed a social role-playing game in which mental inference (MI) was implicitly prompted during the presentation of faces (implicit MI). Implicit detection of EG and SP activated the posterior middle temporal gyrus (pMTG) bilaterally, whereas the right posterior superior temporal sulcus was activated during the explicit conditions. We revealed that the individual variation in neural response in the right pMTG during implicit eye-gaze detection explains the individual tendency to recruit the regions implicated in mental-state inference (medial prefrontal cortex, temporal pole and striatum) during the implicit MI task. Our results suggest that the implicit detection of visual social signals involves the pMTG and underlies the development of higher social cognition. PMID:23887806

  2. Developmental hearing loss impairs signal detection in noise: putative central mechanisms

    PubMed Central

    Gay, Jennifer D.; Voytenko, Sergiy V.; Galazyuk, Alexander V.; Rosen, Merri J.

    2014-01-01

    Listeners with hearing loss have difficulty processing sounds in noisy environments. This is most noticeable for speech perception, but is reflected in a basic auditory processing task: detecting a tonal signal in a noise background, i.e., simultaneous masking. It is unresolved whether the mechanisms underlying simultaneous masking arise from the auditory periphery or from the central auditory system. Poor detection in listeners with sensorineural hearing loss (SNHL) is attributed to cochlear hair cell damage. However, hearing loss alters neural processing in the central auditory system. Additionally, both psychophysical and neurophysiological data from normally hearing and impaired listeners suggest that there are additional contributions to simultaneous masking that arise centrally. With SNHL, it is difficult to separate peripheral from central contributions to signal detection deficits. We have thus excluded peripheral contributions by using an animal model of early conductive hearing loss (CHL) that provides auditory deprivation but does not induce cochlear damage. When tested as adults, animals raised with CHL had increased thresholds for detecting tones in simultaneous noise. Furthermore, intracellular in vivo recordings in control animals revealed a cortical correlate of simultaneous masking: local cortical processing reduced tone-evoked responses in the presence of noise. This raises the possibility that altered cortical responses which occur with early CHL can influence even simple signal detection in noise. PMID:25249949

  3. Label-acquired magnetorotation as a signal transduction method for protein detection: aptamer-based detection of thrombin

    PubMed Central

    Hecht, Ariel; Akshay Kumar, Anand; Kopelman, Raoul

    2011-01-01

    This paper presents a new signal transduction method, called Label-Acquired Magnetorotation (LAM), for the measurement of proteins in solution. We demonstrate the use of LAM to detect the protein thrombin using aptamers, with an LOD (limit of detection) of 300 pM. LAM is modeled after a sandwich assay, with a 10 µm nonmagnetic “mother” sphere as the capture component, and with 1 µm magnetic “daughter” beads as the labels. The protein-mediated attachment of daughter beads to the mother sphere forms a rotating sandwich complex. In a rotating magnetic field, the rotational frequency of a sandwich complex scales with the number of attached magnetic beads, which scales with the concentration of the protein present in solution. This paper represents the first instance of the detection of a protein using LAM. PMID:21805996

  4. Asymmetric signal amplification for simultaneous SERS detection of multiple cancer markers with significantly different levels.

    PubMed

    Ye, Sujuan; Wu, Yanying; Zhai, Xiaomo; Tang, Bo

    2015-08-18

    Simultaneous detection of cancer biomarkers holds great promise for the early diagnosis of different cancers. However, in the presence of high-concentration biomarkers, the signals of lower-expression biomarkers are overlapped. Existing techniques are not suitable for simultaneously detecting multiple biomarkers at concentrations with significantly different orders of magnitude. Here, we propose an asymmetric signal amplification method for simultaneously detecting multiple biomarkers with significantly different levels. Using the bifunctional probe, a linear amplification mode responds to high-concentration markers, and quadratic amplification mode responds to low-concentration markers. With the combined biobarcode probe and hybridization chain reaction (HCR) amplification method, the detection limits of microRNA (miRNA) and ATP via surface-enhanced Raman scattering (SERS) detection are 0.15 fM and 20 nM, respectively, with a breakthrough of detection concentration difference over 11 orders of magnitude. Furthermore, successful determination of miRNA and ATP in cancer cells supports the practicability of the assay. This methodology promises to open an exciting new avenue for the detection of various types of biomolecules. PMID:26218034

  5. Improved detection of magnetic signals by a MEMS sensor using stochastic resonance.

    PubMed

    Herrera-May, Agustín L; Tapia, Jesus A; Domínguez-Nicolás, Saúl M; Juarez-Aguirre, Raul; Gutierrez-D, Edmundo A; Flores, Amira; Figueras, Eduard; Manjarrez, Elias

    2014-01-01

    We introduce the behavior of the electrical output response of a magnetic field sensor based on microelectromechanical systems (MEMS) technology under different levels of controlled magnetic noise. We explored whether a particular level of magnetic noise applied on the vicinity of the MEMS sensor can improve the detection of subthreshold magnetic fields. We examined the increase in the signal-to-noise ratio (SNR) of such detected magnetic fields as a function of the magnetic noise intensity. The data disclosed an inverted U-like graph between the SNR and the applied magnetic noise. This finding shows that the application of an intermediate level of noise in the environment of a MEMS magnetic field sensor improves its detection capability of subthreshold signals via the stochastic resonance phenomenon.

  6. High efficiency processing for reduced amplitude zones detection in the HRECG signal

    NASA Astrophysics Data System (ADS)

    Dugarte, N.; Álvarez, A.; Balacco, J.; Mercado, G.; Gonzalez, A.; Dugarte, E.; Olivares, A.

    2016-04-01

    Summary - This article presents part of a more detailed research proposed in the medium to long term, with the intention of establishing a new philosophy of electrocardiogram surface analysis. This research aims to find indicators of cardiovascular disease in its early stage that may go unnoticed with conventional electrocardiography. This paper reports the development of a software processing which collect some existing techniques and incorporates novel methods for detection of reduced amplitude zones (RAZ) in high resolution electrocardiographic signal (HRECG).The algorithm consists of three stages, an efficient processing for QRS detection, averaging filter using correlation techniques and a step for RAZ detecting. Preliminary results show the efficiency of system and point to incorporation of techniques new using signal analysis with involving 12 leads.

