bluuebunny/crossref_metadata_2025 huggingface dataset:
Spatial active noise reduction with multiple error microphones.
Authors: Rubin Ofira , Cherkassky Dani
Published: July 2011

Recently, research in the field of active noise control (ANC) has increased considerably. Currently there are three different approaches to extend the upper limiting frequency and attenuation zone of ANC systems. The first approach is to locate a single error microphone in close proximity to the noise source. This approach extends the upper limiting frequency but achieves local noise reduction. The second approach is to place a single error microphone at a remote point relative to the noise source. The problem with this approach is that due to coherence problems poor results are achieved. The third approach is .to place several error microphones around the noise source in various deployments. This approach, named as multiple error sensor technology (MEST), appears to be the most promising one. In this paper, three major phenomena were empirically investigated: the first is the contribution of MEST compared with a single error sensor, the second is the optimal deployment of the error microphones, and the third is the influence of the number of error microphones on the ANC performance. A significant improvement to ANC compared with classical single error microphone methods was achieved by applying MEST. Spatial broadband noise reduction of 6.4 dB(A) was demonstrated.
Aeroacoustic beamforming for airfoil trailing edge tonal noise sources.
Authors: Arcondoulis Elias J. G. , Doolan Con J. , Brooks Laura A. , Zander Anthony C.
Published: July 2011

Airfoils produce tonal and broadband noise at low to moderate Reynolds number flow conditions. The effect of variation in flow Reynolds number and airfoil angle of attack on the quantification and localization of the acoustic sources responsible for the observed tonal noise component is still uncertain. An investigation of the effect of Reynolds number, angle of attack, and acoustic frequency on the tonal noise sources will be presented. This study was performed using aeroacoustic beamforming in a small anechoic wind tunnel. Accurately locating the tonal noise source locations of an airfoil will improve knowledge of how airfoils produce tonal noise in this flow regime which will help the implementation of noise reduction techniques. In addition, some of the problems associated with beamforming low frequency noise sources and close proximity coherent tonal noise sources using conventional beamforming techniques and deconvolution algorithms will be addressed. [The authors would like to thank the School of Mechanical Engineering at the University of Adelaide for access and use of the facilities and equipment detailed in this presentation.]
Evidence for a plasma core during acoustic cavitation in sulfuric acid.
Authors: Suslick Kenneth S. , Xu Hangxun , Flannigan David J.
Published: July 2011

Extreme temperatures and pressures are produced through, acoustic cavitation: the formation, growth and collapse of bubbles in a liquid irradiated with high intensity ultrasound. Single bubbles have generally been assumed to give higher temperature conditions than bubble clouds, but confirmation from the single bubble sonoluminescence (SBSL) emission spectra has been problematic because SBSL typically produces featureless emission spectra that reveal little about the intra-cavity physical conditions or chemical processes. Here definitive evidence of the existence of a hot, highly energetic plasma core during SBSL is presented. From a luminescing bubble in sulfuric acid, excited state to excited state emission lines are observed both from noble gas ions (Ar+, Kr+, and Xe+) and from neutral atoms (Ne, Ar, Kr, and Xe). The excited states responsible for these emission lines range from 8.3 eV (for Xe) to 37.1 eV (for Ar+) above the ground state. Observation of emission lines allows for identification of intra-cavity species responsible for light emission; the energy levels and bandshapes of the emitters indicate that the plasma generated during cavitation is comprised of highly energetic atomic and ionic species with Ne as large as 10×D21/cc. Ionization and plasma can also be created during multi-bubble sonoluminescence in sulfuric acid.
Time resolved spectra of the transition to a sonoluminescing blackbody.
Authors: Putterman Seth , Kappus Brian , Khalid Shaz
Published: July 2011

The passage of ultrasonic sound through a fluid leads to pulsations of an entrained bubble that are so nonlinear that acoustic energy density is concentrated by 12 orders of magnitude to generate picosecond flashes of ultraviolet light. The spectrum, for xenon bubbles, matches an 8000 K ideal Planck blackbody even though the micron radius of the bubble is small compared to the photon mean free path. To probe the formation of a blackbody we have weakened sonoluminescence by generating it with a water hammer. The implosions are now subsonic and the collapse densities are only 1021/cc. Nevertheless, time resolved spectroscopy of these 1-s flashes indicates the formation of ideal blackbodies.
Where are the hot bubbles?
Authors: Kurz Thomas , Koch Philipp , Schanz Daniel , Lauterborn Werner
Published: July 2011

To contribute significantly, e.g., to sonoluminescence light emission, bubbles oscillating in an ultrasonic field have to persist for some time that is large compared to the acoustic driving period. This is the case if they are stable against perturbations of shape or position, and do not dissolve or grow too quickly by rectified diffusion. For noble-gas filled bubbles in water with parameters in the corresponding parameter region called bubble habitat, the peak temperatures at collapse are calculated using a standard ODE model of bubble dynamics, assuming homogeneous adiabatic compression of the gas-vapor mixture. Results are presented in terms of phase diagrams with the bubble’s rest radius, driving frequency, acoustic and static pressure, and gas concentration as control parameters. Hot bubbles are encountered in the giant response at high pressures and small bubble size. For such microbubbles, the assumption of homogeneity is tested by molecular dynamics simulations.
Single and multiple bubble shock-induced collapse: A computational study.
Authors: Hawker Nicholas , Betney Matthew , Ventikos Yiannis
Published: July 2011

