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Sample records for binaural signal detection

  1. Leak detection utilizing analog binaural (VLSI) techniques

    NASA Technical Reports Server (NTRS)

    Hartley, Frank T. (Inventor)

    1995-01-01

    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.

  2. Binaural signal analysis of diffuse sound fields

    NASA Astrophysics Data System (ADS)

    Novo, Pedro A.

    2004-10-01

    The simulation and the binaural recording of sounds produced by large crowds and rain impact sounds has produced an unexpected result. The listeners have reported that the auditory events were mainly concentrated to the left and to right, although the sound sources were equally distributed around the listeners. A similar result was reported with binaural recordings of applause. The results of a binaural signal analysis suggest that the key aspect regarding the lateral position dominance of the auditory events is connected to the sections where the cross-correlation coefficient assumes negative values. A comparison between normalized and non-normalized cross-correlation function predictions indicates that the latter is a better predictor for the cases studied. An adaptation period of several seconds was reported by several listeners. It is suggested that this adaptation period is related to the variations of the cross-correlation, which only average out after, approximately 2 s. The binaural impulse responses of a concert hall at two different listener positions have been analyzed in the light of the previous findings. In particular the diffuse sound field buildup will be analyzed in detail. Implications for the auditory source width and listener envelopment will be discussed.

  3. 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.

  4. The Effect of Asymmetrical Signal Degradation on Binaural Speech Recognition in Children and Adults.

    ERIC Educational Resources Information Center

    Rothpletz, Ann M.; Tharpe, Anne Marie; Grantham, D. Wesley

    2004-01-01

    To determine the effect of asymmetrical signal degradation on binaural speech recognition, 28 children and 14 adults were administered a sentence recognition task amidst multitalker babble. There were 3 listening conditions: (a) monaural, with mild degradation in 1 ear; (b) binaural, with mild degradation in both ears (symmetric degradation); and…

  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. Binaural Sound Localizer for Azimuthal Movement Detection Based on Diffraction

    PubMed Central

    Kim, Keonwook; Choi, Anthony

    2012-01-01

    Sound localization can be realized by utilizing the physics of acoustics in various methods. This paper investigates a novel detection architecture for the azimuthal movement of sound source based on the interaural level difference (ILD) between two receivers. One of the microphones in the system is surrounded by barriers of various heights in order to cast the direction dependent diffraction of the incoming signal. The gradient analysis of the ILD between the structured and unstructured microphone demonstrates the rotation directions as clockwise, counter clockwise, and no rotation of the sound source. Acoustic experiments with different types of sound source over a wide range of target movements show that the average true positive and false positive rates are 67% and 16%, respectively. Spectral analysis demonstrates that the low frequency delivers decreased true and false positive rates and the high frequency presents increases of both rates, overall. PMID:23112617

  8. 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

  9. 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…

  10. Benefits to Speech Perception in Noise From the Binaural Integration of Electric and Acoustic Signals in Simulated Unilateral Deafness

    PubMed Central

    Ma, Ning; Morris, Saffron; Kitterick, Pádraig Thomas

    2016-01-01

    Objectives: This study used vocoder simulations with normal-hearing (NH) listeners to (1) measure their ability to integrate speech information from an NH ear and a simulated cochlear implant (CI), and (2) investigate whether binaural integration is disrupted by a mismatch in the delivery of spectral information between the ears arising from a misalignment in the mapping of frequency to place. Design: Eight NH volunteers participated in the study and listened to sentences embedded in background noise via headphones. Stimuli presented to the left ear were unprocessed. Stimuli presented to the right ear (referred to as the CI-simulation ear) were processed using an eight-channel noise vocoder with one of the three processing strategies. An Ideal strategy simulated a frequency-to-place map across all channels that matched the delivery of spectral information between the ears. A Realistic strategy created a misalignment in the mapping of frequency to place in the CI-simulation ear where the size of the mismatch between the ears varied across channels. Finally, a Shifted strategy imposed a similar degree of misalignment in all channels, resulting in consistent mismatch between the ears across frequency. The ability to report key words in sentences was assessed under monaural and binaural listening conditions and at signal to noise ratios (SNRs) established by estimating speech-reception thresholds in each ear alone. The SNRs ensured that the monaural performance of the left ear never exceeded that of the CI-simulation ear. The advantages of binaural integration were calculated by comparing binaural performance with monaural performance using the CI-simulation ear alone. Thus, these advantages reflected the additional use of the experimentally constrained left ear and were not attributable to better-ear listening. Results: Binaural performance was as accurate as, or more accurate than, monaural performance with the CI-simulation ear alone. When both ears supported a

  11. 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

  12. Binaural beat salience

    PubMed Central

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

    2012-01-01

    Previous studies of binaural beats have noted individual variability and response lability, but little attention has been paid to the salience of the binaural beat percept. The purpose of this study was to gauge the strength of the binaural beat percept by matching its salience to that of sinusoidal amplitude modulation (SAM), and to then compare rate discrimination for the two types of fluctuation. Rate discrimination was measured for standard rates of 4, 8, 16, and 32 Hz – all in the 500-Hz carrier region. Twelve normal-hearing adults participated in this study. The results indicated that discrimination acuity for binaural beats is similar to that for SAM tones whose depths of modulation have been adjusted to provide equivalent modulation salience. The matched-salience SAM tones had relatively shallow depths of modulation, suggesting that the perceptual strength of binaural beats is relatively weak, although all listeners perceived them. The Weber fraction for detection of an increase in binaural beat rate is roughly constant across beat rates, at least for rates above 4 Hz, as is rate discrimination for SAM tones. PMID:22326292

  13. 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.

  14. Predicting binaural speech intelligibility using the signal-to-noise ratio in the envelope power spectrum domain.

    PubMed

    Chabot-Leclerc, Alexandre; MacDonald, Ewen N; Dau, Torsten

    2016-07-01

    This study proposes a binaural extension to the multi-resolution speech-based envelope power spectrum model (mr-sEPSM) [Jørgensen, Ewert, and Dau (2013). J. Acoust. Soc. Am. 134, 436-446]. It consists of a combination of better-ear (BE) and binaural unmasking processes, implemented as two monaural realizations of the mr-sEPSM combined with a short-term equalization-cancellation process, and uses the signal-to-noise ratio in the envelope domain (SNRenv) as the decision metric. The model requires only two parameters to be fitted per speech material and does not require an explicit frequency weighting. The model was validated against three data sets from the literature, which covered the following effects: the number of maskers, the masker types [speech-shaped noise (SSN), speech-modulated SSN, babble, and reversed speech], the masker(s) azimuths, reverberation on the target and masker, and the interaural time difference of the target and masker. The Pearson correlation coefficient between the simulated speech reception thresholds and the data across all experiments was 0.91. A model version that considered only BE processing performed similarly (correlation coefficient of 0.86) to the complete model, suggesting that BE processing could be considered sufficient to predict intelligibility in most realistic conditions. PMID:27475146

  15. 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

  16. 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

  17. 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

  18. A new perspective on binaural integration using response time methodology: super capacity revealed in conditions of binaural masking release.

    PubMed

    Lentz, Jennifer J; He, Yuan; Townsend, James T

    2014-01-01

    This study applied reaction-time based methods to assess the workload capacity of binaural integration by comparing reaction time (RT) distributions for monaural and binaural tone-in-noise detection tasks. In the diotic contexts, an identical tone + noise stimulus was presented to each ear. In the dichotic contexts, an identical noise was presented to each ear, but the tone was presented to one of the ears 180° out of phase with respect to the other ear. Accuracy-based measurements have demonstrated a much lower signal detection threshold for the dichotic vs. the diotic conditions, but accuracy-based techniques do not allow for assessment of system dynamics or resource allocation across time. Further, RTs allow comparisons between these conditions at the same signal-to-noise ratio. Here, we apply a reaction-time based capacity coefficient, which provides an index of workload efficiency and quantifies the resource allocations for single ear vs. two ear presentations. We demonstrate that the release from masking generated by the addition of an identical stimulus to one ear is limited-to-unlimited capacity (efficiency typically less than 1), consistent with less gain than would be expected by probability summation. However, the dichotic presentation leads to a significant increase in workload capacity (increased efficiency)-most specifically at lower signal-to-noise ratios. These experimental results provide further evidence that configural processing plays a critical role in binaural masking release, and that these mechanisms may operate more strongly when the signal stimulus is difficult to detect, albeit still with nearly 100% accuracy. PMID:25202254

  19. A new perspective on binaural integration using response time methodology: super capacity revealed in conditions of binaural masking release

    PubMed Central

    Lentz, Jennifer J.; He, Yuan; Townsend, James T.

    2014-01-01

    This study applied reaction-time based methods to assess the workload capacity of binaural integration by comparing reaction time (RT) distributions for monaural and binaural tone-in-noise detection tasks. In the diotic contexts, an identical tone + noise stimulus was presented to each ear. In the dichotic contexts, an identical noise was presented to each ear, but the tone was presented to one of the ears 180° out of phase with respect to the other ear. Accuracy-based measurements have demonstrated a much lower signal detection threshold for the dichotic vs. the diotic conditions, but accuracy-based techniques do not allow for assessment of system dynamics or resource allocation across time. Further, RTs allow comparisons between these conditions at the same signal-to-noise ratio. Here, we apply a reaction-time based capacity coefficient, which provides an index of workload efficiency and quantifies the resource allocations for single ear vs. two ear presentations. We demonstrate that the release from masking generated by the addition of an identical stimulus to one ear is limited-to-unlimited capacity (efficiency typically less than 1), consistent with less gain than would be expected by probability summation. However, the dichotic presentation leads to a significant increase in workload capacity (increased efficiency)—most specifically at lower signal-to-noise ratios. These experimental results provide further evidence that configural processing plays a critical role in binaural masking release, and that these mechanisms may operate more strongly when the signal stimulus is difficult to detect, albeit still with nearly 100% accuracy. PMID:25202254

  20. Comparison between bilateral cochlear implants and Neurelec Digisonic(®) SP Binaural cochlear implant: speech perception, sound localization and patient self-assessment.

    PubMed

    Bonnard, Damien; Lautissier, Sylvie; Bosset-Audoit, Amélie; Coriat, Géraldine; Beraha, Max; Maunoury, Antoine; Martel, Jacques; Darrouzet, Vincent; Bébéar, Jean-Pierre; Dauman, René

    2013-01-01

    An alternative to bilateral cochlear implantation is offered by the Neurelec Digisonic(®) SP Binaural cochlear implant, which allows stimulation of both cochleae within a single device. The purpose of this prospective study was to compare a group of Neurelec Digisonic(®) SP Binaural implant users (denoted BINAURAL group, n = 7) with a group of bilateral adult cochlear implant users (denoted BILATERAL group, n = 6) in terms of speech perception, sound localization, and self-assessment of health status and hearing disability. Speech perception was assessed using word recognition at 60 dB SPL in quiet and in a 'cocktail party' noise delivered through five loudspeakers in the hemi-sound field facing the patient (signal-to-noise ratio = +10 dB). The sound localization task was to determine the source of a sound stimulus among five speakers positioned between -90° and +90° from midline. Change in health status was assessed using the Glasgow Benefit Inventory and hearing disability was evaluated with the Abbreviated Profile of Hearing Aid Benefit. Speech perception was not statistically different between the two groups, even though there was a trend in favor of the BINAURAL group (mean percent word recognition in the BINAURAL and BILATERAL groups: 70 vs. 56.7% in quiet, 55.7 vs. 43.3% in noise). There was also no significant difference with regard to performance in sound localization and self-assessment of health status and hearing disability. On the basis of the BINAURAL group's performance in hearing tasks involving the detection of interaural differences, implantation with the Neurelec Digisonic(®) SP Binaural implant may be considered to restore effective binaural hearing. Based on these first comparative results, this device seems to provide benefits similar to those of traditional bilateral cochlear implantation, with a new approach to stimulate both auditory nerves. PMID:23548561

  1. 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. PMID:27080647

  2. Spectral and binaural loudness summation for hearing-impaired listeners.

    PubMed

    Oetting, Dirk; Hohmann, Volker; Appell, Jens-E; Kollmeier, Birger; Ewert, Stephan D

    2016-05-01

    Sensorineural hearing loss typically results in a steepened loudness function and a reduced dynamic range from elevated thresholds to uncomfortably loud levels for narrowband and broadband signals. Restoring narrowband loudness perception for hearing-impaired (HI) listeners can lead to overly loud perception of broadband signals and it is unclear how binaural presentation affects loudness perception in this case. Here, loudness perception quantified by categorical loudness scaling for nine normal-hearing (NH) and ten HI listeners was compared for signals with different bandwidth and different spectral shape in monaural and in binaural conditions. For the HI listeners, frequency- and level-dependent amplification was used to match the narrowband monaural loudness functions of the NH listeners. The average loudness functions for NH and HI listeners showed good agreement for monaural broadband signals. However, HI listeners showed substantially greater loudness for binaural broadband signals than NH listeners: on average a 14.1 dB lower level was required to reach "very loud" (range 30.8 to -3.7 dB). Overall, with narrowband loudness compensation, a given binaural loudness for broadband signals above "medium loud" was reached at systematically lower levels for HI than for NH listeners. Such increased binaural loudness summation was not found for loudness categories below "medium loud" or for narrowband signals. Large individual variations in the increased loudness summation were observed and could not be explained by the audiogram or the narrowband loudness functions. PMID:27006003

  3. Binaural unmasking of frequency-following responses in rat amygdala.

    PubMed

    Du, Yi; Huang, Qiang; Wu, Xihong; Galbraith, Gary C; Li, Liang

    2009-03-01

    Survival in natural environments for small animals such as rats often depends on precise neural coding of life-threatening acoustic signals, and binaural unmasking of species-specific pain calls is especially critical. This study investigated how species-specific tail-pain chatter is represented in the rat amygdala, which receives afferents from both auditory thalamus and auditory association cortex, and whether the amygdaloid representation of the chatter can be binaurally unmasked. The results show that chatter with a fundamental frequency (F0) of 2.1 kHz was able to elicit salient phase-locked frequency-following responses (FFRs) in the lateral amygdala nucleus in anesthetized rats. FFRs to the F0 of binaurally presented chatter were sensitive to the interaural time difference (ITD), with the preference of ipsilateral-ear leading, as well as showing features of binaural inhibition. When interaurally correlated masking noises were added and ipsilateral chatter led contralateral chatter, introducing an ITD disparity between the chatter and masker significantly enhanced (unmasked) the FFRs. This binaural unmasking was further enhanced by chemically blocking excitatory glutamate receptors in the auditory association cortex. When the chatter was replaced by a harmonic tone complex with an F0 of 0.7 kHz, both the binaural-inhibition feature and the binaural unmasking were preserved only for the harmonic of 2.1 kHz but not the tone F0. These results suggest that both frequency-dependent ascending binaural modulations and cortical descending modulations of the precise auditory coding of the chatter in the amygdala are critical for processing life-threatening acoustic signals in noisy and even reverberant environments. PMID:19036862

  4. 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. PMID:25568115

  5. The Neural Substrate for Binaural Masking Level Differences in the Auditory Cortex

    PubMed Central

    Gilbert, Heather J.; 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. PMID:25568115

  6. 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.