  7. High efficiency processing for reduced amplitude zones detection in the HRECG signal

    NASA Astrophysics Data System (ADS)

    Dugarte, N.; Álvarez, A.; Balacco, J.; Mercado, G.; Gonzalez, A.; Dugarte, E.; Olivares, A.

    2016-04-01

    Summary – This article presents part of a more detailed research proposed in the medium to long term, with the intention of establishing a new philosophy of electrocardiogram surface analysis. This research aims to find indicators of cardiovascular disease in its early stage that may go unnoticed with conventional electrocardiography. This paper reports the development of a software processing which collect some existing techniques and incorporates novel methods for detection of reduced amplitude zones (RAZ) in high resolution electrocardiographic signal (HRECG).The algorithm consists of three stages, an efficient processing for QRS detection, averaging filter using correlation techniques and a step for RAZ detecting. Preliminary results show the efficiency of system and point to incorporation of techniques new using signal analysis with involving 12 leads.

  8. Improved detection of magnetic signals by a MEMS sensor using stochastic resonance.

    PubMed

    Herrera-May, Agustín L; Tapia, Jesus A; Domínguez-Nicolás, Saúl M; Juarez-Aguirre, Raul; Gutierrez-D, Edmundo A; Flores, Amira; Figueras, Eduard; Manjarrez, Elias

    2014-01-01

    We introduce the behavior of the electrical output response of a magnetic field sensor based on microelectromechanical systems (MEMS) technology under different levels of controlled magnetic noise. We explored whether a particular level of magnetic noise applied on the vicinity of the MEMS sensor can improve the detection of subthreshold magnetic fields. We examined the increase in the signal-to-noise ratio (SNR) of such detected magnetic fields as a function of the magnetic noise intensity. The data disclosed an inverted U-like graph between the SNR and the applied magnetic noise. This finding shows that the application of an intermediate level of noise in the environment of a MEMS magnetic field sensor improves its detection capability of subthreshold signals via the stochastic resonance phenomenon. PMID:25329563

  9. Activity pattern detection in electroneurographic and electromyogram signals through a heteroscedastic change-point method.

    PubMed

    Esquivel-Frausto, M E; Guerrero, J A; Macías-Díaz, J E

    2010-04-01

    In this work, we propose a heteroscedastic method in the detection of activity patterns of electroneurographic and electromyogram signals involved in rhythmic activities of nerves and muscles, respectively. The electric behavior observed in such signals is characterized by phases of activity and silence. The beginning and the length of electrically active and electrically silent phases in a signal allow us to quantitatively analyze the changes and the effects on a rhythmic activity produced by experimental changes. In order to distinguish between these two phases, signals are assumed to be a sample of a time-dependent, normally distributed random variable with non-constant variance, and that the determination of the variance at each point allows us to determine in which phase is the signal. The parameters of the model are determined by means of an iterative process which maximizes the log-likelihood under the proposed model. Moreover, we apply our method to the determination of the activity phases and silence phases in sequences of experimental and synthetic electroneurographic and electromyogram signals. The results obtained with synthetic data show that the method performs well in the determination of these activity patterns. Finally, the study of particular signals simulated under a generalized autoregressive conditional heteroscedasticity model suggests the robustness of the method with respect to the assumption of independence.

  10. Remote heartbeat signal detection from visible spectrum recordings based on blind deconvolution

    NASA Astrophysics Data System (ADS)

    Kaur, Balvinder; Moses, Sophia; Luthra, Megha; Ikonomidou, Vasiliki N.

    2016-05-01

    While recent advances have shown that it is possible to acquire a signal equivalent to the heartbeat from visual spectrum video recordings of the human skin, extracting the heartbeat's exact timing information from it, for the purpose of heart rate variability analysis, remains a challenge. In this paper, we explore two novel methods to estimate the remote cardiac signal peak positions, aiming at a close representation of the R-peaks of the ECG signal. The first method is based on curve fitting (CF) using a modified filtered least mean square (LMS) optimization and the second method is based on system estimation using blind deconvolution (BDC). To prove the efficacy of the developed algorithms, we compared results obtained with the ground truth (ECG) signal. Both methods achieved a low relative error between the peaks of the two signals. This work, performed under an IRB approved protocol, provides initial proof that blind deconvolution techniques can be used to estimate timing information of the cardiac signal closely correlated to the one obtained by traditional ECG. The results show promise for further development of a remote sensing of cardiac signals for the purpose of remote vital sign and stress detection for medical, security, military and civilian applications.

  11. Spatial selectivity and binaural responses in the inferior colliculus of the great horned owl.

    PubMed

    Volman, S F; Konishi, M

    1989-09-01

    In this study we have investigated the processing of auditory cues for sound localization in the great horned owl (Bubo virginianus). Previous studies have shown that the barn owl, whose ears are asymmetrically oriented in the vertical plane, has a 2-dimensional, topographic representation of auditory space in the external division of the inferior colliculus (ICx). As in the barn owl, the great horned owl's ICx is anatomically distinct and projects to the optic tectum. Neurons in ICx respond over only a small range of azimuths (mean = 32 degrees), and azimuth is topographically mapped. In contrast to the barn owl, the great horned owl has bilaterally symmetrical ears and its receptive fields are not restricted in elevation. The binaural cues available for sound localization were measured both with cochlear microphonic recordings and with a microphone attached to a probe tube in the auditory canal. Interaural time disparity (ITD) varied monotonically with azimuth. Interaural intensity differences (IID) also changed with azimuth, but the largest IIDs were less than 15 dB, and the variation was not monotonic. Neither ITD nor IID varied systematically with changes in the vertical position of a sound source. We used dichotic stimulation to determine the sensitivity of ICx neurons to these binaural cues. Best ITD of ICx units was topographically mapped and strongly correlated with receptive-field azimuth. The width of ITD tuning curves, measured at 50% of the maximum response, averaged 72 microseconds. All ICx neurons responded only to binaural stimulation and had nonmonotonic IID tuning curves. Best IID was weakly, but significantly, correlated with best ITD (r = 0.39, p less than 0.05). The IID tuning curves, however, were broad (mean 50% width = 24 dB), and 67% of the units had best IIDs within 5 dB of 0 dB IID. ITD tuning was sensitive to variations in IID in the direction opposite to that expected for time-intensity trading, but the magnitude of this effect was only

  12. An electrochemical peptide cleavage-based biosensor for matrix metalloproteinase-2 detection with exonuclease III-assisted cycling signal amplification.