We present computational simulations of shock-bubble interaction, leading to violent bubble collapse. Two-dimensional, axisymmetric and 3-D simulations of single and multiple bubbles, at various arrangements, are discussed. A front-tracking methodology (FronTier) is used to model accurately the liquid-gas surface, together with shock-capturing compressible methodologies for computing the shock propagation. A wide range of shock intensities is simulated (from 1 GPa, up to 100 GPa), and pressure, density, and temperature profiles are analyzed. The results obtained reveal a particularly complex behavior, even in the single bubble case, highly nonspherical, with a multitude of shock and contact structures emerging and interacting. Well-known phenomena, such as jet formation, are reproduced and parameterized. The subnanosecond and near-nanometer resolutions of the simulations reveal spatially and temporally discrete secondary collapse events and allow for the evaluation of conditions relevant to numerous processes and practical applications. The relative importance of conduction, viscosity, and surface tension are compared and discussed. Results obtained are juxtaposed to relevant available experimental data and features observed are discussed in the light of the finer resolution the computations offer.
Evaluating models of spectral density discrimination.
Authors: Stoelinga Christophe N. J. , Lutfi Robert A.
Published: July 2011

Spectral density, defined as the number of partials comprising a sound divided by its bandwidth, has been suggested as a cue for the identification of the size and shape of sound sources [Lutfi, Auditory Perception of Sound Sources (Springer-Verlag, New York, 2008), p. 23]. Two models have been proposed for the discrimination of spectral density. One assumes that the cue for discrimination is a change in the number of resolved partials, NRP [Stoelinga and Lutfi, Assoc. Res. Otolaryngology 31, 310 (2008)]. The other assumes that the cue is a change in the rate of power fluctuations in the sound, RPF [Hartmann et al., J. Acoust. Soc. Am. 79, 1915–1925 (1986)]. The two models were tested in separate experiments using a two-interval, forced-choice procedure for measuring spectral density discrimination. In the first experiment, NRP was varied from trial-to-trial, independently of spectral density, by clustering partials into unresolved groups. In the second experiment, RPF was varied from trial-to-trial by manipulating the relative phases of partials. The models were evaluated by comparing their analytic predictions for trial-by-trial responses in both experiments to obtained responses from human listeners. [Work supported by the NIDCD.]
Spatial influences on the spectral restoration of narrowband speech.
Authors: Cepeda Miguel , Best Virginia , Shinn-Cunningham Barbara
Published: July 2011

In phonemic restoration, both perceived continuity and intelligibility of temporally interrupted speech improve with the addition of noise in the speech gaps. Perceived continuity decreases slightly when interrupted speech and “filler” noise are presented from different directions; however, a recent study found that intelligibility is not strongly influenced by spatial cues. A few studies have demonstrated spectral restoration: improvements in the intelligibility of speech that has spectral notches when band-passed filler noise is added to the spectral gaps. Here, we explored whether the spatial location speech and filler noise influence intelligibility in spectral restoration conditions. We tested intelligibility of two 3/4-wide speech bands in a variety of configurations. Control conditions included diotic presentation of a low-frequency speech band alone, a high-frequency band alone, and the two bands together. Intelligibility was poor for either band alone, but significantly better with the two bands together. When we added diotic noise to the spectral gap between the low- and high-frequency bands, intelligibility improved. Finally, when we presented the noise with an ITD so that it was perceived from off center, intelligibility was lower than when both filler noise and speech bands were diotic. Results demonstrate a spatial influence on spectral restoration.
Relationship between basilar membrane compression estimates and masking release.
Authors: Gregan Melanie J. , Oxenham Andrew J. , Nelson Peggy B.
Published: July 2011

Listeners with cochlear hearing loss often obtain less benefit, or masking release (MR), than do normal-hearing listeners when a steady-state masker is replaced by a temporally fluctuating one, even when overall audibility differences between the two listener groups are taken into account. One possible explanation for the reduced MR seen in these listeners is loss of the active cochlear process that results in less compression and hence less amplification for speech segments that coincide with temporal gaps in the masker. This study tests whether varying degrees of cochlear compression can predict the degree of loss of MR. Behavioral estimates of compression, using temporal masking curves, were compared with the magnitude of MR for speech and for pure tones in a group of hearing-impaired listeners and a control group of age-matched noise-masked normal-hearing listeners. Compression estimates were made at 500, 1500, and 4000 Hz. Masking period patterns in a 10-Hz square-wave-gated speech-shaped noise were measured, as was MR for band-limited (500–4000-Hz) IEEE sentences, using the same temporally gated noise. The results will be used to test for a relationship between masking release and residual cochlear compression. [Work supported by NIH grants R01DC03909 and R01DC008306.]
Relative importance of temporal fine structure and spectral resolution on speech masking release.
Authors: Won Jong Ho , Park Minhyun , Rubinstein Jay T.
Published: July 2011