  7. A probabilistic model for binaural sound localization.

    PubMed

    Willert, Volker; Eggert, Julian; Adamy, Jürgen; Stahl, Raphael; Körner, Edgar

    2006-10-01

    This paper proposes a biologically inspired and technically implemented sound localization system to robustly estimate the position of a sound source in the frontal azimuthal half-plane. For localization, binaural cues are extracted using cochleagrams generated by a cochlear model that serve as input to the system. The basic idea of the model is to separately measure interaural time differences and interaural level differences for a number of frequencies and process these measurements as a whole. This leads to two-dimensional frequency versus time-delay representations of binaural cues, so-called activity maps. A probabilistic evaluation is presented to estimate the position of a sound source over time based on these activity maps. Learned reference maps for different azimuthal positions are integrated into the computation to gain time-dependent discrete conditional probabilities. At every timestep these probabilities are combined over frequencies and binaural cues to estimate the sound source position. In addition, they are propagated over time to improve position estimation. This leads to a system that is able to localize audible signals, for example human speech signals, even in reverberating environments. PMID:17036807

  8. 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

  9. Statistics of Natural Binaural Sounds

    PubMed Central

    Młynarski, Wiktor; Jost, Jürgen

    2014-01-01

    Binaural sound localization is usually considered a discrimination task, where interaural phase (IPD) and level (ILD) disparities at narrowly tuned frequency channels are utilized to identify a position of a sound source. In natural conditions however, binaural circuits are exposed to a stimulation by sound waves originating from multiple, often moving and overlapping sources. Therefore statistics of binaural cues depend on acoustic properties and the spatial configuration of the environment. Distribution of cues encountered naturally and their dependence on physical properties of an auditory scene have not been studied before. In the present work we analyzed statistics of naturally encountered binaural sounds. We performed binaural recordings of three auditory scenes with varying spatial configuration and analyzed empirical cue distributions from each scene. We have found that certain properties such as the spread of IPD distributions as well as an overall shape of ILD distributions do not vary strongly between different auditory scenes. Moreover, we found that ILD distributions vary much weaker across frequency channels and IPDs often attain much higher values, than can be predicted from head filtering properties. In order to understand the complexity of the binaural hearing task in the natural environment, sound waveforms were analyzed by performing Independent Component Analysis (ICA). Properties of learned basis functions indicate that in natural conditions soundwaves in each ear are predominantly generated by independent sources. This implies that the real-world sound localization must rely on mechanisms more complex than a mere cue extraction. PMID:25285658

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

    PubMed Central

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

    2015-01-01

    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 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

  11. Cortical representation of the combination of monaural and binaural unmasking.

    PubMed

    Uppenkamp, Stefan; Uhlig, Christian H; Verhey, Jesko L

    2013-01-01

    The audibility of a target tone is improved by introducing either -amplitude modulations that are coherent across different frequency channels of the masker (comodulation masking release, CMR) or interaural phase differences that are -different for target and masker (binaural masking-level difference, BMLD). Although the two effects are likely to be based on different processing strategies, they both result in improved figure-background decomposition for a target-in-noise situation. In this study, we analyzed the combination of CMR and BMLD for a -target tone in a masker with six 48-Hz-wide noise bands, distributed over a wide frequency range from 216 Hz to 2.78 kHz. Psychoacoustical detection thresholds for the tones in noise were determined for two masker conditions (comodulated or unmodulated bands) and two interaural phase differences of the target tone (0 or 180°). The mean results indicate that the effects of unmasking add independently. The lowest thresholds are found for the dichotic signal embedded in a -modulated masker with an overall threshold difference of about 16 dB compared to the -unmodulated condition with no binaural cues. Based on the psychoacoustic results, a set of 12 signal-masker configurations was selected individually to explore the representation of the audibility of the test tone in brain activation maps by means of auditory functional MR imaging. The comparison of the results for the combination of CMR and BMLD with the results for the separate effects indicates a large overlap of the activated brain regions, where a largely extended area is activated, covering primary auditory cortex and adjacent regions. The result is in agreement with previous fMRI studies on auditory masking, identifying specific regions in the auditory cortex representing a change of the audibility of a target tone in a noise masker, irrespective of the overall sound pressure level of the stimulus. PMID:23716250

  12. 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

  13. 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

  14. 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

  15. Accuracy of pointing a binaural listening array.

    PubMed

    Letowski, T R; Ricard, G L; Kalb, J T; Mermagen, T J; Amrein, K M

    1997-12-01

    We measured the accuracy with which sounds heard over a binaural, end-fire array could be located when the angular separation of the array's two arms was varied. Each individual arm contained nine cardioid electret microphones, the responses of which were combined to produce a unidirectional, band-limited pattern of sensitivity. We assessed the desirable angular separation of these arms by measuring the accuracy with which listeners could point to the source of a target sound presented against high-level background noise. We employed array separations of 30 degrees, 45 degrees, and 60 degrees, and signal-to-noise ratios of +5, -5, and -15 dB. Pointing accuracy was best for a separation of 60 degrees; this performance was indistinguishable from pointing during unaided listening conditions. In addition, the processing of the array was modeled to depict the information that was available for localization. The model indicates that highly directional binaural arrays can be expected to support accurate localization of sources of sound only near the axis of the array. Wider enhanced listening angles may be possible if the forward coverage of the sensor system is made less directional and more similar to that of human listeners. PMID:9473975

  16. Rate-Constrained Beamforming in Binaural Hearing Aids

    NASA Astrophysics Data System (ADS)

    Srinivasan, Sriram; den Brinker, Albertus C.

    2009-12-01

    Recently, hearing aid systems where the left and right ear devices collaborate with one another have received much attention. Apart from supporting natural binaural hearing, such systems hold great potential for improving the intelligibility of speech in the presence of noise through beamforming algorithms. Binaural beamforming for hearing aids requires an exchange of microphone signals between the two devices over a wireless link. This paper studies two problems: which signal to transmit from one ear to the other, and at what bit-rate. The first problem is relevant as modern hearing aids usually contain multiple microphones, and the optimal choice for the signal to be transmitted is not obvious. The second problem is relevant as the capacity of the wireless link is limited by stringent power consumption constraints imposed by the limited battery life of hearing aids.

  17. Loudness enhancement: Monaural, binaural and dichotic

    NASA Technical Reports Server (NTRS)

    Elmasian, R. O.; Galambos, R.

    1975-01-01

    It is shown that when one tone burst precedes another by 100 msec variations in the intensity of the first systematically influences the loudness of second. When the first burst is more intense than the second, the second is increased and when the first burst is less intense, the loudness of the second is decreased. This occurs in monaural, binaural and dichotic paradigms of signal presentation. Where both bursts are presented to the same ear there is more enhancement with less intersubject variability than when they are presented to different ears. 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.

  18. 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.

  19. Noncoherent detection of periodic signals

    NASA Technical Reports Server (NTRS)

    Gagliardi, R. M.

    1974-01-01

    The optimal Bayes detector for a general periodic waveform having uniform delay and additive white Gaussian noise is examined. It is shown that the detector is much more complex than that for the well known cases of pure sine waves (i.e. classical noncoherent detection) and narrowband signals. An interpretation of the optimal processing is presented, and several implementations are discussed. The results have application to the noncoherent detection of optical square waves.

  20. 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

  1. 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

  2. Binaural Loudness Summation in the Hearing Impaired.

    ERIC Educational Resources Information Center

    Hawkins, David B.; And Others

    1987-01-01

    Binaural loudness summation was measured using three different paradigms with 10 normally hearing and 20 bilaterally symmetrical high-frequency sensorineural hearing loss subjects. Binaural summation increased with presentation level using the loudness matching procedure, with values in the 6-10 dB range. Summation decreased with level using the…

  3. A high-density EEG investigation into steady state binaural beat stimulation.

    PubMed

    Goodin, Peter; Ciorciari, Joseph; Baker, Kate; Carey, Anne-Marie; Carrey, Anne-Marie; Harper, Michelle; Kaufman, Jordy

    2012-01-01

    Binaural beats are an auditory phenomenon that has been suggested to alter physiological and cognitive processes including vigilance and brainwave entrainment. Some personality traits measured by the NEO Five Factor Model have been found to alter entrainment using pulsing light stimuli, but as yet no studies have examined if this occurs using steady state presentation of binaural beats for a relatively short presentation of two minutes. This study aimed to examine if binaural beat stimulation altered vigilance or cortical frequencies and if personality traits were involved. Thirty-one participants were played binaural beat stimuli designed to elicit a response at either the Theta (7 Hz) or Beta (16 Hz) frequency bands while undertaking a zero-back vigilance task. EEG was recorded from a high-density electrode cap. No significant differences were found in vigilance or cortical frequency power during binaural beat stimulation compared to a white noise control period. Furthermore, no significant relationships were detected between the above and the Big Five personality traits. This suggests a short presentation of steady state binaural beats are not sufficient to alter vigilance or entrain cortical frequencies at the two bands examined and that certain personality traits were not more susceptible than others. PMID:22496862

  4. A High-Density EEG Investigation into Steady State Binaural Beat Stimulation

    PubMed Central

    Goodin, Peter; Ciorciari, Joseph; Baker, Kate; Carrey, Anne-Marie; Harper, Michelle; Kaufman, Jordy

    2012-01-01

    Binaural beats are an auditory phenomenon that has been suggested to alter physiological and cognitive processes including vigilance and brainwave entrainment. Some personality traits measured by the NEO Five Factor Model have been found to alter entrainment using pulsing light stimuli, but as yet no studies have examined if this occurs using steady state presentation of binaural beats for a relatively short presentation of two minutes. This study aimed to examine if binaural beat stimulation altered vigilance or cortical frequencies and if personality traits were involved. Thirty-one participants were played binaural beat stimuli designed to elicit a response at either the Theta (7 Hz) or Beta (16 Hz) frequency bands while undertaking a zero-back vigilance task. EEG was recorded from a high-density electrode cap. No significant differences were found in vigilance or cortical frequency power during binaural beat stimulation compared to a white noise control period. Furthermore, no significant relationships were detected between the above and the Big Five personality traits. This suggests a short presentation of steady state binaural beats are not sufficient to alter vigilance or entrain cortical frequencies at the two bands examined and that certain personality traits were not more susceptible than others. PMID:22496862

  5. Binaural Benefit with and without a Bilateral Spectral Mismatch in Acoustic Simulations of Cochlear Implant Processing

    PubMed Central

    Yoon, Yang-soo; Shin, You-Ree; Fu, Qian-Jie

    2012-01-01

    Objectives This study investigated whether a spectral mismatch across ears influences the benefit of redundancy, squelch, and head shadow differently in speech perception using acoustic simulation of bilateral cochlear implant (CI) processing. Design Ten normal hearing subjects participated in the study, and acoustic simulations of CIs were used to test these subjects. Sentence recognition, presented unilaterally and bilaterally, was measured at +5 dB and +10 dB signal-to-noise ratios (SNRs) with bilaterally matched and mismatched conditions. Unilateral and bilateral CIs were simulated using 8-channel sine-wave vocoders. Binaural spectral mismatch was introduced by changing the relative simulated insertion depths across ears. Subjects were tested while listening with headphones; head-related transfer functions were applied before the vocoder processing to preserve natural interaural level and time differences. Results For both SNRs, greater and more consistent binaural benefit of squelch and redundancy occurred for the matched condition while binaural interference of squelch and redundancy occurred for the mismatched condition. However, significant binaural benefit of head shadow existed irrespective of spectral mismatches and SNRs. Conclusions The results suggest that bilateral spectral mismatch may have a negative impact on the binaural benefit of squelch and redundancy for bilateral CI users. The results also suggest that clinical mapping should be carefully administrated for bilateral CI users to minimize the difference in spectral patterns between the two CIs. PMID:22968427

  6. The impact of binaural beats on creativity

    PubMed Central

    Reedijk, Susan A.; Bolders, Anne; Hommel, Bernhard

    2013-01-01

    Human creativity relies on a multitude of cognitive processes, some of which are influenced by the neurotransmitter dopamine. This suggests that creativity could be enhanced by interventions that either modulate the production or transmission of dopamine directly, or affect dopamine-driven processes. In the current study we hypothesized that creativity can be influenced by means of binaural beats, an auditory illusion that is considered a form of cognitive entrainment that operates through stimulating neuronal phase locking. We aimed to investigate whether binaural beats affect creative performance at all, whether they affect divergent thinking, convergent thinking, or both, and whether possible effects may be mediated by the individual striatal dopamine level. Binaural beats were presented at alpha and gamma frequency. Participants completed a divergent and a convergent thinking task to assess two important functions of creativity, and filled out the Positive And Negative Affect Scale—mood State questionnaire (PANAS-S) and an affect grid to measure current mood. Dopamine levels in the striatum were estimated using spontaneous eye blink rates (EBRs). Results showed that binaural beats, regardless of the presented frequency, can affect divergent but not convergent thinking. Individuals with low EBRs mostly benefitted from alpha binaural beat stimulation, while individuals with high EBRs were unaffected or even impaired by both alpha and gamma binaural beats. This suggests that binaural beats, and possibly other forms of cognitive entrainment, are not suited for a one-size-fits-all approach, and that individual cognitive-control systems need to be taken into account when studying cognitive enhancement methods. PMID:24294202

  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. Extracting binaural information from simultaneous targets and distractors: Effects of amplitude modulation and asynchronous envelopes

    PubMed Central

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

    2010-01-01

    When different components of a stimulus carry different binaural information, processing of binaural information in a target component is often affected. The present experiments examine whether such interference is affected by amplitude modulation and the relative phase of modulation of the target and distractors. In all experiments, listeners attempted to discriminate interaural time differences of a target stimulus in the presence of distractor stimuli with ITD=0. In Experiment 1, modulation of the distractors but not the target reduced interference between components. In Experiment 2, synthesized musical notes exhibited little binaural interference when there were slight asynchronies between different streams of notes (31 or 62 ms). The remaining experiments suggested that the reduction in binaural interference in the previous experiments was due neither to the complex spectra of the synthesized notes nor to greater detectability of the target in the presence of modulated distractors. These data suggest that this interference is reduced when components are modulated in ways that result in the target appearing briefly in isolation, not because of segregation cues. These data also suggest that modulation and asynchronies between modulators that might be encountered in real-world listening situations are adequate to reduce binaural interference to inconsequential levels. PMID:20815459

  9. The binaural masking level difference: cortical correlates persist despite severe brain stem atrophy in progressive supranuclear palsy

    PubMed Central

    Rowe, James B.; Ghosh, Boyd C. P.; Carlyon, Robert P.; Plack, Christopher J.; Gockel, Hedwig E.

    2014-01-01

    Under binaural listening conditions, the detection of target signals within background masking noise is substantially improved when the interaural phase of the target differs from that of the masker. Neural correlates of this binaural masking level difference (BMLD) have been observed in the inferior colliculus and temporal cortex, but it is not known whether degeneration of the inferior colliculus would result in a reduction of the BMLD in humans. We used magnetoencephalography to examine the BMLD in 13 healthy adults and 13 patients with progressive supranuclear palsy (PSP). PSP is associated with severe atrophy of the upper brain stem, including the inferior colliculus, confirmed by voxel-based morphometry of structural MRI. Stimuli comprised in-phase sinusoidal tones presented to both ears at three levels (high, medium, and low) masked by in-phase noise, which rendered the low-level tone inaudible. Critically, the BMLD was measured using a low-level tone presented in opposite phase across ears, making it audible against the noise. The cortical waveforms from bilateral auditory sources revealed significantly larger N1m peaks for the out-of-phase low-level tone compared with the in-phase low-level tone, for both groups, indicating preservation of early cortical correlates of the BMLD in PSP. In PSP a significant delay was observed in the onset of the N1m deflection and the amplitude of the P2m was reduced, but these differences were not restricted to the BMLD condition. The results demonstrate that although PSP causes subtle auditory deficits, binaural processing can survive the presence of significant damage to the upper brain stem. PMID:25231610

  10. Transionospheric signal detection with chirped wavelets

    SciTech Connect

    Doser, A.B.; Dunham, M.E.