    PubMed

    Wang, Ding; Yuan, Yali; Zheng, Yingning; Chai, Yaqin; Yuan, Ruo

    2016-05-01

    In this work, an electrochemical peptide biosensor was developed for matrix metalloproteinase-2 (MMP-2) detection by conversion of a peptide cleavage event into DNA detection with exonuclease III (Exo III)-assisted cycling signal amplification.

  13. Generalized average of signals (GAS) - a new method for denoising and phase detection

    NASA Astrophysics Data System (ADS)

    Malek, J.; Kolinsky, P.; Strunc, J.; Valenta, J.

    2007-12-01

    A novel method called Generalized Average of Signals (GAS) was developed and tested during the last two years (Málek et al., in press). This method is designed for processing of seismograms from dense seismic arrays and is convenient mainly for denoising and weak phase detection. The main idea of the GAS method is based on non-linear stacking of seismograms in frequency domain, which considerably improves signal-to-noise ratio of coherent seismograms. Several synthetic tests of the GAS method are presented and the results are compared with the PWS method of Schimell and Paulssen (1997). Moreover, examples of application on real data are presented. These examples were chosen to show a broad applicability of the method in experiments of different scales. The first one shows identification of S-waves on seismograms from shallow seismic. The second one concerns identification of converted waves from local earthquakes registered at the WEBNET local network in western Bohemia. Finally, the third one depicts identification of PKIKP onsets on seismograms of teleseismic earthquakes. Schimmel, M., Paulssen H. (1997): Noise reduction and detection of weak, coherent signals through phase- weighted stacks. Geophys. J. Int. 130, 497-505. Málek J., Kolínský P., Strunc J. and Valenta J. (2007): Generalized average of signals (GAS) - a new method for detection of very weak waves in seismograms. Acta Geodyn. et Geomater., in press.

  14. Increasing signal amplitude in fiber Bragg grating detection of Lamb waves using remote bonding.

    PubMed

    Wee, Junghyun; Wells, Brian; Hackney, Drew; Bradford, Philip; Peters, Kara

    2016-07-20

    Networks of fiber Bragg grating (FBG) sensors can serve as structural health monitoring systems for large-scale structures based on the collection of ultrasonic waves. The demodulation of structural Lamb waves using FBG sensors requires a high signal-to-noise ratio because the Lamb waves are of low amplitudes. This paper compares the signal transfer amplitudes between two adhesive mounting configurations for an FBG to detect Lamb waves propagating in an aluminum plate: a directly bonded FBG and a remotely bonded FBG. In the directly bonded FBG case, the Lamb waves create in-plane and out-of-plane displacements, which are transferred through the adhesive bond and detected by the FBG sensor. In the remotely bonded FBG case, the Lamb waves are converted into longitudinal and flexural traveling waves in the optical fiber at the adhesive bond, which propagate through the optical fiber and are detected by the FBG sensor. A theoretical prediction of overall signal attenuation also is performed, which is the combination of material attenuation in the plate and optical fiber and attenuation due to wave spreading in the plate. The experimental results demonstrate that remote bonding of the FBG significantly increases the signal amplitude measured by the FBG.

  15. A capillary-based probe for in situ detection of enhanced fluorescence signals

    NASA Astrophysics Data System (ADS)

    Long, F.; Xiao, R.; Zhu, A. N.; Shi, H. C.; Wang, S. Q.

    2013-07-01

    A simple, compact, and high sensitivity capillary-based probe for the in situ detection of fluorescence signals with high sensitivity is demonstrated. A home-made single-multi-mode fiber coupler that is coaxially aligned with the capillary-based probe provides for the transmission of excitation light and the collection and transmission of fluorescence. We propose a conceptually straightforward theoretical model to optimize the factors affecting the fluorescence-capture capability of the capillary-based probe. The fluorescence signal detected by fiber-optic spectroscopy non-linearly increases with the length of the capillary-based probe. In addition, the thicker the capillary tube wall is, the less the fluorescence signals determined are. The performance of the proposed probe is evaluated experimentally by measuring the fluorescence spectra of Cy5.5 dye and blue-green algae. The experimental results show that the proposed probe provides more than a ten-fold increase in fluorescence signal compared with direct measurements by a flat-tipped multi-mode fiber probe. The advantages of the capillary-based probe, which include its simple and compact structure, excellent light collection efficiency, requirement of small sample volume, and recoverability of samples, allow its wide application to in situ detection in the medical, forensic, biological, geological, and environmental fields with high sensitivity.

  16. A low-complex multi-channel methodology for noise detection in phonocardiogram signals.

    PubMed

    Nunes, Diogo; Leal, Adriana; Couceiro, Ricardo; Henriques, Jorge; Mendes, Luís; Carvalho, Paulo; Teixeira, César

    2015-01-01

    The phonocardiography (PCG) is an important technique for the diagnosis of several heart conditions. However, the PCG signal is highly prone to noise, which can be an obstacle for the detection and interpretation of physiological heart sounds. Thus, the detection and elimination of noise present in PCG signals is crucial for the accurate analysis of heart sounds, especially in p-health environments. Noise can be introduced by various internal factors (e.g., respiration and laughing) and by external conditions (e.g., phone ringing or door closing). To mention also that the noise frequency components are typically overlapped with the PCG spectrum, increasing the complexity of the analysis. The purpose of the present work consists in the detection of noisy periods willfully introduced during the performance of three different sets of tasks. The developed method returns the classification of the signal content, in a window-by-window analysis and can be divided in two distinct phases. The first step consists in the search for a noise free window using a feature obtained from the PCG time-domain. In the second step, the noise free window is compared with the remaining signal. The classification between clean and contaminated PCG is performed using two features from the frequency domain. The algorithm was able to discriminate clean from contamined PCG sections with an average sensitivity and specificity of 95.59% and 92.68%, respectively.