This study aimed to evaluate the relative importance of temporal fine structure (TFS) and spectral resolution on speech masking release. Speech perception abilities were measured with amplitude modulated noise and steady noise maskers in normal-hearing subjects. A vocoder processing technique was developed to systematically vary the amount of TFS delivered in stimuli: 0%, 50%, 75%, and 100% of TFS were presented. Spectral resolution was controlled by varying the number of vocoder channels: 8- and 32-channels were tested. Both TFS and spectral resolution were found to significantly contribute to speech perception in the two maskers. The addition of TFS information increased the speech masking release for 8- and 32-channel conditions, but the improvement was significantly greater for 8-channel condition. The results support the hypothesis that the effect of TFS on speech masking release will be greater when spectral resolution is limited. [Work supported by NIH Grants No. R01-DC007525 and T32-DC000033.]
The relationship between diotic and dichotic word recognition performance in young and older adults.
Authors: Roup Christina , Lamoreau Katie
Published: July 2011

A left-ear disadvantage for dichotic listening and a deficit in recognition of speech in a competing message have been described for older adults; however, few studies have reported performance on both measures in the same group of listeners. The purpose of the present study was to assess binaural word recognition abilities in competitive listening situations among young and older adults. Young adults (18–30 years) with normal hearing and older adults (60–90 years) with bilateral mild to severe sensorineural hearing loss participated. Word recognition performance was evaluated using NU-6 monosyllabic words presented in multitalker babble and dichotically. Psychometric functions across five signal-to-noise ratios were measured in three conditions: monaural right, monaural left, and diotic. Dichotic word recognition (DWR) was also measured in three conditions: free recall, directed-right, and directed-left. Results for the psychometric functions revealed better recognition performance in the diotic condition than for either monaural condition. Results for DWR indicated a mean right ear advantage for both the free recall and directed-right conditions, and a mean left ear advantage for the directed-left condition. Group data are consistent with a binaural advantage for speech recognition in competing listening conditions for both young and older adults. Individual differences will be discussed.
Interactions between hearing loss and the spectral overlap of competing sounds in masked speech intelligibility.
Authors: Best Virginia , Thompson Eric R. , Mason Christine R. , Kidd Gerald
Published: July 2011

This experiment explored the ideas that energetic masking (EM) limits the benefit achievable from spatial separation in a competing speech task and that differences in EM between normal-hearing (NH) and hearing-impaired (HI) listeners can explain differences in spatial release from masking (SRM). Target sentences and similar masker sentences (or in another condition, masker noises) were filtered into four narrow spectral bands and presented simultaneously. The spectral overlap of the target and masker bands was varied from minimal (interleaved bands) to maximal (identical bands). Both NH and HI listeners showed spectral tuning, such that masking by noise or speech was reduced as spectral overlap was reduced. In fact, this signal processing often improved intelligibility relative to that seen with unfiltered speech. Moreover, thresholds in the noise and speech maskers were closely related, suggesting that EM was the main factor limiting performance across tasks. More masking was found in HI as compared to NH listeners for all spectral overlaps and both maskers, and the HI group generally had less SRM. However, variations in spectral overlap did not lead to dramatic changes in SRM or in the difference in SRM observed between groups.
Spectrotemporal integration in listeners with normal hearing and those with noise-induced hearing loss.
Authors: Hoglund Evelyn M. , Oh YongHee , Feth Lawrence L.
Published: July 2011

The multiple looks model provides a reasonable explanation for temporal integration [Viemeister and Wakefield (1991)], and has been shown to hold for spectral integration as well [Grose and Hall (1997); Bacon et al., (2002)]. Prior results show that spectrotemporal integration of 1–8, 10-ms tone bursts in quiet are comparable for signals that change in frequency across time [Hoglund and Feth (2009)]. In this study, signals were extended (up to 12 tones) in both time and frequency. Thresholds were measured first in quiet and then with a pink masking noise. Consistent with other studies, results for normal hearing listeners in quiet or in noise exhibit integration functions with a shallower slope than predicted by an ideal listener. Listeners with noise-induced hearing loss (NIHL) were tested using the same conditions. Differences in integration performance are discussed for each set of conditions. Early results suggest that spectrotemporal integration may be more vulnerable to NIHL than either spectral- or temporal integration alone. [Research supported by a grant from the Office of Naval Research N000140911017.]
Level-dependent intelligibility of flat-spectrum speech.
Authors: Tabuchi Hisaaki , Sinex Donal G.
Published: July 2011