    1997-11-01

    Chirped wavelets are utilized to detect dispersed signals in the joint time scale domain. Specifically, pulses that become dispersed by transmission through the ionosphere and are received by satellites as nonlinear chirps are investigated. Since the dispersion greatly lowers the signal to noise ratios, it is difficult to isolate the signals in the time domain. Satellite data are examined with discrete wavelet expansions. Detection is accomplished via a template matching threshold scheme. Quantitative experimental results demonstrate that the chirped wavelet detection scheme is successful in detecting the transionospheric pulses at very low signal to noise ratios.

  11. Binaural Fusion and Listening Effort in Children Who Use Bilateral Cochlear Implants: A Psychoacoustic and Pupillometric Study

    PubMed Central

    Steel, Morrison M.; Papsin, Blake C.; Gordon, Karen A.

    2015-01-01

    Bilateral cochlear implants aim to provide hearing to both ears for children who are deaf and promote binaural/spatial hearing. Benefits are limited by mismatched devices and unilaterally-driven development which could compromise the normal integration of left and right ear input. We thus asked whether children hear a fused image (ie. 1 vs 2 sounds) from their bilateral implants and if this “binaural fusion” reduces listening effort. Binaural fusion was assessed by asking 25 deaf children with cochlear implants and 24 peers with normal hearing whether they heard one or two sounds when listening to bilaterally presented acoustic click-trains/electric pulses (250 Hz trains of 36 ms presented at 1 Hz). Reaction times and pupillary changes were recorded simultaneously to measure listening effort. Bilaterally implanted children heard one image of bilateral input less frequently than normal hearing peers, particularly when intensity levels on each side were balanced. Binaural fusion declined as brainstem asymmetries increased and age at implantation decreased. Children implanted later had access to acoustic input prior to implantation due to progressive deterioration of hearing. Increases in both pupil diameter and reaction time occurred as perception of binaural fusion decreased. Results indicate that, without binaural level cues, children have difficulty fusing input from their bilateral implants to perceive one sound which costs them increased listening effort. Brainstem asymmetries exacerbate this issue. By contrast, later implantation, reflecting longer access to bilateral acoustic hearing, may have supported development of auditory pathways underlying binaural fusion. Improved integration of bilateral cochlear implant signals for children is required to improve their binaural hearing. PMID:25668423

  12. Electrophysiological and psychophysical asymmetries in sensitivity to interaural correlation gaps and implications for binaural integration time.

    PubMed

    Lüddemann, Helge; Kollmeier, Birger; Riedel, Helmut

    2016-02-01

    Brief deviations of interaural correlation (IAC) can provide valuable cues for detection, segregation and localization of acoustic signals. This study investigated the processing of such "binaural gaps" in continuously running noise (100-2000 Hz), in comparison to silent "monaural gaps", by measuring late auditory evoked potentials (LAEPs) and perceptual thresholds with novel, iteratively optimized stimuli. Mean perceptual binaural gap duration thresholds exhibited a major asymmetry: they were substantially shorter for uncorrelated gaps in correlated and anticorrelated reference noise (1.75 ms and 4.1 ms) than for correlated and anticorrelated gaps in uncorrelated reference noise (26.5 ms and 39.0 ms). The thresholds also showed a minor asymmetry: they were shorter in the positive than in the negative IAC range. The mean behavioral threshold for monaural gaps was 5.5 ms. For all five gap types, the amplitude of LAEP components N1 and P2 increased linearly with the logarithm of gap duration. While perceptual and electrophysiological thresholds matched for monaural gaps, LAEP thresholds were about twice as long as perceptual thresholds for uncorrelated gaps, but half as long for correlated and anticorrelated gaps. Nevertheless, LAEP thresholds showed the same asymmetries as perceptual thresholds. For gap durations below 30 ms, LAEPs were dominated by the processing of the leading edge of a gap. For longer gap durations, in contrast, both the leading and the lagging edge of a gap contributed to the evoked response. Formulae for the equivalent rectangular duration (ERD) of the binaural system's temporal window were derived for three common window shapes. The psychophysical ERD was 68 ms for diotic and about 40 ms for anti- and uncorrelated noise. After a nonlinear Z-transform of the stimulus IAC prior to temporal integration, ERDs were about 10 ms for reference correlations of ±1 and 80 ms for uncorrelated reference. Hence, a physiologically motivated

  13. 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

  14. Optimal source distribution for binaural synthesis over loudspeakers

    NASA Astrophysics Data System (ADS)

    Takeuchi, Takashi; Nelson, Philip A.

    2002-12-01

    When binaural sound signals are presented with loudspeakers, the system inversion involved gives rise to a number of problems such as a loss of dynamic range and a lack of robustness to small errors and room reflections. The amplification required by the system inversion results in loss of dynamic range. The control performance of such a system deteriorates severely due to small errors resulting from, e.g., misalignment of the system and individual differences in the head related transfer functions at certain frequencies. The required large sound radiation results in severe reflection which also reduces the control performance. A method of overcoming these fundamental problems is proposed in this paper. A conceptual monopole transducer is introduced whose position varies continuously as frequency varies. This gives a minimum processing requirement of the binaural signals for the control to be achieved and all the above problems either disappear or are minimized. The inverse filters have flat amplitude response and the reproduced sound is not colored even outside the relatively large ``sweet area.'' A number of practical solutions are suggested for the realization of such optimally distributed transducers. One of them is a discretization that enables the use of conventional transducer units.

  15. A Comparison of Two Objective Measures of Binaural Processing: The Interaural Phase Modulation Following Response and the Binaural Interaction Component.

    PubMed

    Haywood, Nicholas R; 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

  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. Binaural cues provide for a release from informational masking.

    PubMed

    Tolnai, Sandra; Dolležal, Lena-Vanessa; Klump, Georg M

    2015-10-01

    Informational masking (IM) describes the insensitivity of detecting a change in sound features in a complex acoustical environment when such a change could easily be detected in the absence of distracting sounds. IM occurs because of the similarity between deviant sound and distracting sounds (so-called similarity-based IM) and/or stimulus uncertainty stemming from trial-to-trial variability (so-called uncertainty-based IM). IM can be abolished if similarity-based or uncertainty-based IM are minimized. Here, we modulated similarity-based IM using binaural cues. Standard/deviant tones and distracting tones were presented sequentially, and level-increment thresholds were measured. Deviant tones differed from standard tones by a higher sound level. Distracting tones covered a wide range of levels. Standard/deviant tones and distracting tones were characterized by their interaural time difference (ITD), interaural level difference (ILD), or both ITD and ILD. The larger the ITD or ILD was, the better similarity-based IM was overcome. If both interaural differences were applied to standard/deviant tones, the release from IM was larger than when either interaural difference was used. The results show that binaural cues are potent cues to abolish similarity-based IM and that the auditory system makes use of multiple available cues. PMID:26413722

  18. 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

  19. Density dependence of signal detection in radiographs.

    PubMed

    Burgess, A E; Humphrey, K

    1981-01-01

    We report results of the variation of signal detectability with radiographic film density for Lanex screens and four different x-ray films. We found that maximum signal detectability occurs near (but not precisely at) the maximum slope of the characteristic curve. We interpret our results using a model that includes film gamma quantum noise, film granularity, and an intrinsic observer contrast threshold. PMID:7290017

  20. Human cortical responses to slow and fast binaural beats reveal multiple mechanisms of binaural hearing.

    PubMed

    Ross, Bernhard; Miyazaki, Takahiro; Thompson, Jessica; Jamali, Shahab; Fujioka, Takako

    2014-10-15

    When two tones with slightly different frequencies are presented to both ears, they interact in the central auditory system and induce the sensation of a beating sound. At low difference frequencies, we perceive a single sound, which is moving across the head between the left and right ears. The percept changes to loudness fluctuation, roughness, and pitch with increasing beat rate. To examine the neural representations underlying these different perceptions, we recorded neuromagnetic cortical responses while participants listened to binaural beats at a continuously varying rate between 3 Hz and 60 Hz. Binaural beat responses were analyzed as neuromagnetic oscillations following the trajectory of the stimulus rate. Responses were largest in the 40-Hz gamma range and at low frequencies. Binaural beat responses at 3 Hz showed opposite polarity in the left and right auditory cortices. We suggest that this difference in polarity reflects the opponent neural population code for representing sound location. Binaural beats at any rate induced gamma oscillations. However, the responses were largest at 40-Hz stimulation. We propose that the neuromagnetic gamma oscillations reflect postsynaptic modulation that allows for precise timing of cortical neural firing. Systematic phase differences between bilateral responses suggest that separate sound representations of a sound object exist in the left and right auditory cortices. We conclude that binaural processing at the cortical level occurs with the same temporal acuity as monaural processing whereas the identification of sound location requires further interpretation and is limited by the rate of object representations. PMID:25008412

  1. 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.

  2. 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.

  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. 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.

  5. 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.

  6. VLSI processors for signal detection in SETI

    NASA Astrophysics Data System (ADS)

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

    The objective of the Search for Extraterrestrial Intelligence (SETI) is to locate an artifically 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 incoporate many innovative circuits and architectural features.

  7. VLSI processors for signal detection in SETI.

    PubMed

    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. PMID:11537749

  8. 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.

  9. Analysis of EEG activity in response to binaural beats with different frequencies.

    PubMed

    Gao, Xiang; Cao, Hongbao; Ming, Dong; Qi, Hongzhi; Wang, Xuemin; Wang, Xiaolu; Chen, Runge; Zhou, Peng

    2014-12-01

    When two coherent sounds with nearly similar frequencies are presented to each ear respectively with stereo headphones, the brain integrates the two signals and produces a sensation of a third sound called binaural beat (BB). Although earlier studies showed that BB could influence behavior and cognition, common agreement on the mechanism of BB has not been reached yet. In this work, we employed Relative Power (RP), Phase Locking Value (PLV) and Cross-Mutual Information (CMI) to track EEG changes during BB stimulations. EEG signals were acquired from 13 healthy subjects. Five-minute BBs with four different frequencies were tested: delta band (1 Hz), theta band (5 Hz), alpha band (10 Hz) and beta band (20 Hz). We observed RP increase in theta and alpha bands and decrease in beta band during delta and alpha BB stimulations. RP decreased in beta band during theta BB, while RP decreased in theta band during beta BB. However, no clear brainwave entrainment effect was identified. Connectivity changes were detected following the variation of RP during BB stimulations. Our observation supports the hypothesis that BBs could affect functional brain connectivity, suggesting that the mechanism of BB-brain interaction is worth further study. PMID:25448376

  10. Binaural Advantage for Younger and Older Adults with Normal Hearing

    ERIC Educational Resources Information Center

    Dubno, Judy R.; Ahlstrom, Jayne B.; Horwitz, Amy R.

    2008-01-01

    Purpose: Three experiments measured benefit of spatial separation, benefit of binaural listening, and masking-level differences (MLDs) to assess age-related differences in binaural advantage. Method: Participants were younger and older adults with normal hearing through 4.0 kHz. Experiment 1 compared spatial benefit with and without head shadow.…

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

    PubMed

    Tillein, Jochen; Hubka, Peter; Kral, Andrej

    2016-04-01

    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

  12. 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

  13. 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.

  14. “UTILIZING” SIGNAL DETECTION THEORY

    PubMed Central

    Lynn, Spencer K.; Barrett, Lisa Feldman

    2014-01-01

    What do inferring what a person is thinking or feeling, deciding to report a symptom to your doctor, judging a defendant’s guilt, and navigating a dimly lit room have in common? They involve perceptual uncertainty (e.g., a scowling face might indicate anger or concentration, which engender different appropriate responses), and behavioral risk (e.g., a cost to making the wrong response). Signal detection theory describes these types of decisions. In this tutorial we show how, by incorporating the economic concept of utility, signal detection theory serves as a model of optimal decision making, beyond its common use as an analytic method. This utility approach to signal detection theory highlights potentially enigmatic influences of perceptual uncertainty on measures of decision-making performance (accuracy and optimality) and on behavior (a functional relationship between bias and sensitivity). A “utilized” signal detection theory offers the possibility of expanding the phenomena that can be understood within a decision-making framework. PMID:25097061

  15. 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.

  16. 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.

  17. Chaotic system detection of weak seismic signals

    NASA Astrophysics Data System (ADS)

    Li, Y.; Yang, B. J.; Badal, J.; Zhao, X. P.; Lin, H. B.; Li, R. L.

    2009-09-01

    When the signal-to-noise (S/N) ratio is less than -3 dB or even 0 dB, seismic events are generally difficult to identify from a common shot record. To overcome this type of problem we present a method to detect weak seismic signals based on the oscillations described by a chaotic dynamic system in phase space. The basic idea is that a non-linear chaotic oscillator is strongly immune to noise. Such a dynamic system is less influenced by noise, but it is more sensitive to periodic signals, changing from a chaotic state to a large-scale periodic phase state when excited by a weak signal. With the purpose of checking the possible contamination of the signal by noise, we have performed a numerical experiment with an oscillator controlled by the Duffing-Holmes equation, taking a distorted Ricker wavelet sequence as input signal. In doing so, we prove that the oscillator system is able to reach a large-scale periodic phase state in a strong noise environment. In the case of a common shot record with low S/N ratio, the onsets reflected from a same interface are similar to one other and can be put on a single trace with a common reference time and the periodicity of the so-generated signal follows as a consequence of moveout at a particular scanning velocity. This operation, which is called `horizontal dynamic correction' and leads to a nearly periodic signal, is implemented on synthetic wavelet sequences taking various sampling arrival times and scanning velocities. Thereafter, two tests, both in a noisy ambient of -3.7 dB, are done using a chaotic oscillator: the first demonstrates the capability of the method to really detect a weak seismic signal; the second takes care of the fundamental weakness of the dynamic correction coming from the use of a particular scanning velocity, which is investigated from the effect caused by near-surface lateral velocity variation on the periodicity of the reconstructed seismic signal. Finally, we have developed an application of the

  18. [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

  19. 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.

  20. Optimal signal recovery for pulsed balanced detection

    NASA Astrophysics Data System (ADS)

    de Icaza Astiz, Yannick A.; Lucivero, Vito Giovanni; León-Montiel, R. de J.; Mitchell, Morgan W.

    2014-09-01

    We demonstrate a tool for filtering technical and electronic noises from pulses of light, especially relevant for signal processing methods in quantum optics experiments as a means to achieve the shot-noise level and reduce strong technical noise by means of a pattern function. We provide the theory of this pattern-function filtering based on balance detection. Moreover, we implement an experimental demonstration where 10 dB of technical noise is filtered after balance detection. Such filter can readily be used for probing magnetic atomic ensembles in environments with strong technical noise.