  17. Increasing signal amplitude in fiber Bragg grating detection of Lamb waves using remote bonding.

    PubMed

    Wee, Junghyun; Wells, Brian; Hackney, Drew; Bradford, Philip; Peters, Kara

    2016-07-20

    Networks of fiber Bragg grating (FBG) sensors can serve as structural health monitoring systems for large-scale structures based on the collection of ultrasonic waves. The demodulation of structural Lamb waves using FBG sensors requires a high signal-to-noise ratio because the Lamb waves are of low amplitudes. This paper compares the signal transfer amplitudes between two adhesive mounting configurations for an FBG to detect Lamb waves propagating in an aluminum plate: a directly bonded FBG and a remotely bonded FBG. In the directly bonded FBG case, the Lamb waves create in-plane and out-of-plane displacements, which are transferred through the adhesive bond and detected by the FBG sensor. In the remotely bonded FBG case, the Lamb waves are converted into longitudinal and flexural traveling waves in the optical fiber at the adhesive bond, which propagate through the optical fiber and are detected by the FBG sensor. A theoretical prediction of overall signal attenuation also is performed, which is the combination of material attenuation in the plate and optical fiber and attenuation due to wave spreading in the plate. The experimental results demonstrate that remote bonding of the FBG significantly increases the signal amplitude measured by the FBG. PMID:27463905

  18. Signal Detection of Adverse Drug Reaction of Amoxicillin Using the Korea Adverse Event Reporting System Database

    PubMed Central

    2016-01-01

    We conducted pharmacovigilance data mining for a β-lactam antibiotics, amoxicillin, and compare the adverse events (AEs) with the drug labels of 9 countries including Korea, USA, UK, Japan, Germany, Swiss, Italy, France, and Laos. We used the Korea Adverse Event Reporting System (KAERS) database, a nationwide database of AE reports, between December 1988 and June 2014. Frequentist and Bayesian methods were used to calculate disproportionality distribution of drug-AE pairs. The AE which was detected by all the three indices of proportional reporting ratio (PRR), reporting odds ratio (ROR), and information component (IC) was defined as a signal. The KAERS database contained a total of 807,582 AE reports, among which 1,722 reports were attributed to amoxicillin. Among the 192,510 antibiotics-AE pairs, the number of amoxicillin-AE pairs was 2,913. Among 241 AEs, 52 adverse events were detected as amoxicillin signals. Comparing the drug labels of 9 countries, 12 adverse events including ineffective medicine, bronchitis, rhinitis, sinusitis, dry mouth, gastroesophageal reflux, hypercholesterolemia, gastric carcinoma, abnormal crying, induration, pulmonary carcinoma, and influenza-like symptoms were not listed on any of the labels of nine countries. In conclusion, we detected 12 new signals of amoxicillin which were not listed on the labels of 9 countries. Therefore, it should be followed by signal evaluation including causal association, clinical significance, and preventability. PMID:27510377

  19. Methods of electroencephalographic signal analysis for detection of small hidden changes.

    PubMed

    Hinrikus, Hiie; Bachmann, Maie; Kalda, Jaan; Sakki, Maksim; Lass, Jaanus; Tomson, Ruth

    2007-01-01

    The aim of this study was to select and evaluate methods sensitive to reveal small hidden changes in the electroencephalographic (EEG) signal. Two original methods were considered.Multifractal method of scaling analysis of the EEG signal based on the length distribution of low variability periods (LDLVP) was developed and adopted for EEG analysis. The LDLVP method provides a simple route to detecting the multifractal characteristics of a time-series and yields somewhat better temporal resolution than the traditional multifractal analysis.The method of modulation with further integration of energy of the recorded signal was applied for EEG analysis. This method uses integration of differences in energy of the EEG segments with and without stressor.Microwave exposure was used as an external stressor to cause hidden changes in the EEG. Both methods were evaluated on the same EEG database. Database consists of resting EEG recordings of 15 subjects without and with low-level microwave exposure (450 MHz modulated at 40 Hz, power density 0.16 mW/cm2). The significant differences between recordings with and without exposure were detected by the LDLVP method for 4 subjects (26.7%) and energy integration method for 2 subjects (13.3%).The results show that small changes in time variability or energy of the EEG signals hidden in visual inspection can be detected by the LDLVP and integration of differences methods. PMID:17908286

  20. Orthogonal sensor suite and the signal-processing algorithm for human detection and discrimination

    NASA Astrophysics Data System (ADS)

    Ekimov, Alexander; Sabatier, James M.

    2009-05-01

    The focus of this paper is a review of methods and algorithms for human motion detection in the presence of nonstationary environmental background noise. Human footstep forces on the ground/floor generate periodic broadband seismic and sound signals envelopes with two characteristic times, T1 (the footstep repetition time, which is equal to the time of the whole body periodic vibrations) and T2 (the footstep duration time, which is equal to the time interval for a single footstep from "heel strike" to "toe slap and weight transfer"). Human body motions due to walking are periodic movements of a multiple-degrees-of-freedom mechanical system with a specific cadence frequency equal to 1/T1. For a walking human, the cadence frequencies for the appendages are the same and lie below 3 Hz. Simultaneously collecting footstep seismic, ultrasonic, and Doppler signals of human motion enhance the capability to detect humans in quiet and noisy environments. The common denominator of in the use of these orthogonal sensors (seismic, ultrasonic, Doppler) is a signal-processing algorithm package that allows detection of human-specific time-frequency signatures and discriminates them using a distinct cadence frequency from signals produced by other moving and stationary objects (e.g. vehicular and animal signatures). It has been experimentally shown that human cadence frequencies for seismic, passive ultrasonic, and Doppler motion signatures are equivalent and temporally stable.

  1. Electrochemical detection of protein kinase activity based on carboxypeptidase Y digestion triggered signal amplification.