This study compared the intelligibility of speech after manipulations of amplitude- and phase-spectra similar to those reported by Kazama et al. [J. Acoust. Soc. Am. 127, 1432–1439 (2010)]. Two types of stimuli were used. (1) Randomized-phase speech (RPS) had the same amplitude-spectra as the unprocessed speech, but the original phases were replaced with randomized values. (2) Flat-spectrum speech (FSS) had the same phase-spectra as the unprocessed speech, but the original amplitudes were replaced with a constant amplitude. Each manipulation was carried out for time windows that varied from 0.25 to 1024 ms, and intelligibility was measured at 40, 55, and 70 dBA. For long window lengths (> 64–128 ms), the intelligibility for FSS was nearly perfect, but the intelligibility for RPS was lower than 90 % correct at 256–512 ms and decreased to chance performance at 1024 ms. For short window lengths (< 4–8 ms), the intelligibility for both FSS and RPS decreased. For intermediate window lengths (4–64 ms), the intelligibility for FSS was poor at 40 dBA and increased with level. Intelligibility for RPS did not vary with level. Nearly-perfect intelligibility was obtained at 4–8 and 64–128-ms time windows for both RPS and FSS. Non-linear properties are discussed. [Work supported by DC010615 to D.G.S.]
Remote frequency masking of a 4000 Hertz signal by a 500–1000 Hertz noise band.
Authors: Hillock-Dunn Andrea , Leibold Lori , Buss Emily
Published: July 2011

Werner and Bargones (1991) showed that infants are susceptible to remote-frequency masking of a 1 kHz tonal signal by a 4–10 kHz noise band, conditions for which adults do not experience masking. Differences in frequency selectivity with age cannot account for these findings, implicating informational masking. To further substantiate this interpretation and to assay whether such an effect is specific to high-frequency maskers, the current experiment compared the effects of a 500–501 kHz noise band on detection of a 4 kHz tone in 8–11 month-olds (n = 10) and adults (n = 9). A two-stage approach was employed whereby an adaptive procedure established the signal level needed to produce detection scores of 70.7% in quiet. That level was used in fixed conditions in quiet and in noise. These data were used to compute d-prime and estimate thresholds. Overall, infants’ thresholds were higher in noise than in quiet, whereas adults’ thresholds did not change across the two conditions. Results suggest that remote-frequency masking in infants occurs for maskers above or below the signal frequency.
Effect of signal-temporal uncertainty during childhood: Detection of a tonal signal in a random-frequency, two-tone masker.
Authors: Bonino Angela Y. , Leibold Lori J. , Buss Emily
Published: July 2011

The purpose of this study was to determine if listeners benefit from a cue indicating when in time a signal occurs. In order to examine age-related differences in performance, three groups of children (5–7, 8–10, and 11–13 year-olds) and adults were tested. Thresholds were measured for a 120-ms, 1000-Hz signal presented in a continuous random-frequency, two-tone masker presented at 50 dB SPL. Each 120-ms masker burst was composed of a pair of tones, one selected from a uniform distribution 300–920 Hz and the other from 1080–3000 Hz. This masker was selected because it is expected to produce primarily informational masking. Listeners completed two temporal conditions: (1) temporally-defined, with the signal embedded in a 600-ms light cue and (2) temporally-uncertain, with no light cue. Two phases of testing were completed for each temporal condition. For phase 1, a single-interval, adaptive track procedure determined the midpoint of the psychometric function. In phase 2, signal levels around the midpoint were tested using a single-interval method of constant stimuli procedure. For both temporal conditions, listeners completed four runs of 40 trials, with an equal signal-nonsignal probability. Results indicate a substantial release from masking with reduced signal-temporal uncertainty for both children and adults.
Infants’ responses to spectral and temporal degradations of speech signals.
Authors: Cabrera Laurianne , Bertoncini Josiane , Lorenzi Christian
Published: July 2011

The present study assessed the ability of 6-month-old infants with normal hearing (NH) to discriminate between voiced and unvoiced stop consonants (/aba/versus/apa/) using vocoded disyllables and the head-turn preference procedure. The disyllables were processed by 4- or 32-band noise-excited vocoders in order to (i) degrade temporal fine structure (TFS) cues while preserving spectral- and temporal-envelope cues, (ii) degrade TFS and temporal-envelope cues (temporal envelopes being lowpass filtered at 16 Hz in each frequency band), and (iii) degrade TFS and spectral-envelope cues (temporal-envelope cues being preserved in four broad frequency bands). Overall, the results showed that infants are able to discriminate voicing in each experimental condition. These findings suggest that as adults, 6-month-old infants require minimal spectral information to achieve robust speech discrimination as long as slow (<16 Hz) temporal-envelope cues are available in a few spectral regions. These findings also suggest that the impoverished spectral and temporal cues delivered by current cochlear implants processors can be used by 6-month-old infants to discriminate speech sounds.
Responses of neurons in the inferior colliculus of the awake rabbit to iterated rippled noise and harmonic tone complexes.
Authors: Flynn Brian C , Carney Laurel H.
Published: July 2011