  1. Detection of Smad Signaling in Zebrafish Embryos.

    PubMed

    Liu, Xingfeng; Wang, Qiang; Meng, Anming

    2016-01-01

    Nodal and BMPs play critical roles in germ layer induction and patterning in early zebrafish embryos. Smad2/3 and Smad1/5/8 are intracellular effectors of Nodal and BMPs, respectively. These Smads regulate, in cooperation with other factors, transcription of hundreds of target genes in the nucleus. The activity and stability of Smads are regulated by phosphorylation modifications. To better understand the regulatory network of Smads-mediated signaling and its biological implications, it is necessary to monitor the signaling activity in an in vivo model system. In this chapter, we describe the methods used in zebrafish embryos for dissecting Smads signaling, including TGF-β/Nodal- and BMP-responsive luciferase reporter assays, Western blotting for Smads, co-immunoprecipitation for Smads and their interacting proteins, chromatin-immunoprecipitation for identification of Smad2-binding sites, and immunostaining for detection of active Smad1/5/8. PMID:26520131

  2. 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.

  3. Automated Detection and Location of Indications in Eddy Current Signals

    SciTech Connect

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

    1998-06-30

    A computer implemented information extraction process that locates and identifies eddy current signal features in digital point-ordered signals, said 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. 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

  5. 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

  6. 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.

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

    NASA Technical Reports Server (NTRS)

    Johnson, Marty E.; Lalime, Aimee L.; Grosveld, Ferdinand W.; Rizzi, Stephen A.; Sullivan, Brenda M.

    2003-01-01

    Applying binaural simulation techniques to structural acoustic data can be very computationally intensive as the number of discrete noise sources can be very large. Typically, Head Related Transfer Functions (HRTFs) are used to individually filter the signals from each of the sources in the acoustic field. Therefore, creating a binaural simulation implies the use of potentially hundreds of real time filters. This paper details two methods of reducing the number of real-time computations required by: (i) using the singular value decomposition (SVD) to reduce the complexity of the HRTFs by breaking them into dominant singular values and vectors and (ii) by using equivalent source reduction (ESR) to reduce the number of sources to be analyzed in real-time by replacing sources on the scale of a structural wavelength with sources on the scale of an acoustic wavelength. The ESR and SVD reduction methods can be combined to provide an estimated computation time reduction of 99.4% for the structural acoustic data tested. In addition, preliminary tests have shown that there is a 97% correlation between the results of the combined reduction methods and the results found with the current binaural simulation techniques

  8. 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

  9. 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.

  10. 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

  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. Detecting the cosmological recombination signal from space

    NASA Astrophysics Data System (ADS)

    Desjacques, Vincent; Chluba, Jens; Silk, Joseph; de Bernardis, Francesco; Doré, Olivier

    2015-08-01

    Spectral distortions of the cosmic microwave background (CMB) have recently experienced an increased interest. One of the inevitable distortion signals of our cosmological concordance model is created by the cosmological recombination process, just a little before photons last scatter at redshift z ≃ 1100. These cosmological recombination lines, emitted by the hydrogen and helium plasma, should still be observable as tiny deviation from the CMB blackbody spectrum in the cm-dm spectral bands. In this paper, we present a forecast for the detectability of the recombination signal with future satellite experiments. We argue that serious consideration for future CMB experiments in space should be given to probing spectral distortions and, in particular, the recombination line signals. The cosmological recombination radiation not only allows determination of standard cosmological parameters, but also provides a direct observational confirmation for one of the key ingredients of our cosmological model: the cosmological recombination history. We show that, with present technology, such experiments are futuristic but feasible. The potential rewards won by opening this new window to the very early universe could be considerable.

  13. The pattern of Fos expression in the rat auditory brainstem changes with the temporal structure of binaural electrical intracochlear stimulation.

    PubMed

    Jakob, Till F; Döring, Ulrike; Illing, Robert-Benjamin

    2015-04-01

    The immediate-early-gene c-fos with its protein product Fos has been used as a powerful tool to investigate neuronal activity and plasticity following sensory stimulation. Fos combines with Jun, another IEG product, to form the dimeric transcription factor activator protein 1 (AP-1) which has been implied in a variety of cellular functions like neuronal plasticity, apoptosis, and regeneration. The intracellular emergence of Fos indicates a functional state of nerve cells directed towards molecular and morphological changes. The central auditory system is construed to detect stimulus intensity, spectral composition, and binaural balance through neurons organized in a complex network of ascending, descending and commissural pathways. Here we compare monaural and binaural electrical intracochlear stimulation (EIS) in normal hearing and early postnatally deafened rats. Binaural stimulation was done either synchronously or asynchronously. The auditory brainstem of hearing and deaf rats responds differently, with a dramatically increasing Fos expression in the deaf group so as if the network had no pre-orientation for how to organize sensory activity. Binaural EIS does not result in a trivial sum of 2 independent monaural EIS, as asynchronous stimulation invokes stronger Fos activation compared to synchronous stimulation almost everywhere in the auditory brainstem. The differential response to synchronicity of the stimulation puts emphasis on the importance of the temporal structure of EIS with respect to its potential for changing brain structure and brain function in stimulus-specific ways. PMID:25708983

  14. 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

  15. 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

  16. Availability of binaural cues for bilateral implant recipients and bimodal listeners with and without preserved hearing in the implanted ear

    PubMed Central

    Dorman, Michael F.; Sheffield, Sterling W.; Teece, Kate; Olund, Amy P.; Gifford, René H.

    2014-01-01

    The purpose of the current study was to examine the availability of binaural cues for adult, bilateral cochlear implant (CI) patients, bimodal patients and hearing preservation patients using a multiple baseline, observational study design. Speech recognition was assessed using the Bamford-Kowal-Bench Speech-In-Noise (BKB-SIN) test as well as the AzBio sentences [Spahr et al., 2012] presented in a multi-talker babble at +5 dB signal-to-noise ratio (SNR). Test conditions included speech at 0° with noise presented at 0° (S0N0), 90° (S0N90), and 270° (S0N270). Estimates of summation, head shadow (HS), squelch, and spatial release from masking (SRM) were calculated. Though none of the subject groups consistently showed access to binaural cues, the hearing preservation patients exhibited a significant correlation between summation and squelch whereas the bilateral and bimodal participants did not. That is, the two effects associated with binaural hearing—summation and squelch—were positively correlated for only the listeners with bilateral acoustic hearing. This finding provides evidence for the supposition that implant recipients with bilateral acoustic hearing have access to binaural cues which should, in theory, provide greater benefit in noisy listening environments. It is likely, however, that the chosen test environment negatively affected the outcomes. Specifically, the spatially separated noise conditions directed noise toward the mic port of the behind-the-ear (BTE) hearing aid and implant processor. Thus it is possible that in more realistic listening environments for which the diffuse noise is not directed toward the processor/hearing aid mic, hearing preservation patients have binaural hearing cues for improved speech understanding. PMID:24356514

  17. Dose response signal detection under model uncertainty.

    PubMed

    Dette, Holger; Titoff, Stefanie; Volgushev, Stanislav; Bretz, Frank

    2015-12-01

    We investigate likelihood ratio contrast tests for dose response signal detection under model uncertainty, when several competing regression models are available to describe the dose response relationship. The proposed approach uses the complete structure of the regression models, but does not require knowledge of the parameters of the competing models. Standard likelihood ratio test theory is applicable in linear models as well as in nonlinear regression models with identifiable parameters. However, for many commonly used nonlinear dose response models the regression parameters are not identifiable under the null hypothesis of no dose response and standard arguments cannot be used to obtain critical values. We thus derive the asymptotic distribution of likelihood ratio contrast tests in regression models with a lack of identifiability and use this result to simulate the quantiles based on Gaussian processes. The new method is illustrated with a real data example and compared to existing procedures using theoretical investigations as well as simulations. PMID:26228796

  18. 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.

  19. Binaural interaction in human auditory brainstem response compared for tone-pips and rectangular clicks under conditions of auditory and visual attention.

    PubMed

    Ikeda, Kazunari

    2015-07-01

    Binaural interaction in the auditory brainstem response (ABR) represents the discrepancy between the binaural waveform and the sum of monaural ones. A typical ABR binaural interaction in humans is a reduction of the binaural amplitude compared to the monaural sum at the wave-V latency, i.e., the DN1 component. It has been considered that the DN1 is mainly elicited by high frequency components of stimuli whereas some studies have shown the contribution of low-to-middle frequency components to the DN1. To examine this issue, the present study compared the ABR binaural interaction elicited by tone pips (1 kHz, 10-ms duration) with the one by clicks (a rectangular wave, 0.1-ms duration) presented at 80 dB peak equivalent SPL and a fixed stimulus onset interval (180 ms). The DN1 due to tone pips was vulnerable compared to the click-evoked DN1. The pip-evoked DN1 was significantly detected under auditory attention whereas it failed to reach significance under visual attention. The click-evoked DN1 was robustly present for the two attention conditions. The current results might confirm the high frequency sound contribution to the DN1 elicitation. PMID:25776741

  20. On the detection of differentially encoded polyphase signals.

    NASA Technical Reports Server (NTRS)

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

    1972-01-01

    Consideration of the transmission and detection of differentially encoded multiple phase-shift-keyed (MPSK) signals, paying particular attention to the ambiguity resolution problem resulting from suppression of the transmitted carrier. A study is made of the coherent detection of differentially encoded MPSK signals, and the performance of a differentially encoded MPSK system is compared with that of a system which transmits absolutely encoded polyphase signals and performs perfect ambiguity resolution. Both the perfect and noisy reference signal cases are treated. Also, the performance of coherent detection of differentially encoded MPSK signals is compared with that of differentially coherent reception of the same signal set.

  1. 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.

  2. Binaural hearing in children using Gaussian enveloped and transposed tones.

    PubMed

    Ehlers, Erica; Kan, Alan; Winn, Matthew B; Stoelb, Corey; Litovsky, Ruth Y

    2016-04-01

    Children who use bilateral cochlear implants (BiCIs) show significantly poorer sound localization skills than their normal hearing (NH) peers. This difference has been attributed, in part, to the fact that cochlear implants (CIs) do not faithfully transmit interaural time differences (ITDs) and interaural level differences (ILDs), which are known to be important cues for sound localization. Interestingly, little is known about binaural sensitivity in NH children, in particular, with stimuli that constrain acoustic cues in a manner representative of CI processing. In order to better understand and evaluate binaural hearing in children with BiCIs, the authors first undertook a study on binaural sensitivity in NH children ages 8-10, and in adults. Experiments evaluated sound discrimination and lateralization using ITD and ILD cues, for stimuli with robust envelope cues, but poor representation of temporal fine structure. Stimuli were spondaic words, Gaussian-enveloped tone pulse trains (100 pulse-per-second), and transposed tones. Results showed that discrimination thresholds in children were adult-like (15-389 μs for ITDs and 0.5-6.0 dB for ILDs). However, lateralization based on the same binaural cues showed higher variability than seen in adults. Results are discussed in the context of factors that may be responsible for poor representation of binaural cues in bilaterally implanted children. PMID:27106319

  3. 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.

  4. 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.

  5. 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.

  6. 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

  7. Prediction of the influence of reverberation on binaural speech intelligibility in noise and in quiet.

    PubMed

    Rennies, Jan; Brand, Thomas; Kollmeier, Birger

    2011-11-01

    Reverberation usually degrades speech intelligibility for spatially separated speech and noise sources since spatial unmasking is reduced and late reflections decrease the fidelity of the received speech signal. The latter effect could not satisfactorily be predicted by a recently presented binaural speech intelligibility model [Beutelmann et al. (2010). J. Acoust. Soc. Am. 127, 2479-2497]. This study therefore evaluated three extensions of the model to improve its predictions: (1) an extension of the speech intelligibility index based on modulation transfer functions, (2) a correction factor based on the room acoustical quantity "definition," and (3) a separation of the speech signal into useful and detrimental parts. The predictions were compared to results of two experiments in which speech reception thresholds were measured in a reverberant room in quiet and in the presence of a noise source for listeners with normal hearing. All extensions yielded better predictions than the original model when the influence of reverberation was strong, while predictions were similar for conditions with less reverberation. Although model (3) differed substantially in the assumed interaction of binaural processing and early reflections, its predictions were very similar to model (2) that achieved the best fit to the data. PMID:22087928

  8. Perceptually aligning apical frequency regions leads to more binaural fusion of speech in a cochlear implant simulation.

    PubMed

    Staisloff, Hannah E; Lee, Daniel H; Aronoff, Justin M

    2016-07-01

    For bilateral cochlear implant users, the left and right arrays are typically not physically aligned, resulting in a degradation of binaural fusion, which can be detrimental to binaural abilities. Perceptually aligning the two arrays can be accomplished by disabling electrodes in one ear that do not have a perceptually corresponding electrode in the other side. However, disabling electrodes at the edges of the array will cause compression of the input frequency range into a smaller cochlear extent, which may result in reduced spectral resolution. An alternative approach to overcome this mismatch would be to only align one edge of the array. By aligning either only the apical or basal end of the arrays, fewer electrodes would be disabled, potentially causing less reduction in spectral resolution. The goal of this study was to determine the relative effect of aligning either the basal or apical end of the electrode with regards to binaural fusion. A vocoder was used to simulate cochlear implant listening conditions in normal hearing listeners. Speech signals were vocoded such that the two ears were either predominantly aligned at only the basal or apical end of the simulated arrays. The experiment was then repeated with a spectrally inverted vocoder to determine whether the detrimental effects on fusion were related to the spectral-temporal characteristics of the stimuli or the location in the cochlea where the misalignment occurred. In Experiment 1, aligning the basal portion of the simulated arrays led to significantly less binaural fusion than aligning the apical portions of the simulated array. However, when the input was spectrally inverted, aligning the apical portion of the simulated array led to significantly less binaural fusion than aligning the basal portions of the simulated arrays. These results suggest that, for speech, with its predominantly low frequency spectral-temporal modulations, it is more important to perceptually align the apical portion of

  9. 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.

  10. Signal Detection with Criterion Noise: Applications to Recognition Memory

    ERIC Educational Resources Information Center

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

    2009-01-01

    A tacit but fundamental assumption of the theory of signal detection is that criterion placement is a noise-free process. This article 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…

  11. Signal Detection Models with Random Participant and Item Effects

    ERIC Educational Resources Information Center

    Rouder, Jeffrey N.; Lu, Jun; Sun, Dongchu; Speckman, Paul; Morey, Richard; Naveh-Benjamin, Moshe

    2007-01-01

    The theory of signal detection is convenient for measuring mnemonic ability in recognition memory paradigms. In these paradigms, randomly selected participants are asked to study randomly selected items. In practice, researchers aggregate data across items or participants or both. The signal detection model is nonlinear; consequently, analysis…

  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. Transient signal detection using the empirical mode decomposition

    NASA Astrophysics Data System (ADS)

    Larsen, Michael L.; Ridgway, Jeffrey; Waldman, Cye H.; Gabbay, Michael; Buntzen, Rodney R.; Battista, Brad

    2004-10-01

    In this paper, we report on efforts to develop signal processing methods appropriate for the detection of man-made electromagnetic signals in the nonlinear and nonstationary underwater electromagnetic noise environment of the littoral. Using recent advances in time series analysis methods [Huang et al., 1998], we present new techniques for detection and compare their effectiveness with conventional signal processing methods, using experimental data from recent field experiments. These techniques are based on an empirical mode decomposition which is used to isolate signals to be detected from noise without a priori assumptions. The decomposition generates a physically motivated basis for the data.