    PubMed

    Yin, Huanshun; Wang, Xinxu; Guo, Yunlong; Zhou, Yunlei; Ai, Shiyun

    2015-04-15

    An effective assay method for monitoring protein kinase activity and screening inhibitors is greatly beneficial to kinase-related drug discovery, early diagnosis of diseases, and therapeutic effect evaluation. Herein, we develop a simple electrochemical method for detecting the activity of casein kinase II (CK2) based on phosphorylation against carboxypeptidase Y (CPY) digestion triggered signal amplification, where CK2 catalyzed phosphorylation event protects the substrate peptide from the digestion of CPY, maintains the repulsive force of the substrate peptide towards the redox probe, and results in a weak electrochemical signal. Whereas, without phosphorylation, the substrate peptide is digested by CPY and a strong electrochemical signal is obtained. The detection feasibility is demonstrated for the assay of CK2 activity with low detection limit of 0.047unit/mL. Moreover, the biosensor was used for the analysis of kinase inhibition. Based on the electrochemical signal dependent inhibitor concentration, the IC50 value of ellagic acid was estimated to be 39.77nM. The proposed method is also successfully applied to analyze CK2 activity in cell lysates, proving the applicability in complex biological samples.

  2. Asymptotic ideal observers and surrogate figures of merit for signal detection with list-mode data.

    PubMed

    Clarkson, Eric

    2012-10-01

    The asymptotic form for the likelihood ratio is derived for list-mode data generated by an imaging system viewing a possible signal in a randomly generated background. This calculation provides an approximation to the likelihood ratio that is valid in the limit of large number of list entries, i.e., a large number of photons. These results are then used to derive surrogate figures of merit, quantities that are correlated with ideal-observer performance on detection tasks, as measured by the area under the receiver operating characteristic curve, but are easier to compute. A key component of these derivations is the determination of asymptotic forms for the Fisher information for the signal amplitude in the limit of a large number of counts or a long exposure time. This quantity is useful in its own right as a figure of merit (FOM) for the task of estimating the signal amplitude. The use of the Fisher information in detection tasks is based on the fact that it provides an approximation for ideal-observer detectability when the signal is weak. For both the fixed-count and fixed-time cases, four surrogate figures of merit are derived. Two are based on maximum likelihood reconstructions; one uses the characteristic functional of the random backgrounds. The fourth surrogate FOM is identical in the two cases and involves an integral over attribute space for each of a randomly generated sequence of backgrounds.

  3. Development of a Photon Counting System for Differential Lidar Signal Detection

    NASA Technical Reports Server (NTRS)

    Elsayed-Ali, Hani

    1997-01-01

    Photon counting has been chosen as a means to extend the detection range of current airborne DIAL ozone measurements. Lidar backscattered return signals from the on and off-line lasers experience a significant exponential decay. To extract further data from the decaying ozone return signals, photon counting will be used to measure the low light levels, thus extending the detection range. In this application, photon counting will extend signal measurement where the analog return signal is too weak. The current analog measurement range is limited to approximately 25 kilometers from an aircraft flying at 12 kilometers. Photon counting will be able to exceed the current measurement range so as to follow the mid-latitude model of ozone density as a function of height. This report describes the development of a photon counting system. The initial development phase begins with detailed evaluation of individual photomultiplier tubes. The PMT qualities investigated are noise count rates, single electron response peaks, voltage versus gain values, saturation effects, and output signal linearity. These evaluations are followed by analysis of two distinctive tube base gating schemes. The next phase is to construct and operate a photon counting system in a laboratory environment. The laboratory counting simulations are used to determine optimum discriminator setpoints and to continue further evaluations of PMT properties. The final step in the photon counting system evaluation process is the compiling of photon counting measurements on the existing ozone DIAL laser system.

  4. Efficient detection of a CW signal with a linear frequency drift

    NASA Technical Reports Server (NTRS)

    Swarztrauber, Paul N.; Bailey, David H.

    1989-01-01

    An efficient method is presented for the detection of a continuous wave (CW) signal with a frequency drift that is linear in time. Signals of this type occur in transmissions between any two locations that are accelerating relative to one another, e.g., transmissions from the Voyager spacecraft. We assume that both the frequency and the drift are unknown. We also assume that the signal is weak compared to the Gaussian noise. The signal is partitioned into subsequences whose discrete Fourier transforms provide a sequence of instantaneous spectra at equal time intervals. These spectra are then accumulated with a shift that is proportional to time. When the shift is equal to the frequency drift, the signal to noise ratio increases and detection occurs. Here, we show how to compute these accumulations for many shifts in an efficient manner using a variety of Fast Fourier Transformations (FFT). Computing time is proportional to L log L where L is the length of the time series.

  5. Improving single-trial detection of event-related potentials through artificial deformed signals.

    PubMed

    Cecotti, H; Rivet, B

    2014-01-01

    To propose a reliable and robust Brain-Computer Interface (BCI), efficient machine learning and signal processing methods have to be used. However, it is often necessary to have a sufficient number of labeled brain responses to create a model. A large database that would represent all of the possible variabilities of the signal is not always possible to obtain, because calibration sessions have to be short. In the case of BCIs based on the detection of event-related potentials (ERPs), we propose to tackle this problem by including additional deformed patterns in the training database to increase the number of labeled brain responses. The creation of the additional deformed patterns is based on two approaches: (i) smooth deformation fields, and (ii) right and left shifted signals. The evaluation is performed with data from 10 healthy subjects participating in a P300 speller experiment. The results show that small shifts of the signal allow a better estimation of both spatial filters, and a linear classifier. The best performance, AUC=0.828 ± 0.061, is obtained by combining the smooth deformation fields and the shifts, after spatial filtering, compared to AUC=0.543 ± 0.025, without additional deformed patterns. The results support the conclusion that adding signals with small deformations can significantly improve the performance of single-trial detection when the amount of training data is limited.

  6. [Raman Signal Enhancement for Gas Detection Using a Near Concentric Cavity].