The perception of pitch involves complex processing of acoustical signals, requiring the grouping of widely separated frequency components into a coherent sound object. Where and how pitch processing occurs in the auditory system is currently unknown. Fully characterizing the response of neurons in the nuclei of the ascending auditory pathway is an important first step in understanding the mechanism of pitch perception. While the responses of neurons in the auditory nerve and cochlear nucleus to pitch stimuli have previously been explored, the responses of neurons in the inferior colliculus have not been characterized. The inferior colliculus exhibits properties that make it a candidate for a pitch processing center, including converging input from nearly all lower auditory nuclei and bandpass tuning to amplitude modulation. Responses of inferior colliculus neurons to pitch stimuli are heterogeneous; however, interval histograms from some units in the inferior colliculus reveal locking to the dominant periods of complex stimuli such as iterated rippled noise and harmonic tone complexes. Characteristic responses of inferior colliculus neurons will be presented and implications for pitch processing in the inferior colliculus will be discussed. [Work supported by NIH-NIDCD RO1DC01641 and T32DC009974.]
Pitch perception and frequency-following response in inharmonic signals.
Authors: Aiken Steven J. , LeClair Kevin , Kiefte Michael
Published: July 2011

It has been suggested that auditory-evoked frequency-following response (FFR) is related to pitch [Greenberg et al., Hear. Res. 25, 91–114 (1987)], which is usually related to fundamental frequency of complex sounds. We examined FFR to dual-tone multi-frequency (DTMF) signals used in telephone communication. As these tones have been used to produce melodies, it was expected that they would have a measurable pitch and this was also determined in a behavioral task. Twelve subjects matched perceived pitch of DTMF signals to a pure tone via method of adjustment. In addition, the FFR to the same signals was recorded from the same subjects to establish whether significant FFR energy was present at the frequency of the perceived pitch. Correlation analysis of data from the behavioral task showed wide variation among subjects, with many identifying the perceived pitch as matching the lower of the two partials. Significant FFR energy was detected at both partials, which does not clarify the relationship between perceived pitch and the evoked response. In addition, we show that perceived pitch is highly context dependent and present data from FFR to stimuli in melodic contexts.
Spectral processing does not give rise to behaviorally relevant cues for “pitch” perception in mammals.
Authors: Shofner William P. , Chaney Megan
Published: July 2011

Mechanisms giving rise to pitch reflect spectral or temporal processing is still equivocal, because sounds having strong harmonic structures also have strong temporal structures. When a harmonic tone complex is passed through a noise vocoder, the resulting sound can have a harmonic structure with large peak-to-valley ratios, but little or no temporal structure. To test the role of harmonic structure in mammals, we measured behavioral responses to vocoded tone complexes in chinchillas using a stimulus generalization paradigm. Animals discriminated a harmonic tone complex from a one-channel vocoded version of the complex. When tested with vocoded versions generated with 8–128 channels, animals generalized to the one-channel version and showed no gradient in their behavioral responses. This suggests that spectral structure was not the cue for the behavioral response. To further test this, chinchillas discriminated an iterated rippled noise from the one-channel vocoded tone complex. When tested using vocoded tone complexes having harmonic peak-to-valley ratios that were larger than or similar to the rippled noise, animals again generalized to the 1-channel version rather than the to rippled noise. The results suggest that mammalian “pitch” attributes arise through temporal, not spectral, processing mechanisms. [Work supported by NIDCD R01 DC005596.]
Effects of contralateral acoustic stimulation on hearing threshold fine structure and spontaneous otoacoustic emissions.
Authors: Dewey James B. , Lee Jungmee , Dhar Sumitrajit
Published: July 2011

When plotted with fine frequency resolution, pure-tone thresholds often exhibit fine structure, a regular pattern of alternating minima and maxima. Spontaneous otoacoustic emissions (SOAEs) commonly occur at frequencies near those of threshold minima, and both phenomena are suggested to depend on active and vulnerable cochlear processes. The present study utilized contralateral acoustic stimulation (CAS), which modulates these processes via the medial olivocochlear efferent system, to further explore the relationship among SOAEs, threshold fine structure, and cochlear status. In normal-hearing individuals, thresholds and SOAEs were measured in quiet and with a 60 dB SPL broadband (0.1–10 kHz) noise presented to the contralateral ear. Thresholds were obtained in 1/500th–1/100th-octave steps at frequencies both near and far from those of SOAEs. Consistent with previous reports, CAS elevated SOAE frequency and reduced SOAE level. Threshold fine structure patterns were also shifted upward in frequency, though little reduction in the presence or depth of fine structure was observed. For frequency regions far from SOAEs, CAS elevated thresholds. However, at frequencies near SOAEs, where fine structure was more pronounced, thresholds often improved with CAS. Analysis of the relationships between concurrent changes in SOAE and thresholds will be presented.
Modeling the antimasking effects of the olivocochlear reflex in auditory-nerve responses to tones in noise.
Authors: Chintanpalli Ananthakrishna , Jennings Skyler G. , Heinz Michael G. , Strickland Elizabeth A.
Published: July 2011