  14. 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.

  15. Signal processing in cryogenic particle detection

    NASA Astrophysics Data System (ADS)

    Yuryev, Y. N.; Jang, Y. S.; Kim, S. K.; Lee, K. B.; Lee, M. K.; Lee, S. J.; Yoon, W. S.; Kim, Y. H.

    2011-04-01

    We describe a signal-processing program for a data acquisition system for cryogenic particle detectors. The program is based on an optimal-filtering method for high-resolution measurement of calorimetric signals with a significant amount of noise of unknown origin and non-stationary behavior. The program was applied to improve the energy resolution of the alpha particle spectrum of an 241Am source.

  16. Binaural speech unmasking and localization in noise with bilateral cochlear implants using envelope and fine-timing based strategies.

    PubMed

    van Hoesel, Richard; Böhm, Melanie; Pesch, Jörg; Vandali, Andrew; Battmer, Rolf D; Lenarz, Thomas

    2008-04-01

    Four adult bilateral cochlear implant users, with good open-set sentence recognition, were tested with three different sound coding strategies for binaural speech unmasking and their ability to localize 100 and 500 Hz click trains in noise. Two of the strategies tested were envelope-based strategies that are clinically widely used. The third was a research strategy that additionally preserved fine-timing cues at low frequencies. Speech reception thresholds were determined in diotic noise for diotic and interaurally time-delayed speech using direct audio input to a bilateral research processor. Localization in noise was assessed in the free field. Overall results, for both speech and localization tests, were similar with all three strategies. None provided a binaural speech unmasking advantage due to the application of 700 micros interaural time delay to the speech signal, and localization results showed similar response patterns across strategies that were well accounted for by the use of broadband interaural level cues. The data from both experiments combined indicate that, in contrast to normal hearing, timing cues available from natural head-width delays do not offer binaural advantages with present methods of electrical stimulation, even when fine-timing cues are explicitly coded. PMID:18397030

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

    PubMed Central

    Shackleton, Trevor M.; Magezi, David A.; Palmer, Alan R.

    2014-01-01

    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

  18. 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

  19. 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.

  20. 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.

  1. 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. .

  2. Signal analysis techniques for incipient failure detection in turbomachinery

    NASA Technical Reports Server (NTRS)

    Coffin, T.

    1985-01-01

    Signal analysis techniques for the detection and classification of incipient mechanical failures in turbomachinery were developed, implemented and evaluated. 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 were implemented on a computer and applied to dynamic signals. A laboratory evaluation of the methods with respect to signal detection capability is described. Plans for further technique evaluation and data base development to characterize turbopump incipient failure modes from Space Shuttle main engine (SSME) hot firing measurements are outlined.

  3. 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.

  4. 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.

  5. 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.

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

    PubMed Central

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

    2008-01-01

    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. PMID:18304948

  7. 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.

  8. 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.

  9. 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.

  10. 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. PMID:12374342

  11. 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…

  12. 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.

  13. 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.

  14. 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. PMID:26218060

  15. 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

  16. Smartphone application for emergency signal detection.

    PubMed

    Figueiredo, Isabel N; Leal, Carlos; Pinto, Luís; Bolito, Jason; Lemos, André

    2016-09-01

    Currently, a number of studies focus on the study and design of new healthcare technologies to improve elderly health and quality of life. Taking advantage of the popularity, portability, and inherent technology of smartphones, we present an emergency application for smartphones, designated as knock-to-panic (KTP). This innovative and novel system enables users to simply hit their devices in order to send an alarm signal to an emergency service. This application is a complete and autonomous emergency system, and can provide an economic, reliable, and unobtrusive method for elderly monitoring or safety protection. Moreover, the simple and fast activation of KTP makes it a viable and potentially superior alternative to traditional ambient assisted living emergency calls. Furthermore, KTP can be further extended to the general population as well and not just be limited for elderly persons. The proposed method is a threshold-based algorithm and is designed to require a low battery power consumption. The evaluation of the performance of the algorithm in collected data indicates that both sensitivity and specificity are above 90%. PMID:27264240

  17. 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

  18. 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

  19. 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

  20. 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.

  1. 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

  2. Detection of continuous-time quaternion signals in additive noise

    NASA Astrophysics Data System (ADS)

    Navarro-Moreno, Jesús; Ruiz-Molina, Juan Carlos; Oya, Antonia; Quesada-Rubio, José M.

    2012-12-01

    Different kinds of quaternion signal detection problems in continuous-time by using a widely linear processing are dealt with. The suggested solutions are based on an extension of the Karhunen-Loève expansion to the quaternion domain which provides uncorrelated scalar real-valued random coefficients. This expansion presents the notable advantage of transforming the original four-dimensional eigen problem to a one-dimensional problem. Firstly, we address the problem of detecting a quaternion deterministic signal in quaternion Gaussian noise and a version of Pitcher's Theorem is given. Also the particular case of a general quaternion Wiener noise is studied and an extension of the Cameron-Martin formula is presented. Finally, the problem of detecting a quaternion random signal in quaternion white Gaussian noise is tackled. In such a case, it is shown that the detector depends on the quaternion widely linear estimator of the signal.

  3. 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.

  4. [The design of circuit for detecting multi-physiological signals].

    PubMed

    Liu, Jie; Wang, Bo; Liu, Wen

    2009-12-01

    In this paper is presented the design of detection circuit and single chip acquisition circuit for heart sound, blood pressure and pulse wave. The multi-physiological signals from single chip are synthesized and processed by master computer. The master computer acquires, analyzes and displays the multi-signals by Software LabVIEW. The three physiological signals are fused to calculate the artery stiffness index by time relation of multi-physiological signals. The experiment shows that the circuit is reliable and effective so that it can be used for human vessel function evaluation. PMID:20095475

  5. Embolic Doppler ultrasound signal detection using discrete wavelet transform.

    PubMed

    Aydin, Nizamettin; Marvasti, Farokh; Markus, Hugh S

    2004-06-01

    Asymptomatic circulating emboli can be detected by Doppler ultrasound. Embolic Doppler ultrasound signals are short duration transient like signals. The wavelet transform is an ideal method for analysis and detection of such signals by optimizing time-frequency resolution. We propose a detection system based on the discrete wavelet transform (DWT) and study some parameters, which might be useful for describing embolic signals (ES). We used a fast DWT algorithm based on the Daubechies eighth-order wavelet filters with eight scales. In order to evaluate feasibility of the DWT of ES, two independent data sets, each comprising of short segments containing an ES (N = 100), artifact (N = 100) or Doppler speckle (DS) (N = 100), were used. After applying the DWT to the data, several parameters were evaluated. The threshold values used for both data sets were optimized using the first data set. While the DWT coefficients resulting from artifacts dominantly appear at the higher scales (five, six, seven, and eight), the DWT coefficients at the lower scales (one, two, three, and four) are mainly dominated by ES and DS. The DWT is able to filter out most of the artifacts inherently during the transform process. For the first data set, 98 out of 100 ES were detected as ES. For the second data set, 95 out of 100 ES were detected as ES when the same threshold values were used. The algorithm was also tested with a third data set comprising 202 normal ES; 198 signals were detected as ES. PMID:15217263

  6. Detection of noise-corrupted sinusoidal signals with Josephson junctions

    NASA Astrophysics Data System (ADS)

    Filatrella, Giovanni; Pierro, Vincenzo

    2010-10-01

    We investigate the possibility of exploiting the speed and low noise features of Josephson junctions for detecting sinusoidal signals masked by Gaussian noise. We show that the escape time from the static locked state of a Josephson junction is very sensitive to a small periodic signal embedded in the noise, and therefore the analysis of the escape times can be employed to reveal the presence of the sinusoidal component. We propose and characterize two detection strategies: in the first, the initial phase is supposedly unknown (incoherent strategy), while in the second, the signal phase remains unknown but is fixed (coherent strategy). Our proposals are both suboptimal, with the linear filter being the optimal detection strategy, but they present some remarkable features, such as resonant activation, that make detection through Josephson junctions appealing in some special cases.

  7. 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.

  8. Lateral reflections are favorable in concert halls due to binaural loudness.

    PubMed

    Lokki, Tapio; Pätynen, Jukka

    2011-11-01

    A recent study on perceptual difference in simulated concert halls showed that a concert hall renders stronger sound with more bass when the temporal envelope of a signal is preserved in the reflections [Lokki et al., J. Acoust. Soc. Am. 129, EL223-EL228 (2011)]. In the same study the lateral reflections were shown to contribute to the perceived envelopment and openness. Moreover, the listening test results suggest that lateral reflections contribute to perception of sound source distance. Here, it is shown that lateral reflections are beneficial due to their increasing effect on binaural loudness-the phenomenon known well in psychoacoustics, but not in architectural acoustics. The reflections from the side are amplified more than median plane reflections, in particular at high frequencies, due to the shape of the human head. PMID:22088039

  9. 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

  10. 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.

  11. Statistically robust detection of spontaneous, non-stereotypical neural signals.

    PubMed

    Liu, Fan; Merwine, David K; Grzywacz, Norberto M

    2006-06-15

    Neural signals of interest are often temporally spontaneous and non-stereotypical in waveform. Detecting such signals is difficult, since one cannot use time-locking or simple template-matching techniques. We have sought a statistical method for automatically estimating the baseline in these conditions, and subsequently detecting the occurrence of neural signals. One could consider the signals as outliers in the distribution of neural activity and thus separate them from the baseline with median-based techniques. However, we found that baseline estimators that rely on the median are problematic. They introduce progressively greater estimation errors as the neural signal's duration, amplitude or frequency increases. Therefore, we tested several mode-based algorithms, taking advantage of the most probable state of the neural activity being the baseline. We found that certain mode-based algorithms perform baseline estimation well, with low susceptibility to changes in event duration, amplitude or frequency. Once the baseline is properly established, its median absolute deviation (MAD) can be determined. One can then use it to detect spontaneous signals robustly as outliers from the noise distribution. We also demonstrate how the choice of detection threshold in terms of MADs can be used to bias against false positives, without creating too many false negatives or vice versa. PMID:16430965

  12. Signal detection in post-marketing surveillance for controlled substances.

    PubMed

    Dasgupta, Nabarun; Schnoll, Sidney H

    2009-12-01

    Signal detection for pharmaceutical controlled substances presents unique challenges compared to other pharmacovigilance programs because risks are present in the patient and non-patient populations. Defining signals for controlled substances has been difficult because no specific empirical criteria have been established through regulatory actions or guidances. We start with a review of data sources available for decision making to regulators and industry. In this paper we present a framework for processing signals received during post-marketing surveillance: signal identification, verification and assessment, followed by intervention and evaluation. Signal identification involves processing qualitative and quantitative information in order to generate hypotheses describing concerns with controlled substances. Integration of heterogeneous data sources makes this process difficult and we describe multiple approaches utilized in practice today. Signal verification currently relies heavily on telephone interviews with stakeholders in local communities. Once information on a potential signal has been gathered signal assessment is a higher order process conducted with an eye towards broader societal expectations and the ability to intervene or further study the problem. Intervention and evaluation complete the cycle of signal assessment and triage. This paper is intended as a primer of the current practice of signal assessment in the post-marketing surveillance for controlled substances. PMID:19616902

  13. Coherent Detection of High-Rate Optical PPM Signals

    NASA Technical Reports Server (NTRS)

    Vilnrotter, Victor; Fernandez, Michela Munoz

    2006-01-01

    A method of coherent detection of high-rate pulse-position modulation (PPM) on a received laser beam has been conceived as a means of reducing the deleterious effects of noise and atmospheric turbulence in free-space optical communication using focal-plane detector array technologies. In comparison with a receiver based on direct detection of the intensity modulation of a PPM signal, a receiver based on the present method of coherent detection performs well at much higher background levels. In principle, the coherent-detection receiver can exhibit quantum-limited performance despite atmospheric turbulence. The key components of such a receiver include standard receiver optics, a laser that serves as a local oscillator, a focal-plane array of photodetectors, and a signal-processing and data-acquisition assembly needed to sample the focal-plane fields and reconstruct the pulsed signal prior to detection. The received PPM-modulated laser beam and the local-oscillator beam are focused onto the photodetector array, where they are mixed in the detection process. The two lasers are of the same or nearly the same frequency. If the two lasers are of different frequencies, then the coherent detection process is characterized as heterodyne and, using traditional heterodyne-detection terminology, the difference between the two laser frequencies is denoted the intermediate frequency (IF). If the two laser beams are of the same frequency and remain aligned in phase, then the coherent detection process is characterized as homodyne (essentially, heterodyne detection at zero IF). As a result of the inherent squaring operation of each photodetector, the output current includes an IF component that contains the signal modulation. The amplitude of the IF component is proportional to the product of the local-oscillator signal amplitude and the PPM signal amplitude. Hence, by using a sufficiently strong local-oscillator signal, one can make the PPM-modulated IF signal strong enough to

  14. Respiratory rate detection algorithms by photoplethysmography signal processing.

    PubMed

    Lee, E M; Kim, N H; Trang, N T; Hong, J H; Cha, E J; Lee, T S

    2008-01-01

    Photoplethysmography (PPG) offers the clinically meaningful parameters, such as, heart rate, and respiratory rate. In this study, we presented three respiratory signal detection algorithms using photoplethysmography raw data generated from commercial PPG sensor: (1)Min-Max (2)Peak-to-Peak (3)Pulse Shape. As reference signal, nasal sensor signal was acquired simultaneously and compared and analyzed. We used two types of moving average filtering technique to process three PPG parameters. In laboratory experiment, 6 subjects' PPG signals were measured when they respire ten and fifteen, and arbitrary times per minute. From the results, following conclusions were drawn. Min-Max and Peak-to-Peak algorithms perform better than Pulse shape algorithm. They can be used to detect respiratory rate. But, Pulse Shape algorithm was accurate for subject 4 only. More experimental data is necessary to improve the accuracy and reliability. PMID:19162865

  15. Local Earthquake Detection in Marine Environments Using Seismic Signal Parameters

    NASA Astrophysics Data System (ADS)

    Williams, M. C.; Trehu, A. M.; Braunmiller, J.

    2010-12-01

    The amphibious Central Oregon Locked Zone Array (COLZA) of seismic stations was deployed from 2007-2009 to record earthquakes occurring in the seismogenic zone offshore central Oregon. This array included two year-long deployments of ocean bottom seismometers (OBS's) from the NSF OBSIP. In addition to local and distant earthquakes, the OBS array recorded thousands of impulsive local signals, which are not easily filtered out by a standard STA/LTA detection algorithm. Many of these signals are likely of biological origin (informally referred to as “fish bumps”). These signals have a wide range of amplitudes, can mask local earthquake phase arrivals, and make automatic detection difficult. We show that signal characteristics derived from 3-component seismic data at each station can be used to filter out event detections that are unlikely to be earthquake-generated. A decision-making algorithm, such as an artificial neural network, will be applied to the joint set of signal characteristics to identify possible local events and classify detections that are likely to be "bumps". Detecting low-magnitude local earthquake phases in the high-noise marine environment requires that a standard STA/LTA detector must have a relatively low signal-to-noise ratio (SNR) threshold. Using an SNR threshold of 3 in the 1-5 Hz frequency band detects P-arrivals of local earthquakes of magnitude M = ~1.5, but flags hundreds of impulsive local “bumps” per day for each single OBS. Due to the random nature of the impulsive events, it is impractical to filter them out by comparing to neighboring stations. However, additional a priori information from detected waveforms may provide an effective means for distinguishing earthquakes from other events. For each detection, we determine 3 additional signal characteristics from the 3-component waveform data: the variance of the power cepstrum calculated from a portion of the signal spectrum, the rectilinearity of particle motion, and the

  16. 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.