    PubMed

    Yang, De-wang; Guo, Jin-jia; Du, Zeng-feng; Wang, Zhen-nan; Zheng, Rong-er

    2015-03-01

    The detection of dissolved gases in seawater plays an important role in ocean observation and exploration. Raman spectroscopy has a great advantage in simultaneous multiple species detection and is thus regarded as a favorable choice for ocean application. However, its sensitivity remains insufficient, and a demand in enhancements is called! for before putting Raman spectroscopy to actual use in marine studies In this work, we developed a near-concentric cavity, in which laser beam could be trapped and reflected back and forth, for the purpose of intensifying Raman signals. The factors that would influence Raman signals were taken into account. The result show that the smaller angle between collection direction and optical axis of reflection mirror, the stronger the signal and signal to noise ratio (SNR) is. With a collection angle of 30 degrees, our Near-concentric Cavity System managed to raise the SNR to a figure about 16 times larger than that of common methods applying 90 degrees. Moreover, the alignment pattern in our system made it possible to excel concentric cavity with a 3 times larger SNR. Compared with the single-pass Raman signal, the signal intensity of our near-concentric cavity was up to 70 times enhanced. According to the obtained results of CO2 measurement, it can be seen that the new system provides a limit of detection(LOD) for CO2 about 0.19 mg x L(-1) using 3-σ criterion standard, and the LOD of 11.5 μg x L(-1) for CH4 was evaluated with the theoretical cross section values of CO2 and CH4.

  7. A comparison of signal detection between an echolocating dolphin and an optimal receiver.

    PubMed

    Au, W W; Pawloski, D A

    1989-01-01

    An electronic simulated target apparatus was used in a two-experiment study to compare the target detection performance of an echolocating bottlenose dolphin with an optimal receiver. Random Gaussian noise with a relatively flat spectrum from 20 to 160 kHz was used as a masking source. Experiment I was conducted to establish a technique for estimating the echo energy-to-noise ratio, Ee/N, at the dolphin's threshold of detection. Dolphins typically vary the amplitude of their emitted signal over a large range making it difficult to estimate Ee/N. In the first part of experiment I, the simulated echo was a double click, the pulses separated by 200 microseconds, with each pulse being a replica of the dolphin's transmitted signal. A staircase psychophysical procedure was used to obtain the detection threshold, and the echo energy-to-noise ratio based on the highest amplitude click emitted per trial, (Ee/N)max, was determined at each reversal point. The second echo type consisted of one of the animal's echolocation clicks, previously measured, digitized and stored in an erasable programmable read-only memory (EPROM). The electronic target simulator was modified so that every time the dolphin emitted an echolocation signal, the EPROM was triggered to produce two pulses separated by 200 microseconds. On any trial, the EPROM signal was played back at a fixed amplitude, regardless of the amplitude of the dolphin's emitted signal. The Ee/N obtained with the EPROM signal at threshold was found to be 2.9 dB lower than (Ee/N)max obtained with the normal phantom target. Therefore an estimate of Ee/N can be obtained by subtracting 2.9 dB from (Ee/N)max.(ABSTRACT TRUNCATED AT 250 WORDS)

  8. Is local myocardial contractility related to endocardial acceleration signals detected by a transvenous pacing lead?

    PubMed

    Bongiorni, M G; Soldati, E; Arena, G; Quirino, G; Vernazza, F; Bernasconi, A; Garberoglio, B

    1996-11-01

    The availability of sensors monitoring cardiac function parameters may offer many interesting new applications in cardiac pacing. A microaccelerometer sensor (BEST, Biomechanical Endocardial Sorin Transducer) located at the tip of a pacing lead (PL) has been developed by Sorin Biomedica. The signal detected by the accelerometer, peak endocardial acceleration (PEA), was shown to reflect cardiac contractility and to be related to the dP/dt signal. Whether the PEA detected by the BEST sensor in different cardiac locations is the expression of local acceleration forces or reflects the whole heart contractility has not yet been demonstrated in humans. Endocardial acceleration and PEA were evaluated in five patients (4 males, 1 female, mean age 68 years) who underwent cardiac catheterization. Sinus rhythm was present in four patients and chronic atrial fibrillation was present in one. The BEST PL was introduced through the left subclavian vein and PEA signals were recorded: (1) at the apex of the right ventricle (RV), (2) within the coronary sinus (CS), (3) at the right atrial appendage (RAA), and (4) floating in the right atrium. The PEA signals were recorded simultaneously with surface ECG, intracardiac electrograms, and RV pressure. At each recording site, PEA signals with significant amplitude were always recorded during the preejection period, during the isovolumic contraction phase, independently of the recording site and cardiac rhythm. The PEA amplitude was higher in the RV (mean value 1.32 g) and it decreased in the RAA and CS (0.75 and 0.45 g, respectively). The same behavior of PEA was observed during sinus rhythm or atrial fibrillation. The amplitude and the timing of the PEA signals detected by the BEST accelerometer were independent of the recording site and atrial rhythm; they appeared to be strictly related to the global ventricular contractility. These results suggest that the BEST could be used either as an effective sensor in closed loop pacing systems

  9. Computer-aided detection of microcalcifications in digital breast tomosynthesis (DBT): a multichannel signal detection approach on projection views

    NASA Astrophysics Data System (ADS)

    Wei, Jun; Chan, Heang-Ping; Hadjiiski, Lubomir; Helvie, Mark A.; Zhou, Chuan; Lu, Yao

    2012-03-01

    DBT is one of the promising imaging modalities that may improve the sensitivity and specificity for breast cancer detection. We are developing a computer-aided detection (CADe) system for clustered microcalcifications (MC) in DBT. A data set of two-view DBTs from 42 breasts was collected with a GE prototype system. We investigated a 2D approach to MC detection using projection view (PV) images rather than reconstructed 3D DBT volume. Our 2D approach consisted of two major stages: 1) detecting individual MC candidates on each PV, and 2) correlating the MC candidates from the different PVs and detecting clusters in the breast volume. With the MC candidates detected by prescreening on PVs, a trained multi-channel (MCH) filter bank was used to extract signal response from each MC candidate. A ray-tracing process was performed to fuse the MCH responses and localize the MC candidates in 3D using the geometrical information of the DBT system. Potential MC clusters were then identified by dynamic clustering of the MCs in 3D. A two-fold cross-validation method was used to train and test the CADe system. The detection performance of clustered MCs was assessed by free receiver operating characteristic (FROC) analysis. It was found that the CADe system achieved a case-based sensitivity of 90% at an average false positive rate of 2.1 clusters per DBT volume. Our study demonstrated that the CADe system using 2D MCH filter bank is promising for detection of clustered MCs in DBT.