The medial olivocochlear reflex (MOCR) has been hypothesized to provide benefit for listening in noise. The present study modeled antimasking effects in single auditory-nerve (AN) fibers [Kawase et al., J. Neurophysiol. 70, 2533–2549 (1993)]. A well-established computational model for normal-hearing and hearing-impaired AN responses [Zilany and Bruce, J. Acoust. Soc. Am. 120, 1446–1466 (2006)] was extended by using reductions in outer-hair-cell (OHC) gain to mimic the MOCR. Tone responses in noise were examined as a function of tone and noise level and OHC gain reduction. Signal detection theory was used to predict detection and discrimination for different spontaneous-rate fibers. Model results were consistent with physiological data. Decreasing OHC gain decreased the noise response and increased maximum firing rate to the tone, thus modeling the MOCR ability to decompress AN-fiber dynamic range (particularly high-spontaneous-rate fibers). For each masker level, an optimal OHC gain reduction (i.e., maximum discrimination without increased detection threshold) was found to be physiologically realistic. Thus, OHC gain reduction improved tone-in-noise discrimination even though it produced a “hearing loss” in quiet. Combining MOCR effects with the sensorineural-hearing-loss effects already captured by this AN model will be beneficial for exploring implications of their interaction for listening in noisy situations. [Work supported by NIH Grant No. R01-DC008327.]
Evaluating the effects of efferent feedback, temporal integration, and off-frequency listening on perceptual estimates of frequency selectivity.
Authors: Jennings Skyler G. , Strickland Elizabeth A.
Published: July 2011

A computational model was used to predict detection thresholds in two forward masking tasks used to estimate frequency selectivity. Tasks simulated involved obtaining psychophysical tuning curves and notch-noise tuning characteristics. These simulations were obtained for a series of signal levels ranging from 20–90 dB SPL and for three masking conditions. Short (20 ms) and long (120 ms) maskers were used in the first and second masking conditions, respectively. The third masking condition was identical to the first, except an additional sinusoid (called a “precursor”) preceded the masker. The precursor and long masker were assumed to reduce cochlear gain during the time window in which the signal was detected. Conversely, the short masker was assumed to have no effect on cochlear gain during the presentation of the signal. Several variables related to frequency selectivity were evaluated to determine their influence on estimated filter sharpness, filter high-side/low-side slopes, and filter best frequency. These variables included (1) gain reduction via the medial olivocochlear reflex, (2) temporal integration, and (3) off-frequency listening. Model predictions are compared to psychophysical data, and the influence of the aforementioned variables is discussed.
Enhancing the intelligibility of high-intensity speech: Evidence of inhibition in the lower auditory pathway.
Authors: Bashford James A. , Warren Richard M. , Lenz Peter W.
Published: July 2011

Intelligibility of narrowband speech declines considerably at high intensities, but substantial recovery from this “rollover” occurs when flanking noise bands are added. The present study employed two types of added noise: narrowband noise matching the spectral limits of the rectangular speech band (producing within-band masking) versus broadband noise (producing within-band masking plus simultaneous enhancement by out-of-band noise components). When noise added to diotic speech in experiment 1 was interaurally uncorrelated rather than diotic, intelligibility increased 5%, regardless of noise bandwidth. Interestingly, regardless of interaural correlation, intelligibility was about 13% higher with broadband rather than narrowband noise, indicating that noise-induced recovery from rollover precedes binaural processing. In experiment 2, diotic noise was presented either continuously or gated on and off with individual sentences. Intelligibility was 6% higher with continuous noise, showing adaptation of masking, which occurred regardless of noise bandwidth. Moreover, intelligibility was about 11% higher with broadband rather than narrowband noise, regardless of gating, ruling out peripheral adaptation as a source of recovery from rollover. These and other findings to be discussed are consistent with previous suggestions that intelligibility at high intensities is preserved by inhibition of rate-saturated auditory-nerve input to secondary neurons of the cochlear nucleus. [Work supported by NIH.]
Accurate estimation of the temporal dynamics of bouncing events.
Authors: Giordano Bruno L. , Shafiro Valeriy , Kharkhurin Anatoliy
Published: July 2011

The sound of a bouncing object is rich in dynamic acoustical information: subsequent bounces are more tightly spaced in time, have lower energy, and tend to excite less strongly the high-frequency resonant modes of the bounced-upon object. Previous studies on bouncing events show that dynamic information is not used to perceive the properties of the bouncing object. We tested whether this is the case when listeners are asked to predict the dynamic behavior of a bouncing event. Stimuli were recorded by dropping one of four different balls from various heights onto a hard linoleum surface. After hearing two, three, four, or five bounces, participants pressed a button to estimate the temporal location of the next bounce. No performance feedback was given. Participants never heard the bounce whose temporal location they were estimating. Bounce-time estimates were very accurate (r = 0.96). Acoustic analyzes revealed a strong focus on timing information and a secondary reliance on energetic information. Spectral information appeared to have negligible effects. These findings demonstrate the extreme versatility of human listeners in using variable acoustic cues to determine the dynamic behavior of real-world objects.
The utility of content-free acoustic analyzes for assessing prosodic disorder in children.
Authors: Redford Melissa A. , Cornell-Fabiano Jolynn
Published: July 2011