  17. 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

  18. Study of the fluorescence signal for gastrointestinal dysplasia detection

    NASA Astrophysics Data System (ADS)

    Pimenta, S.; Castanheira, E. M. S.; Minas, G.

    2014-08-01

    The detection of cancer at the dysplasia stage is one of the most important goals in biomedical research. Optical techniques, specifically diffuse reflectance and intrinsic fluorescence, may improve the ability to detect gastrointestinal (GI) cancers, since they have exquisite sensitivity to some intrinsic biomarkers present on the tissues. This work follows the research that has been done towards the implementation of a spectroscopy microsystem for the early detection of GI cancers. For that purpose, the behavior of the fluorescence signal, at different temperatures and considering the most important biomarkers in GI malignancy detection, was studied and presented.

  19. 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.

  20. 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. PMID:26721922

  1. Detection algorithm of big bandwidth chirp signals based on STFT

    NASA Astrophysics Data System (ADS)

    Wang, Jinzhen; Wu, Juhong; Su, Shaoying; Chen, Zengping

    2014-10-01

    Aiming at solving the problem of detecting the wideband chirp signals under low Signal-to-Noise Ratio (SNR) condition, an effective signal detection algorithm based on Short-Time-Fourier-Transform (STFT) is proposed. Considering the characteristic of dispersion of noise spectrum and concentration of chirp spectrum, STFT is performed on chirp signals with Gauss window by fixed step, and these frequencies of peak spectrum obtained from every STFT are in correspondence to the time of every stepped window. Then, the frequencies are binarized and the approach similar to mnk method in time domain is used to detect the chirp pulse signal and determine the coarse starting time and ending time. Finally, the data segments, where the former starting time and ending time locate, are subdivided into many segments evenly, on which the STFT is implemented respectively. By that, the precise starting and ending time are attained. Simulations shows that when the SNR is higher than -28dB, the detection probability is not less than 99% and false alarm probability is zero, and also good estimation accuracy of starting and ending time is acquired. The algorithm is easy to realize and surpasses FFT in computation when the width of STFT window and step length are selected properly, so the presented algorithm has good engineering value.

  2. 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.

  3. 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.

  4. Falling Person Detection Using Multi-Sensor Signal Processing

    NASA Astrophysics Data System (ADS)

    Toreyin, B. Ugur; Soyer, A. Birey; Onaran, Ibrahim; Cetin, E. Enis

    2007-12-01

    Falls are one of the most important problems for frail and elderly people living independently. Early detection of falls is vital to provide a safe and active lifestyle for elderly. Sound, passive infrared (PIR) and vibration sensors can be placed in a supportive home environment to provide information about daily activities of an elderly person. In this paper, signals produced by sound, PIR and vibration sensors are simultaneously analyzed to detect falls. Hidden Markov Models are trained for regular and unusual activities of an elderly person and a pet for each sensor signal. Decisions of HMMs are fused together to reach a final decision.

  5. 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

  6. Role of binaural hearing in speech intelligibility and spatial release from masking using vocoded speech.

    PubMed

    Garadat, Soha N; Litovsky, Ruth Y; Yu, Gongqiang; Zeng, Fan-Gang

    2009-11-01

    A cochlear implant vocoder was used to evaluate relative contributions of spectral and binaural temporal fine-structure cues to speech intelligibility. In Study I, stimuli were vocoded, and then convolved through head related transfer functions (HRTFs) to remove speech temporal fine structure but preserve the binaural temporal fine-structure cues. In Study II, the order of processing was reversed to remove both speech and binaural temporal fine-structure cues. Speech reception thresholds (SRTs) were measured adaptively in quiet, and with interfering speech, for unprocessed and vocoded speech (16, 8, and 4 frequency bands), under binaural or monaural (right-ear) conditions. Under binaural conditions, as the number of bands decreased, SRTs increased. With decreasing number of frequency bands, greater benefit from spatial separation of target and interferer was observed, especially in the 8-band condition. The present results demonstrate a strong role of the binaural cues in spectrally degraded speech, when the target and interfering speech are more likely to be confused. The nearly normal binaural benefits under present simulation conditions and the lack of order of processing effect further suggest that preservation of binaural cues is likely to improve performance in bilaterally implanted recipients. PMID:19894832

  7. 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.

  8. 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.

  9. 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.

  10. 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).

  11. 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.

  12. Signal detection techniques applied to the Chandler wobble

    NASA Technical Reports Server (NTRS)

    Gross, R. S.

    1985-01-01

    A sudden excitation event of the Chandler wobble should induce the earth's rotation pole to undergo damped harmonic motion. This type of motion has been searched for in the observations of the Chandler wobble using techniques based upon the concept of a matched filter. Although the signal detection techniques used here were not sensitive enough to detect any such isolated sudden excitation events, the result that was obtained is consistent with a randomly excited model of the Chandler wobble.

  13. RMOD: a tool for regulatory motif detection in signaling network.

    PubMed

    Kim, Jinki; Yi, Gwan-Su

    2013-01-01

    Regulatory motifs are patterns of activation and inhibition that appear repeatedly in various signaling networks and that show specific regulatory properties. However, the network structures of regulatory motifs are highly diverse and complex, rendering their identification difficult. Here, we present a RMOD, a web-based system for the identification of regulatory motifs and their properties in signaling networks. RMOD finds various network structures of regulatory motifs by compressing the signaling network and detecting the compressed forms of regulatory motifs. To apply it into a large-scale signaling network, it adopts a new subgraph search algorithm using a novel data structure called path-tree, which is a tree structure composed of isomorphic graphs of query regulatory motifs. This algorithm was evaluated using various sizes of signaling networks generated from the integration of various human signaling pathways and it showed that the speed and scalability of this algorithm outperforms those of other algorithms. RMOD includes interactive analysis and auxiliary tools that make it possible to manipulate the whole processes from building signaling network and query regulatory motifs to analyzing regulatory motifs with graphical illustration and summarized descriptions. As a result, RMOD provides an integrated view of the regulatory motifs and mechanism underlying their regulatory motif activities within the signaling network. RMOD is freely accessible online at the following URL: http://pks.kaist.ac.kr/rmod. PMID:23874612

  14. Detection of essential hypertension with physiological signals from wearable devices.

    PubMed

    Ghosh, Arindam; Torres, Juan Manuel Mayor; Danieli, Morena; Riccardi, Giuseppe

    2015-08-01

    Early detection of essential hypertension can support the prevention of cardiovascular disease, a leading cause of death. The traditional method of identification of hypertension involves periodic blood pressure measurement using brachial cuff-based measurement devices. While these devices are non-invasive, they require manual setup for each measurement and they are not suitable for continuous monitoring. Research has shown that physiological signals such as Heart Rate Variability, which is a measure of the cardiac autonomic activity, is correlated with blood pressure. Wearable devices capable of measuring physiological signals such as Heart Rate, Galvanic Skin Response, Skin Temperature have recently become ubiquitous. However, these signals are not accurate and are prone to noise due to different artifacts. In this paper a) we present a data collection protocol for continuous non-invasive monitoring of physiological signals from wearable devices; b) we implement signal processing techniques for signal estimation; c) we explore how the continuous monitoring of these physiological signals can be used to identify hypertensive patients; d) We conduct a pilot study with a group of normotensive and hypertensive patients to test our techniques. We show that physiological signals extracted from wearable devices can distinguish between these two groups with high accuracy. PMID:26738172

  15. Fault Detection of Gearbox from Inverter Signals Using Advanced Signal Processing Techniques

    NASA Astrophysics Data System (ADS)

    Pislaru, C.; Lane, M.; Ball, A. D.; Gu, F.

    2012-05-01

    The gear faults are time-localized transient events so time-frequency analysis techniques (such as the Short-Time Fourier Transform, Wavelet Transform, motor current signature analysis) are widely used to deal with non-stationary and nonlinear signals. Newly developed signal processing techniques (such as empirical mode decomposition and Teager Kaiser Energy Operator) enabled the recognition of the vibration modes that coexist in the system, and to have a better understanding of the nature of the fault information contained in the vibration signal. However these methods require a lot of computational power so this paper presents a novel approach of gearbox fault detection using the inverter signals to monitor the load, rather than the motor current. The proposed technique could be used for continuous monitoring as well as on-line damage detection systems for gearbox maintenance.

  16. The Mirror Effect and Mixture Signal Detection Theory

    ERIC Educational Resources Information Center

    DeCarlo, Lawrence T.

    2007-01-01

    The mirror effect for word frequency refers to the finding that low-frequency words have higher hit rates and lower false alarm rates than high-frequency words. This result is typically interpreted in terms of conventional signal detection theory (SDT), in which case it indicates that the order of the underlying old item distributions mirrors…

  17. 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...

  18. Signal detection in conditions of everyday life traffic dilemmas.

    PubMed

    Rosenbloom, Tova; Wolf, Yuval

    2002-11-01

    This paper shows how the paradigm of signal detection could serve as a viable means for the analysis of drivers' choices in conditions of everyday life traffic dilemmas. The participants were 28 drivers, most of them professional, who spend at least 6 h a day on the road. All agreed to have a note-taking silent passenger for the entire journey, every day during a period of 3-4 weeks. All completed the sensation-seeking questionnaire. Their 'to do or not to do' choices in conditions of four (out of a total of six) traffic dilemmas (amber light, distance keeping, stopping in road-crossing and merging in routes) were analyzable in terms of a modification of the paradigm of signal detection. In accord with the basics of the paradigm of signal detection, the rate of success of the drivers to detect signals of danger on the road (perceptual sensitivity) fell into the range of partial uncertainty (more than 50% and not too much above this level)! The choices made by thrill-and-adventure-seeking drivers were more lenient than the choices of the drivers who scored lower on this dimension. PMID:12371781

  19. 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

  20. 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.

  1. Coherent stochastic oscillations enhance signal detection in spiking neurons

    PubMed Central

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

    2016-01-01

    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. PMID:19792163

  2. Signal enhancement in electronic detection of DNA hybridization

    NASA Astrophysics Data System (ADS)

    Gentil, C.; Philippin, G.; Bockelmann, U.

    2007-01-01

    Electronic detection of the specific recognition between complementary DNA sequences is investigated. DNA probes are immobilized at different lateral positions on a Poly( L -lysine)-coated surface of an integrated silicon transistor array. Hybridization and field effect detection are done with the solid surface immersed in electrolyte solutions. Differential measurements are performed, where DNA hybridization leads to surface potential shifts between the transistors of the array. We experimentally show that these differential signals of hybridization can be enhanced significantly by changing the salt concentration between hybridization and detection.

  3. Automatic detection of service initiation signals used in bars

    PubMed Central

    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. PMID:24009594

  4. 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. PMID:24009594

  5. 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

  6. Single photon radioluminescence. II. Signal detection and biological applications.

    PubMed Central

    Shahrokh, Z.; Bicknese, S.; Shohet, S. B.; Verkman, A. S.

    1992-01-01

    A quantitative theory for excitation of fluorescent molecules by beta decay electrons is reported in the accompanying manuscript; experimental detection methods and biological applications are reported here. The single photon signals produced by an excited fluorophore (single photon radioluminescence, SPR) provide quantitative information about the distance between radioisotope and fluorophore. Instrumentation was constructed for SPR signal detection. Photons produced in a 0.5-ml sample volume were detected by a cooled photomultiplier and photon counting electronics. To minimize electronic noise and drift for detection of very small SPR signals, a mechanical light chopper was used for gated-signal detection, and a pulse height analyzer for noise rejection. SPR signals of approximately 1 cps were reproducibly measurable. The influence of inner filter effect, sample turbidity, and fluorophore environment (lipid, protein, and carbohydrate) on SPR signals were evaluated experimentally. SPR was then applied to measure lipid exchange kinetics, ligand binding, and membrane transport, and to determine an intermolecular distance in an intact membrane. (a. Lipid exchange kinetics.) Transfer of 12-anthroyloxystearic acid (12-AS) from sonicated lipid vesicles and micelles to vesicles containing 3H-cholesterol was measured from the time course of increasing SPR signal. At 22 degrees C, the half-times for 12-AS transfer from vesicles and micelles were 3.3 and 1.1 min, respectively. (b. Ligand binding.) Binding of 3H-oleic acid to albumin in solution, and 3H-2,2'-dihydro-4,4'-diisothiocyanodisulfonic stilbene (3H-H2DIDS) to band 3 on the erythrocyte membranes were detected by the radioluminescence of the intrinsic tryptophans. The SPR signal from 5 microCi 3H-oleic acid bound to 0.3 mM albumin decreased from 13 +/- 2 cps to 3 +/- 2 cps upon addition of nonradioactive oleic acid, giving 2.7 high affinity oleic acid binding sites per albumin. The SPR signal from 1 microCi 3H-H2DIDS

  7. Single photon radioluminescence. II. Signal detection and biological applications.

    PubMed

    Shahrokh, Z; Bicknese, S; Shohet, S B; Verkman, A S

    1992-11-01

    A quantitative theory for excitation of fluorescent molecules by beta decay electrons is reported in the accompanying manuscript; experimental detection methods and biological applications are reported here. The single photon signals produced by an excited fluorophore (single photon radioluminescence, SPR) provide quantitative information about the distance between radioisotope and fluorophore. Instrumentation was constructed for SPR signal detection. Photons produced in a 0.5-ml sample volume were detected by a cooled photomultiplier and photon counting electronics. To minimize electronic noise and drift for detection of very small SPR signals, a mechanical light chopper was used for gated-signal detection, and a pulse height analyzer for noise rejection. SPR signals of approximately 1 cps were reproducibly measurable. The influence of inner filter effect, sample turbidity, and fluorophore environment (lipid, protein, and carbohydrate) on SPR signals were evaluated experimentally. SPR was then applied to measure lipid exchange kinetics, ligand binding, and membrane transport, and to determine an intermolecular distance in an intact membrane. (a. Lipid exchange kinetics.) Transfer of 12-anthroyloxystearic acid (12-AS) from sonicated lipid vesicles and micelles to vesicles containing 3H-cholesterol was measured from the time course of increasing SPR signal. At 22 degrees C, the half-times for 12-AS transfer from vesicles and micelles were 3.3 and 1.1 min, respectively. (b. Ligand binding.) Binding of 3H-oleic acid to albumin in solution, and 3H-2,2'-dihydro-4,4'-diisothiocyanodisulfonic stilbene (3H-H2DIDS) to band 3 on the erythrocyte membranes were detected by the radioluminescence of the intrinsic tryptophans. The SPR signal from 5 microCi 3H-oleic acid bound to 0.3 mM albumin decreased from 13 +/- 2 cps to 3 +/- 2 cps upon addition of nonradioactive oleic acid, giving 2.7 high affinity oleic acid binding sites per albumin. The SPR signal from 1 microCi 3H-H2DIDS

  8. 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.