  10. Detection of emetic activity in the cat by monitoring venous pressure and audio signals

    NASA Technical Reports Server (NTRS)

    Nagahara, A.; Fox, Robert A.; Daunton, Nancy G.; Elfar, S.

    1991-01-01

    To investigate the use of audio signals as a simple, noninvasive measure of emetic activity, the relationship between the somatic events and sounds associated with retching and vomiting was studied. Thoracic venous pressure obtained from an implanted external jugular catheter was shown to provide a precise measure of the somatic events associated with retching and vomiting. Changes in thoracic venous pressure monitored through an indwelling external jugular catheter with audio signals, obtained from a microphone located above the animal in a test chamber, were compared. In addition, two independent observers visually monitored emetic episodes. Retching and vomiting were induced by injection of xylazine (0.66mg/kg s.c.), or by motion. A unique audio signal at a frequency of approximately 250 Hz is produced at the time of the negative thoracic venous pressure change associated with retching. Sounds with higher frequencies (around 2500 Hz) occur in conjunction with the positive pressure changes associated with vomiting. These specific signals could be discriminated reliably by individuals reviewing the audio recordings of the sessions. Retching and those emetic episodes associated with positive venous pressure changes were detected accurately by audio monitoring, with 90 percent of retches and 100 percent of emetic episodes correctly identified. Retching was detected more accurately (p is less than .05) by audio monitoring than by direct visual observation. However, with visual observation a few incidents in which stomach contents were expelled in the absence of positive pressure changes or detectable sounds were identified. These data suggest that in emetic situations, the expulsion of stomach contents may be accomplished by more than one neuromuscular system and that audio signals can be used to detect emetic episodes associated with thoracic venous pressure changes.

  11. Detection and Quantification of Intracellular Signaling Using FRET-Based Biosensors and High Content Imaging.

    PubMed

    Halls, Michelle L; Poole, Daniel P; Ellisdon, Andrew M; Nowell, Cameron J; Canals, Meritxell

    2015-01-01

    Förster resonance energy transfer (FRET) biosensors represent invaluable tools to detect the spatiotemporal context of second messenger production and intracellular signaling that cannot be attained using traditional methods. Here, we describe a detailed protocol for the use of high content imaging in combination with FRET biosensors to assess second messenger production and intracellular signaling in a time-effective manner. We use four different FRET biosensors to measure cAMP levels, kinase (ERK and PKC), and GTPase activity. Importantly, we provide the protocols to express and measure these sensors in a variety of model cell lines and primary dorsal root ganglia neurons.

  12. Online detection of the modality of complex-valued real world signals.

    PubMed

    Mandic, Danilo P; Vayanos, Phebe; Chen, Mo; Goh, Su Lee

    2008-04-01

    A novel method for the online detection of the modality of complex-valued nonlinear and nonstationary signals is introduced. This is achieved using a convex combination of complex nonlinear adaptive filters with different transient characteristics. To facilitate the online mode of operation, the convex mixing parameter lambda within the proposed architecture is made gradient adaptive. Our focus is on the most important aspect of complex nonlinear modeling, that is, the identification of the split-complex and fully-complex nature of the signal in hand. The algorithms derived are robust and capable of tracking the changes in the modality of both benchmark and real world radar and wind complex vector fields.

  13. Stream computing for biomedical signal processing: A QRS complex detection case-study.

    PubMed

    Murphy, B M; O'Driscoll, C; Boylan, G B; Lightbody, G; Marnane, W P

    2015-01-01

    Recent developments in "Big Data" have brought significant gains in the ability to process large amounts of data on commodity server hardware. Stream computing is a relatively new paradigm in this area, addressing the need to process data in real time with very low latency. While this approach has been developed for dealing with large scale data from the world of business, security and finance, there is a natural overlap with clinical needs for physiological signal processing. In this work we present a case study of streams processing applied to a typical physiological signal processing problem: QRS detection from ECG data. PMID:26737641

  14. Detection and Quantification of Intracellular Signaling Using FRET-Based Biosensors and High Content Imaging.

    PubMed

    Halls, Michelle L; Poole, Daniel P; Ellisdon, Andrew M; Nowell, Cameron J; Canals, Meritxell

    2015-01-01

    Förster resonance energy transfer (FRET) biosensors represent invaluable tools to detect the spatiotemporal context of second messenger production and intracellular signaling that cannot be attained using traditional methods. Here, we describe a detailed protocol for the use of high content imaging in combination with FRET biosensors to assess second messenger production and intracellular signaling in a time-effective manner. We use four different FRET biosensors to measure cAMP levels, kinase (ERK and PKC), and GTPase activity. Importantly, we provide the protocols to express and measure these sensors in a variety of model cell lines and primary dorsal root ganglia neurons. PMID:26260599

  15. Radio signal anomalies detected with MEXART in 2012 during the recovery phase of geomagnetic storms

    NASA Astrophysics Data System (ADS)

    Carrillo-Vargas, Armando; Pérez-Enríquez, Román; López-Montes, Rebeca; Rodríguez-Martínez, Mario; Ugalde-Calvillo, Luis Gerardo

    2016-11-01

    In this work we present MEXART observations in 2012 from 17 radio sources in which we detected anomalies in the radio signal of these sources occurring during the recovery phase of some geomagnetic storms. We performed FFT and wavelet analysis of the radio signals during these periods and found that rather than IPS the anomalies seem to originate in the ionosphere, especially because of the frequencies at which they are observed. We discuss this results under the view that the source of the geomagnetic storm is no longer in the interplanetary medium.