Global rhythm metrics have advanced our understanding of perceptually salient language rhythms and have proved useful for understanding perceptions of foreign accent. The metrics have also helped further the development of automated acoustic analyzes of speech, which are being applied to the clinical problems of early and differential diagnoses of speech and language disorder. This talk will consider the utility of such metrics for the assessment and treatment of children with disordered prosody. Results from an investigation of acoustic factors that contribute to the perception of disordered prosody in 24 school-age children suggest that global, content-free metrics of rhythm and intonation may be relatively poor predictors of experienced listeners’ perceptions of disorder in individual children though the metrics correlate with listeners’ differentiation of children with typical and atypical language development and of children with different eligibilities for speech and language services. Content-dependent acoustic analyzes more accurately account for the variability in judgments across children within particular groups. These results will be used to advocate for research that is aimed at acoustically characterizing prosodic disorder in individual children and at discovering the perceptual weightings and social significance of the acoustic correlates of disordered prosody. [Work supported by NICHD/NIH.]
Automatic acoustic-phonetic analyzes of thousands of hours of conversational speech in hard of hearing children.
Authors: VanDam Mark
Published: July 2011

The current longitudinal project examines speech and language development in 40 preschool children with mild- to severe-hearing loss (and a cohort of typically developing peers) as part of large, multicenter project on outcomes of children with hearing loss. Whole-day recordings are collected once monthly for 1 year and subjected to detailed acoustic-phonetic analyzes. To date, we have collected several hundred whole-day recordings using a commercially available, body-worn recorder and software (the LENA Foundation). The software performs unsupervised, offline analysis of the audio and produces (1) a time-aligned, XML-coded output including the talker labels adult-female, adult-male, target-child, and other-child and (2) the PCM wave file of the entire day. Audio segments of specific talkers are then extracted with custom software designed for detailed acoustic-phonetic analyzes of speech. For example, fundamental frequency was extracted for target-child utterances and compared in varied conversational exchanges with different interlocutors. This technology is suited to examine large-scale natural speech and langauge corpora. Developmental changes can be examined in domains ranging from prosody to conversational use of speech. Details of this research project, including advantages and challenges, will be discussed as well as theoretical implications for phonology and phonetics of child speech development. [Work supported by: NIH/NIDCD 5R01-DC009560-01S1.]
Emerging lexical representations in early infancy.
Authors: Lacerda Francisco
Published: July 2011

This presentation proposes the view that typical early infant-directed speech (IDS) in the infant’s ecological setting provides enough multisensory information to trigger the emergence of lexical representations, a theoretical view inspired by analyzes of the care-givers’ speech toward infants at different developmental stages. It will be argued that the adult’s speaking style in early IDS within the context of the infants’ immediate ecological setting provides enough correlated sensory information to derive potentially relevant lexical items from the stream of speech sounds and objects to which the infant is exposed. The proposed theoretical model of early language development [ecological theory of language acquisition (ETLA)] is supported both by experimental results indicating that 40 Swedish infants, in the age ranges 8–10 and 14–16 months, could infer object names from looking at 1-min video materials where objects were shown and described by natural utterances produced in languages unknown to the infants, and by mathematical simulations of how early lexical items can be derived from typical infant-directed speech handled by the infant’s general-purpose multisensory (audio-visual) representation capabilities. [Work supported by grant from The Bank of Sweden Tercentenary Foundation (Grant No. K2003:0867, MILLE), EU-NEST (Project No. 5010, CONTACT), Knut and Alice Wallenberg Foundation (Grant No. KAW2005.0115), and Stockholm University.
Modal tracking in a shallow ocean: An adaptive particle filtering approach.
Authors: Candy James V
Published: July 2011

It is well-known that the shallow ocean is an ever changing, uncertain environment dominated by temperature fluctuations and ambient noise. The need for a processor that can adapt to these environmental changes while simultaneously tracking the evolution of modal functions is necessary for localization, inversion, and enhancement. An approach to this problem is made possible by developing a sequential Bayesian processor capable of providing a joint solution to both the modal function tracking (estimation) and environmental adaptivity problem. The posterior distribution required will contain multiple peaks and space-varying statistics requiring a sequential (nonstationary) Bayesian approach. The final design that evolves is a so-called particle filter. The particle filter is a sequential Markov chain Monte Carlo processor capable of providing reasonable performance for a multi-mode (probability distribution), space-varying problem. The tracking results are applied to synthesized pressure-field data from the actual experimental parameters. The tracking results are compared to that of the modern unscented Kalman tracker solution.
Tracking noise in noise.
Authors: Cohen Leon , Galleani Lorenzo
Published: July 2011