  9. 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

  10. Signal Improvement Strategies for Fluorescence Detection of Biomacromolecules.

    PubMed

    Luan, Chengxin; Yang, Zixue; Chen, Baoan

    2016-05-01

    For analysis of biomacromolecules, a sensitive, specified and reliable method is indispensable. Fluorescent dyes or fluorophores have been widely used as mediums to obtain readout signals in various assays or bioimaging because of their versatilities such as biocompatibility. Those fluorescent dyes based techniques manipulate many molecular interactions for analysis of biomacromolecules including antibody-protein interaction, base complementation, glycan-lectin interaction, etc. The strategies to manipulate those molecular interactions are various and always updating due to the development of biotechnological tools and instruments. In this minireview, we summarize the state of the art of signal improvement techniques for fluorescence detection of biomacromolecules especially proteins and nucleic acids. We focus on the principle and mechanism of those techniques for fluorescence detection of biomacromolecules. We also discuss the future trend of the techniques for fluorescence detection of biomacromolecules. PMID:27063869

  11. An Improved Network Strain Filter for Detecting Transient Deformation Signals

    NASA Astrophysics Data System (ADS)

    Ohtani, R.; McGuire, J.; Segall, P.

    2008-12-01

    We have developed a tool to detect transient signals such as aseismic fault slip and magmatic intrusion automatically from large-scale (principally GPS) geodetic arrays, referred to as a Network Strain Filter (NSF). The NSF is capable of detecting transient signals in large data sets which may be difficult to identify by visual inspection of individual time series. The underlying principle is to exploit the spatially coherent nature of tectonic signals. The NSF models GPS displacement time series as a sum of contributions from tectonic transients, steady motion due to secular deformation, site-specific local benchmark motion, reference frame errors, and white noise. Transient deformation is represented by a spatial wavelet basis with time varying coefficients estimated using Kalman filtering techniques. A "hyperparameter" is also estimated to constrain the amount of temporal smoothness of the tectonic deformation. As station distribution is irregular and wavelets have local support (non-zero only over a localized domain), the design matrix is generally ill-conditioned. We investigate two strategies for regularizing the problem. The first is explicit spatial smoothing of the transient deformation. The second is to simply exclude wavelet bases that don't span some minimum number of stations. In this case, the smallest wavelet scale is determined such that the residual variance is consistent with the a priori errors of the data. Similarly the degree of spatial smoothing is determined by a priori knowledge of the data errors. To test the performance of the NSF, we carried out numerical tests using the southern California Integrated GPS Network (SCIGN) station distribution with synthetic transients of variable signal to noise ratio. We tested a six-year-long time series with a slow slip event with a duration of three years. Due to the long duration of the transient event, the contributions from secular motion and benchmark wobble make it difficult to identify the

  12. 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. PMID:24727491

  13. 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.

  14. Binaural loudness summation for speech presented via earphones and loudspeaker with and without visual cuesa)

    PubMed Central

    Epstein, Michael; Florentine, Mary

    2012-01-01

    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. PMID:22559371

  15. 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. PMID:26218307

  16. 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

  17. 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

  18. Detection of weak signals in memory thermal baths

    NASA Astrophysics Data System (ADS)

    Jiménez-Aquino, J. I.; Velasco, R. M.; Romero-Bastida, M.

    2014-11-01

    The nonlinear relaxation time and the statistics of the first passage time distribution in connection with the quasideterministic approach are used to detect weak signals in the decay process of the unstable state of a Brownian particle embedded in memory thermal baths. The study is performed in the overdamped approximation of a generalized Langevin equation characterized by an exponential decay in the friction memory kernel. A detection criterion for each time scale is studied: The first one is referred to as the receiver output, which is given as a function of the nonlinear relaxation time, and the second one is related to the statistics of the first passage time distribution.

  19. 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.

  20. 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.

  1. Improving the performance of cardiac abnormality detection from PCG signal

    NASA Astrophysics Data System (ADS)

    Sujit, N. R.; Kumar, C. Santhosh; Rajesh, C. B.

    2016-03-01

    The Phonocardiogram (PCG) signal contains important information about the condition of heart. Using PCG signal analysis prior recognition of coronary illness can be done. In this work, we developed a biomedical system for the detection of abnormality in heart and methods to enhance the performance of the system using SMOTE and AdaBoost technique have been presented. Time and frequency domain features extracted from the PCG signal is input to the system. The back-end classifier to the system developed is Decision Tree using CART (Classification and Regression Tree), with an overall classification accuracy of 78.33% and sensitivity (alarm accuracy) of 40%. Here sensitivity implies the precision obtained from classifying the abnormal heart sound, which is an essential parameter for a system. We further improve the performance of baseline system using SMOTE and AdaBoost algorithm. The proposed approach outperforms the baseline system by an absolute improvement in overall accuracy of 5% and sensitivity of 44.92%.

  2. 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.

  3. 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.

  4. Exploring Sampling in the Detection of Multicategory EEG Signals

    PubMed Central

    Siuly, Siuly; Kabir, Enamul; Wang, Hua; Zhang, Yanchun

    2015-01-01

    The paper presents a structure based on samplings and machine leaning techniques for the detection of multicategory EEG signals where random sampling (RS) and optimal allocation sampling (OS) are explored. In the proposed framework, before using the RS and OS scheme, the entire EEG signals of each class are partitioned into several groups based on a particular time period. The RS and OS schemes are used in order to have representative observations from each group of each category of EEG data. Then all of the selected samples by the RS from the groups of each category are combined in a one set named RS set. In the similar way, for the OS scheme, an OS set is obtained. Then eleven statistical features are extracted from the RS and OS set, separately. Finally this study employs three well-known classifiers: k-nearest neighbor (k-NN), multinomial logistic regression with a ridge estimator (MLR), and support vector machine (SVM) to evaluate the performance for the RS and OS feature set. The experimental outcomes demonstrate that the RS scheme well represents the EEG signals and the k-NN with the RS is the optimum choice for detection of multicategory EEG signals. PMID:25977705

  5. Exploring sampling in the detection of multicategory EEG signals.

    PubMed

    Siuly, Siuly; Kabir, Enamul; Wang, Hua; Zhang, Yanchun

    2015-01-01

    The paper presents a structure based on samplings and machine leaning techniques for the detection of multicategory EEG signals where random sampling (RS) and optimal allocation sampling (OS) are explored. In the proposed framework, before using the RS and OS scheme, the entire EEG signals of each class are partitioned into several groups based on a particular time period. The RS and OS schemes are used in order to have representative observations from each group of each category of EEG data. Then all of the selected samples by the RS from the groups of each category are combined in a one set named RS set. In the similar way, for the OS scheme, an OS set is obtained. Then eleven statistical features are extracted from the RS and OS set, separately. Finally this study employs three well-known classifiers: k-nearest neighbor (k-NN), multinomial logistic regression with a ridge estimator (MLR), and support vector machine (SVM) to evaluate the performance for the RS and OS feature set. The experimental outcomes demonstrate that the RS scheme well represents the EEG signals and the k-NN with the RS is the optimum choice for detection of multicategory EEG signals. PMID:25977705

  6. 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

  7. 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

  8. 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

  9. Plant neighbor detection through touching leaf tips precedes phytochrome signals.

    PubMed

    de Wit, Mieke; Kegge, Wouter; Evers, Jochem B; Vergeer-van Eijk, Marleen H; Gankema, Paulien; Voesenek, Laurentius A C J; Pierik, Ronald

    2012-09-01

    Plants in dense vegetation compete for resources, including light, and optimize their growth based on neighbor detection cues. The best studied of such behaviors is the shade-avoidance syndrome that positions leaves in optimally lit zones of a vegetation. Although proximate vegetation is known to be sensed through a reduced ratio between red and far-red light, we show here through computational modeling and manipulative experiments that leaves of the rosette species Arabidopsis thaliana first need to move upward to generate sufficient light reflection potential for subsequent occurrence and perception of a reduced red to far-red ratio. This early hyponastic leaf growth response is not induced by known neighbor detection cues under both climate chamber and natural sunlight conditions, and we identify a unique way for plants to detect future competitors through touching of leaf tips. This signal occurs before light signals and appears to be the earliest means of above-ground plant-plant signaling in horizontally growing rosette plants. PMID:22908260

  10. SIDRA: a blind algorithm for signal detection in photometric surveys

    NASA Astrophysics Data System (ADS)

    Mislis, D.; Bachelet, E.; Alsubai, K. A.; Bramich, D. M.; Parley, N.

    2016-01-01

    We present the Signal Detection using Random-Forest Algorithm (SIDRA). SIDRA is a detection and classification algorithm based on the Machine Learning technique (Random Forest). The goal of this paper is to show the power of SIDRA for quick and accurate signal detection and classification. We first diagnose the power of the method with simulated light curves and try it on a subset of the Kepler space mission catalogue. We use five classes of simulated light curves (CONSTANT, TRANSIT, VARIABLE, MLENS and EB for constant light curves, transiting exoplanet, variable, microlensing events and eclipsing binaries, respectively) to analyse the power of the method. The algorithm uses four features in order to classify the light curves. The training sample contains 5000 light curves (1000 from each class) and 50 000 random light curves for testing. The total SIDRA success ratio is ≥90 per cent. Furthermore, the success ratio reaches 95-100 per cent for the CONSTANT, VARIABLE, EB and MLENS classes and 92 per cent for the TRANSIT class with a decision probability of 60 per cent. Because the TRANSIT class is the one which fails the most, we run a simultaneous fit using SIDRA and a Box Least Square (BLS)-based algorithm for searching for transiting exoplanets. As a result, our algorithm detects 7.5 per cent more planets than a classic BLS algorithm, with better results for lower signal-to-noise light curves. SIDRA succeeds to catch 98 per cent of the planet candidates in the Kepler sample and fails for 7 per cent of the false alarms subset. SIDRA promises to be useful for developing a detection algorithm and/or classifier for large photometric surveys such as TESS and PLATO exoplanet future space missions.

  11. Effect of monaural and binaural stimulation on cytoplasmic RNA content in cells of the central nucleus of the cat inferior colliculus.

    PubMed

    Shmigidina, G N

    1981-01-01

    A cytophotometric study of sections stained with gallocyanin and chrome alum showed that monaural stimulation for 2 h and binaural stimulation for 1.5 h with rhythmic noise signals led to a marked increase in the cytoplasmic RNA content per cell in the principal and large multipolar neurons of the dorsal and ventral parts of the ventrolateral region of the central nucleus of the inferior colliculus. The increase in cytoplasmic RNA content in the principal cells of the ipsi- and contralateral parts of this nucleus relative to the stimulated ear in the case of monaural stimulation and the increase in RNA content in response to binaural stimulation suggests a uniform distribution of bilaterally converging connections from the lower nuclei of the auditory system on the principal cells. The increase in cytoplasmic RNA in the large multipolar cells of the contralateral central nucleus in response to monaural stimulation is evidence of the predominantly contralateral projection to these cells. The results are evidence of convergence of binaural influences on the principal and large multipolar cells of the central nucleus of the inferior colliculus. PMID:6173796

  12. In Vivo Detection of Intracellular Signaling Pathways in Developing Thymocytes

    PubMed Central

    Zúñiga-Pflücker, Juan Carlos

    2000-01-01

    Information regarding the intracellular signaling processes that occur during the development of T cells has largely been obtained with the use of transgenic mouse models, which although providing invaluable information are time consuming and costly. To this end, we have developed a novel system that facilitates the In Vivo analysis of signal transduction pathways during T-lymphocyte development. This approach uses reporter-plasmids for the detection of intracellular signals mediated by the mitogen-activated protein kinase or cyclic AMP-dependent protein kinase. Reporter-plasmids are transfected into thymocytes in fetal thymic organ culture by accelerated DNA/particle bombardment (gene gun), and the activation of a signaling pathway is determined in the form of a standard luciferase assay. Importantly, this powerful technique preserves the structural integrity of the thymus, and will provide an invaluable tool to study how thymocytes respond to normal environmental stimuli encountered during differentiation within the thymic milieu. Thus, this method allows for the monitoring of signals that occur in a biological time frame, such as during differentiation, and within the natural environment of differentiating cells. PMID:11293810

  13. Nasal chemosensory cells use bitter taste signaling to detect irritants and bacterial signals

    PubMed Central

    Tizzano, Marco; Gulbransen, Brian D.; Vandenbeuch, Aurelie; Clapp, Tod R.; Herman, Jake P.; Sibhatu, Hiruy M.; Churchill, Mair E. A.; Silver, Wayne L.; Kinnamon, Sue C.; Finger, Thomas E.

    2010-01-01

    The upper respiratory tract is continually assaulted with harmful dusts and xenobiotics carried on the incoming airstream. Detection of such irritants by the trigeminal nerve evokes protective reflexes, including sneezing, apnea, and local neurogenic inflammation of the mucosa. Although free intra-epithelial nerve endings can detect certain lipophilic irritants (e.g., mints, ammonia), the epithelium also houses a population of trigeminally innervated solitary chemosensory cells (SCCs) that express T2R bitter taste receptors along with their downstream signaling components. These SCCs have been postulated to enhance the chemoresponsive capabilities of the trigeminal irritant-detection system. Here we show that transduction by the intranasal solitary chemosensory cells is necessary to evoke trigeminally mediated reflex reactions to some irritants including acyl–homoserine lactone bacterial quorum-sensing molecules, which activate the downstream signaling effectors associated with bitter taste transduction. Isolated nasal chemosensory cells respond to the classic bitter ligand denatonium as well as to the bacterial signals by increasing intracellular Ca2+. Furthermore, these same substances evoke changes in respiration indicative of trigeminal activation. Genetic ablation of either Gα-gustducin or TrpM5, essential elements of the T2R transduction cascade, eliminates the trigeminal response. Because acyl–homoserine lactones serve as quorum-sensing molecules for Gram-negative pathogenic bacteria, detection of these substances by airway chemoreceptors offers a means by which the airway epithelium may trigger an epithelial inflammatory response before the bacteria reach population densities capable of forming destructive biofilms. PMID:20133764

  14. Intelligent signal analysis methodologies for nuclear detection, identification and attribution

    NASA Astrophysics Data System (ADS)

    Alamaniotis, Miltiadis

    Detection and identification of special nuclear materials can be fully performed with a radiation detector-spectrometer. Due to several physical and computational limitations, development of fast and accurate radioisotope identifier (RIID) algorithms is essential for automated radioactive source detection and characterization. The challenge is to identify individual isotope signatures embedded in spectral signature aggregation. In addition, background and isotope spectra overlap to further complicate the signal analysis. These concerns are addressed, in this thesis, through a set of intelligent methodologies recognizing signature spectra, background spectrum and, subsequently, identifying radionuclides. Initially, a method for detection and extraction of signature patterns is accomplished by means of fuzzy logic. The fuzzy logic methodology is applied on three types of radiation signal processing applications, where it exhibits high positive detection, low false alarm rate and very short execution time, while outperforming the maximum likelihood fitting approach. In addition, an innovative Pareto optimal multiobjective fitting of gamma ray spectra using evolutionary computing is presented. The methodology exhibits perfect identification while performs better than single objective fitting. Lastly, an innovative kernel based machine learning methodology was developed for estimating natural background spectrum in gamma ray spectra. The novelty of the methodology lies in the fact that it implements a data based approach and does not require any explicit physics modeling. Results show that kernel based method adequately estimates the gamma background, but algorithm's performance exhibits a strong dependence on the selected kernel.