  16. Stream computing for biomedical signal processing: A QRS complex detection case-study.

    PubMed

    Murphy, B M; O'Driscoll, C; Boylan, G B; Lightbody, G; Marnane, W P

    2015-01-01

    Recent developments in "Big Data" have brought significant gains in the ability to process large amounts of data on commodity server hardware. Stream computing is a relatively new paradigm in this area, addressing the need to process data in real time with very low latency. While this approach has been developed for dealing with large scale data from the world of business, security and finance, there is a natural overlap with clinical needs for physiological signal processing. In this work we present a case study of streams processing applied to a typical physiological signal processing problem: QRS detection from ECG data.

  17. Mass detection on mammograms: signal variations and performance changes for human and model observers

    NASA Astrophysics Data System (ADS)

    Castella, C.; Kinkel, K.; Eckstein, M. P.; Abbey, C. K.; Verdun, F. R.; Saunders, R. S.; Samei, E.; Bochud, F. O.

    2008-03-01

    We studied the influence of signal variability on human and model observer performances for a detection task with mammographic backgrounds and computer generated clustered lumpy backgrounds (CLB). We used synthetic yet realistic masses and backgrounds that have been validated by radiologists during previous studies, ensuring conditions close to the clinical situation. Four trained non-physician observers participated in two-alternative forced-choice (2-AFC) experiments. They were asked to detect synthetic masses superimposed on real mammographic backgrounds or CLB. Separate experiments were conducted with sets of benign and malignant masses. Results under the signal-known-exactly (SKE) paradigm were compared with signal-known-statistically (SKS) experiments. In the latter case, the signal was chosen randomly for each of the 1,400 2-AFC trials (image pairs) among a set of 50 masses with similar dimensions, and the observers did not know which signal was present. Human observers' results were then compared with model observers (channelized Hotelling with Difference-of-Gaussian and Gabor channels) in the same experimental conditions. Results show that the performance of the human observers does not differ significantly when benign masses are superimposed on real images or on CLB with locally matched gray level mean and standard deviation. For both benign and malignant masses, the performance does not differ significantly between SKE and SKS experiments, when the signals' dimensions do not vary throughout the experiment. However, there is a performance drop when the SKS signals' dimensions vary from 5.5 to 9.5 mm in the same experiment. Noise level in the model observers can be adjusted to reproduce human observers' proportion of correct answers in the 2-AFC task within 5% accuracy for most conditions.

  18. Polydimethylsiloxane microfluidic chemiluminescence immunodevice with the signal amplification strategy for sensitive detection of human immunoglobin G.

    PubMed

    Li, Huifang; Zhao, Mei; Liu, Wei; Chu, Weiru; Guo, Yumei

    2016-01-15

    A polydimethylsiloxane (PDMS) microfluidic chemiluminescence (CL) immunodevice for sensitive detection of human immunoglobin G (IgG) with the signal amplification strategy was developed in this work. The immunodevice was prepared by covalently immobilizing capture antibodies (Abs) on the silanized microchannel of microfluidic chip. Gold nanoparticles (AuNPs) functionalized with a high molar ratio of horseradish peroxidase (HRP) were used as an Ab label for signal amplification. Using a sandwich immunoassay, the multi-HRP conjugated AuNPs can catalyze the luminol-H2O2 CL system to achieve the high sensitivity. In addition, the double spiral flow-channel was adopted here, which can still contribute to the high sensitivity. Based on signal amplification strategy, the performance of human IgG tests revealed a lower detection limit (DL) of 0.03ng/mL and showed an increase of 7.4-fold in detection sensitivity compared to a commercial Ab-HRP conjugation. This microfluidic immunodevice can provide an alternative approach for sensitive detection of human IgG in the field of clinic diagnostic and therapeutic. PMID:26592629

  19. Real-time bicycle detection at signalized intersections using thermal imaging technology

    NASA Astrophysics Data System (ADS)

    Collaert, Robin

    2013-02-01

    More and more governments and authorities around the world are promoting the use of bicycles in cities, as this is healthy for the bicyclist and improves the quality of life in general. Safety and efficiency of bicyclists has become a major focus. To achieve this, there is a need for a smarter approach towards the control of signalized intersections. Various traditional detection technologies, such as video, microwave radar and electromagnetic loops, can be used to detect vehicles at signalized intersections, but none of these can consistently separate bikes from other traffic, day and night and in various weather conditions. As bikes should get a higher priority and also require longer green time to safely cross the signalized intersection, traffic managers are looking for alternative detection systems that can make the distinction between bicycles and other vehicles near the stop bar. In this paper, the drawbacks of a video-based approach are presented, next to the benefits of a thermal-video-based approach for vehicle presence detection with separation of bicycles. Also, the specific technical challenges are highlighted in developing a system that combines thermal image capturing, image processing and output triggering to the traffic light controller in near real-time and in a single housing.

  20. Info-gap robustness of an input signal optimization algorithm for damage detection

    NASA Astrophysics Data System (ADS)

    Pasquali, M.; Stull, C. J.; Farrar, C. R.

    2015-01-01

    Info-Gap Decision Theory is adopted to assess the robustness of a technique aimed at identifying the optimal excitation signal to be used for active sensing approaches to damage detection. Here the term "active sensing" refers to procedures where a known input is applied to the structure to enhance the damage detection process. Given limited system response measurements and ever-present physical limits on the level of excitation, the ultimate goal of the mentioned technique is to improve the detectability of damage by increasing the difference between measured outputs of the undamaged and damaged systems. In particular, a two degree-of-freedom mass-spring-damper system characterized by the presence of a nonlinear stiffness is considered. Uncertainty is introduced to the system in the form of deviations of its parameters (mass, stiffness, damping ratio) from their nominal values. Variations in the performance of the mentioned technique are then evaluated both in terms of changes in the estimated difference between the responses of the damaged and undamaged systems and in terms of deviations of the identified optimal input signal from its nominal estimation. Finally, plots of the performances of the analyzed algorithm for different levels of uncertainty are obtained, enabling a clear evaluation of the risks connected with designing excitation signals for damage detection, when the parameters that dictate system behavior (e.g. stiffness, mass) are poorly characterized or improperly modeled.