Very often one wants to track one type of noise embedded in another noise. In addition, the noises may be nonstationary. For example, suppose one wants to track in time and or space a reverberation type noise that is embedded in an background ambient noise. Many of the techniques that have been developed for deterministic signals do not work for such situations. We discuss various methods that have been developed to track noises and to separate noises and to estimate the parameters of non-stationary noises. We will show that a particular effect method to understand nonstationary noises is to study them in phase space. We give a number of examples.
Two-stage diver tracking in a high-clutter harbor environment.
Authors: Edelson Geoffrey S. , Egnor Dianne E. , Haney Philip J. , Edson Patrick , Stein Peter J.
Published: July 2011

One approach to detecting swimmers with active sonar is to deploy a larger number of relatively simple nodes and network them together. Instead of using a complex multi-element phased array with electronic beamforming, this system uses air-backed parabolic reflectors, each with an omni-directional transducer. To avoid performance degrading acoustic interactions, the available operating frequency band is managed at the channel level. The physical configuration of this sonar system presents challenges for tracking through and across beams, and between nodes. Swimmers can exhibit low target strength and the acoustic clutter fields can be dense and highly dynamic. To detect and track swimmers in this environment, we employ a windowed Hough-transform (HT) tracker at the beam level. The HT has received wide use for track initiation. However, because of the processing gain required to continually track a weak target in such a significant clutter field, the HT is used in this case to maintain as well as to initiate tracks. The single- and multi-node tracker is a Kalman-based, multi-object tracker capable of tracking any number of stationary, constant-velocity and/or maneuvering targets. The multi-node tracker receives fused observations as inputs and creates accurate estimates based on the target position, velocity, and acceleration.
Geoacoustic inversion in the Shallow Water 2006 shelfbreak region using sequential Bayesian filters.
Authors: Yardim Caglar , Gerstoft Peter , Hodgkiss William S.
Published: July 2011

Environmental parameters can have a large spatial variability in shelfbreak regions. In this paper, sequential Bayesian filtering, or particle filtering (PF), is used for tracking this variation. The PFs can operate in nonstationary dynamic ocean environments that affect acoustic data via complex, nonlinear equations and non-Gaussian probability density functions. PFs are used to process the data obtained during the Shallow Water 2006 (SW06) Experiment conducted on the New Jersey Continental Shelf. The PFs are first used to track the source and the stable environment with little spatial variation just northwest of the shelfbreak. The PFs track the environment using a smaller number of particles relative to conventional geoacoustic inversion methods that use successive independent inversions. Then the range-dependent shelfbreak region is analyzed and the PF methods are compared to conventional geoacoustic inversion techniques. [Work supported by the ONR.]
A “tracker within a tracker”: Tracking multiple marine mammals.
Authors: Nosal Eva-Marie
Published: July 2011

In some multiple marine mammal datasets, it is possible to separate animals by tracking slowly varying call features such as peak frequency and amplitude. Separating animals in this way can be a useful step toward tracking the spatial position of the animals. This talk discusses this “tracker within a tracker” approach to multiple-animal datasets. Details of both trackers and examples from application to real datasets will be presented. [Work supported by ONR and NSF].
Underwater navigation/tracking using a single transponder.
Authors: Yang T. C. , Schindall Jeff , Yang W.-B.
Published: July 2011

Underwater vehicle navigation and/or tracking are commonly done using several transponders forming either a long or a short base line. Transponders are deployed in advance and vehicle position is then determined by triangulation using acoustic travel time between the vehicle and transponders. Multiple transponders are expensive and inconvenient due to time required for deployment and surveying their positions. This paper presents methods to navigate/track a vehicle using only one transponder which can be dropped with its position known from GPS. One method to navigate is to estimate the range and bearing using travel time and beamforming if the vehicle is equipped with several receivers. The other method uses Doppler sensitive waveforms, such as m-sequence signals. Bearing is estimated using Doppler shift assuming that the vehicle knows its speed relative to the ground, and range is estimated by travel time as usual. Experimental data are presented to illustrate both methods. Errors are minimized using an extended Kalman filter. [Work supported by the Office of Naval Research.]
Tracking tomographic arrivals.
Authors: Dzieciuch Matthew
Published: July 2011

Ocean acoustic tomography records an acoustic pattern of peaks that is interpreted in terms of ray arrivals. Before peaks can be tracked in the time-evolving environment, they must be associated with the correct ray path. Scattering by range-dependent ocean structure is a complicating factor. Fine scale structure limits the time and bandwidth coherence of an arrival and thus a single peak per ray path becomes multiple fading peaks. Associating the peak data with the ray model is often done by hand, but this has two drawbacks. First, a human is required to look at the data precluding processing the data in situ. Second, there is no guarantee that the analysis is repeatable. To address these concerns, three popular methods from radar data processing, the nearest neighbor standard filter, the probabalistic data association filter, and Viterbi data association, are proposed to solve the automatic data association problem. The peak arrival time, angle, and amplitude are clues used to construct a scoring function based on the likelihood ratio. A Kalman filter is used to restrict the expected arrival pattern to shifts and stretching between transmissions. A comparison of these methods with actual tomographic data will be presented.