  15. Detectability of the Reflection Signal from Inner Planets

    NASA Technical Reports Server (NTRS)

    Borucki, W. J.; Jenkins, J. M.; Scargle, J.; Koch, D.; Doyle, L. R.; Cuzzi, Jeffrey (Technical Monitor)

    1996-01-01

    Mayor and Queloz (1996) and Marcy and Butler (1996) have found massive planets with orbital periods Tp=approx.4 days around two solar-like stars (51 Pegasi and v Andromeda). These planets are most likely similar in size and composition to the gas giants in our solar system (Burrows et al 1996). Based on this expectation and assuming the same albedo as Jupiter, we examined the feasibility of searching for similar planets with a dedicated space-based 1-m telescope. The Kepler mission will survey approximately 70,000 main-sequence dwarf stars from 9 to 14 mag continuously for four years to detect transiting Earthlike planets. Based on the detection statistics of Marcy and Butler, we expect to detect 1400 inner-orbit giant planets. Such planets in a much wider range of orbital inclinations (i) will produce nearly sinusoidal modulations of the star light flux due to the varying planetary phases. The relative signal amplitudes are of order 2x10(exp -5) and decrease as Tp(exp 4/3) for i >> 0deg. We estimated the expected signal to noise ratio (SNR) using the solar irradiance measurements from the ACRIM 1 experiment along with expected shot and detector noises. The figure shows SNR as a function of Tp for a 12 mag star, and indicates the planet radius required for detection. The survey will be sensitive to planets with periods from 12 hr to approx.8 days at the 6 sigma level.

  16. Integrated Heterodyne MOEMS for detection of low intensity signals

    NASA Astrophysics Data System (ADS)

    Elman, Noel M.; Krylov, Slava; Sternheim, Marek; Shacham-Diamand, Yosi

    2006-01-01

    A novel MEMS-based modulation scheme is presented as a method to enhance the signal-to-noise ratio (SNR) of silicon photodiodes adapted for the detection of light-emitting bio-reporter signals. Photodiodes are an attractive photodetector choice because they are VLSI compatible, easily miniaturized, highly scalable, and inexpensive. Silicon photodiodes exhibit a wide response range extending from the ultraviolet (UV) to the near infrared (IR) part of the spectrum, which in principle is appropriate for sensing low intensity optical signals. Silicon photodiodes, however, exhibit limited sensitivity to optical dc signals, as the magnitude of the low frequency noise is comparable to signal magnitude. Optical modulation prior to photodetection overcomes the inherent low frequency noise of photodetectors and system detection circuits. The enhancement scheme is based on a design of high frequency optical modulators that operate in the 1-2 kHz range in order to overcome the low frequency spectral noise. We have denominated this MEMS-based scheme Integrated Heterodyne Optical System (IHOS). The modulation efficiency of the proposed architecture can reach up to 50 percent. In order to implement the MOEMS optical modulators, a new two-mask fabrication process was developed that combines high-aspect ratio and low aspect ratio structures at the same device layer (aspect ratio is defined as a ratio between the structure height to its width). Long stroke electrostatic combdrive actuators integrated with folded flexures (high aspect-ratio) were fabricated together to drive large aperture shutters (low aspect ratio). We have denominated this process MASIS (Multiple Aspect Ratio Structural Integration). Under resonant excitation at approximately 1 kHz, MOEMS modulators demonstrated maximum displacement of about 40 microns at an actuation voltage of 15 V peak in air, and 3.5 V peak in vacuum (8 mTorr). Results of analytical solutions and finite element analysis (FEA) simulations are

  17. Automatic fall detection using wearable biomedical signal measurement terminal.

    PubMed

    Nguyen, Thuy-Trang; Cho, Myeong-Chan; Lee, Tae-Soo

    2009-01-01

    In our study, we developed a mobile waist-mounted device which can monitor the subject's acceleration signal and detect the fall events in real-time with high accuracy and automatically send an emergency message to a remote server via CDMA module. When fall event happens, the system also generates an alarm sound at 50Hz to alarm other people until a subject can sit up or stand up. A Kionix KXM52-1050 tri-axial accelerometer and a Bellwave BSM856 CDMA standalone modem were used to detect and manage fall events. We used not only a simple threshold algorithm but also some supporting methods to increase an accuracy of our system (nearly 100% in laboratory environment). Timely fall detection can prevent regrettable death due to long-lie effect; therefore increase the independence of elderly people in an unsupervised living environment. PMID:19964661

  18. 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

  19. 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.

  20. 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

  1. 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.

  2. 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.

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

    PubMed

    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

  4. Median recoil direction as a WIMP directional detection signal

    NASA Astrophysics Data System (ADS)

    Green, Anne M.; Morgan, Ben

    2010-03-01

    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 ˜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.

  5. Stochastic model for detection of signals in noise.

    PubMed

    Klein, Stanley A; Levi, Dennis M

    2009-11-01

    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

  6. 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.

  7. 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

  8. 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.

  9. 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.

  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. 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. PMID:11051502

  12. 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

  13. Transduction of nanovolt signals: Limits of electric-field detection

    NASA Astrophysics Data System (ADS)

    Kalmijn, J.

    1989-11-01

    Life scientists discussed the extreme electrical sensitivity of marine sharks, skates, and rays. After reviewing the results of earlier studies on the electric sense at the animal and system levels, the participants discussed the basic process of signal transduction in terms of voltage-sensitive ionic channels. Struck by the small charge displacements needed for excitation, they strongly recommended that sensory biologists, physiologists, and biophysicists join in a concerted effort to initiate new research on the ionic mechanisms of electric field detection. To obtain detailed information on the electroreceptive membrane and its ionic channels, high resolution recording techniques will be mandatory.

  14. Model-Based Signal Processing: Correlation Detection With Synthetic Seismograms

    SciTech Connect

    Rodgers, A; Harris, D; Pasyanos, M; Blair, S; Matt, R

    2006-08-30

    Recent applications of correlation methods to seismological problems illustrate the power of coherent signal processing applied to seismic waveforms. Examples of these applications include detection of low amplitude signals buried in ambient noise and cross-correlation of sets of waveforms to form event clusters and accurately measure delay times for event relocation and/or earth structure. These methods rely on the exploitation of the similarity of individual waveforms and have been successfully applied to large sets of empirical observations. However, in cases with little or no empirical event data, such as aseismic regions or exotic event types, correlation methods with observed seismograms will not be possible due to the lack of previously observed similar waveforms. This study uses model-based signals computed for three-dimensional (3D) Earth models to form the basis for correlation detection. Synthetic seismograms are computed for fully 3D models estimated from the Markov Chain Monte-Carlo (MCMC) method. MCMC uses stochastic sampling to fit multiple seismological data sets. Rather than estimate a single ''optimal'' model, MCMC results in a suite of models that sample the model space and incorporates uncertainty through variability of the models. The variability reflects our ignorance of Earth structure, due to limited resolution, data and modeling errors, and produces variability in the seismic waveform response. Model-based signals are combined using a subspace method where the synthetic signals are decomposed into an orthogonal basis by singular-value decomposition (SVD) and the observed waveforms are represented with a linear combination of a sub-set of eigenvectors (signals) associated with the most significant eigenvalues. We have demonstrated the method by modeling long-period (80-10 seconds) regional seismograms for a moderate (M{approx}5) earthquake near the China-North Korea border. Synthetic seismograms are computed with the Spectral Element Method

  15. Signal detection methods for measurement of utility in animals1

    PubMed Central

    Wright, Anthony A.; Nevin, John A.

    1974-01-01

    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. PMID:16811750

  16. 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.

  17. 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

  18. Wavelet neural network for detection of signals in communications

    NASA Astrophysics Data System (ADS)

    Gomez-Sanchez, Raquel; Andina, Diego

    1998-03-01

    Our objective is the design and simulation of an efficient system for detection of signals in communications in terms of speed and computational complexity. The proposed scheme takes advantage of two powerful frameworks in signal processing: wavelets and neural networks. The decision system will take a decision based on the computation of the a prior probabilities of the input signal. For the estimation of such probability density functions, a wavelet neural network has been chosen. The election has risen under the following considerations: (a) neural networks have been established as a general approximation tool for fitting nonlinear models from input/output data and (b) the increasing popularity of the wavelet decomposition as a powerful tool for approximation. The integration of the above factors leads to the wavelet neural network concept. This network preserves the universal approximation property of wavelet series, with the advantage of the speed and efficient computation of a neural network architecture. The topology and learning algorithm of the network will provide an efficient approximation to the required probability density functions.

  19. Correntropy measures to detect daytime sleepiness from EEG signals.

    PubMed

    Melia, Umberto; Guaita, Marc; Vallverdú, Montserrat; Montserrat, Josep M; Vilaseca, Isabel; Salamero, Manel; Gaig, Carles; Caminal, Pere; Santamaria, Joan

    2014-10-01

    Excessive daytime sleepiness (EDS) is one of the main symptoms of several sleep related disorders and has a great impact on patients' lives. While many studies have been carried out in order to assess daytime sleepiness, automatic EDS detection still remains an open problem. In this work, a novel approach to this issue based on correntropy function analysis of EEG signals was proposed in order to detect patients suffering from EDS. Multichannel EEG signals were recorded during five Maintenance of Wakefulness Tests (MWT) and Multiple Sleep Latency Tests (MSLT) alternated throughout the day for patients suffering from sleep disordered breathing (SDB). A group of 20 patients with EDS was compared with a group of 20 patients without daytime sleepiness (WDS), by analyzing 60 s EEG windows in a waking state. Measures obtained from the cross-correntropy function (CCORR) and auto-correntropy function (ACORR) were calculated in the EEG frequency bands: δ, 0.1-4 Hz; θ, 4-8 Hz; α, 8-12 Hz; β, 12-30 Hz; total band TB, 0.1-45 Hz. These functions permitted the quantification of complex signal properties and the non-linear couplings between different areas of the scalp. Statistical differences between EDS and WDS groups were mainly found in the β band during MSLT events (p-value < 0.0001). The WDS group presented more complexity in the occipital zone than the EDS group, while a stronger nonlinear coupling between the occipital and frontal regions was detected in EDS patients than in the WDS group. At best, ACORR and CCORR measures yielded sensitivity and specificity above 80% and the area under ROC curve (AUC) was above 0.85 in classifying EDS and WDS patients. These performances represent an improvement with respect to classical EEG indices applied in the same database (sensitivity and specificity were never above 80% and AUC was under 0.75). PMID:25237837

  20. 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

  1. Diffraction tomographic signal processing algorithms for tunnel detection

    SciTech Connect

    Witten, A.J.

    1993-08-01

    Signal processing algorithms have been developed for wave based imaging using diffraction tomography. The basis for this image reconstruction procedure is the generalized projection slice theorem (GPST) which, for homogeneous waves, is an analytic relationship between the spatial Fourier transform of the acquired data and the spatial Fourier transform of the spatial profile (object function) of the object being imaged. Imaging within geophysical diffraction tomography when only homogeneous waves are considered can then be accomplished by inversion of the GPST using standard numerical techniques. In an attenuating background medium or when eddy currents or static fields are considered, a generalized GPST can be derived that involves both real and complex spatial frequencies. In this case, direct Fourier inversion is not possible because of the presence of the complex frequencies. Although direct inversion and, hence, complete imaging is not possible for such cases, the generalized CPST`S can be used to analytically shift the location of data templates matched to specified targets and these templates can, in turn, be correlated with acquired data to detect and estimate the location of the specified targets. Since GPST`s are used directly in the detection problem, there is no need to numerically invert the intergal transform of the object function. For this reason, target detection can be accomplished in a computationally efficient manner independent of the type of measurement or background geologic conditions. A number of GPST`s are derived and the use of GPST`s for both imaging and detection of subsurface voids is demonstrated in several recent applications.

  2. Reinforcer control and human signal-detection performance.

    PubMed Central

    Johnstone, V; Alsop, B

    2000-01-01

    Eight humans participated in a two-choice signal-detection task in which stimulus disparity was varied over four levels. Two procedures arranged asymmetrical numbers of reinforcers received for correct left- and right-key responses (the reinforcer ratio). The controlled procedure ensured that the obtained reinforcer ratio remained constant over changes in stimulus disparity, irrespective of subjects' performances. In the uncontrolled procedure, the asymmetrical reinforcer ratio could covary with subjects' performances. The receiver operating characteristic (ROC) patterns obtained from the controlled procedure approximated isobias functions predicted by criterion location measures of bias. The uncontrolled procedure produced variable ROC patterns that were somewhat like the isobias predictions made by likelihood ratio measures of bias; however, the obtained reinforcer ratio became more extreme as discriminability decreased. The obtained pattern of bias was directly related to the obtained reinforcer ratio. This research indicates that criterion location measures seem to be preferable indices of response bias. PMID:10866352

  3. Marginalized Particle Filter for Blind Signal Detection with Analog Imperfections

    NASA Astrophysics Data System (ADS)

    Yoshida, Yuki; Hayashi, Kazunori; Sakai, Hideaki; Bocquet, Wladimir

    Recently, the marginalized particle filter (MPF) has been applied to blind symbol detection problems over selective fading channels. The MPF can ease the computational burden of the standard particle filter (PF) while offering better estimates compared with the standard PF. In this paper, we investigate the application of the blind MPF detector to more realistic situations where the systems suffer from analog imperfections which are non-linear signal distortion due to the inaccurate analog circuits in wireless devices. By reformulating the system model using the widely linear representation and employing the auxiliary variable resampling (AVR) technique for estimation of the imperfections, the blind MPF detector is successfully modified to cope with the analog imperfections. The effectiveness of the proposed MPF detector is demonstrated via computer simulations.

  4. 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.

  5. 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.

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

    PubMed Central

    Critchfield, T S

    1993-01-01

    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

  7. Detection of signals by weighted integrate-and-dump filter

    NASA Technical Reports Server (NTRS)

    Sadr, R.

    1987-01-01

    A Weighted Integrate and Dump Filter (WIDF) is presented that results in reducing those losses in telemetry symbol signal to noise ratio (SNR) which occur in digital Integrate and Dump Filters (IDFs) when the samples are not phase locked to the input data symbol clock. The Minimum Mean Square Error (MMSE) criterion is used to derive a set of weights for approximating the analog integrate and dump filter, which is the matched filter for detection of signals in additive white Gaussian noise. This new digital matched filter results in considerable performance improvement compared to unweighted digital matched filters. An example is presented for a sampling rate of four times the symbol rate. As the sampling offset (or phase) varies with respect to the data symbol boundaries, the output SNR varies 1 dB for an unweighted IDF, but only 0.3 dB for the optimum WIDF, averaged over random data patterns. This improvement in performance relative to unweighted IDF means that significantly lower sampling and processing rates can be used for given telemetry symbol rates, resulting in reduced system cost.

  8. Technique for detecting a direct signal pulse from an underwater explosive source in a waveguide

    NASA Astrophysics Data System (ADS)

    Kostenko, K. V.; Kryukov, Yu. S.

    2016-01-01

    A technique for detecting direct signal pulses based on steep rising edges of acoustic pressure is developed. The technique consists in calculating the mirror derivative of the received signal and normalizing it in a specific manner. This makes it possible to amplify weak direct signals and suppress strong reflected ones. A key feature of this technique is that it ensures a high probability of detection of direct signal pulses while keeping the number of false detections at a minimum.

  9. 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.

  10. 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