• Volume/Page
  • Keyword
  • DOI
  • Citation
  • Advanced
   
 
 
 

Journal of the Acoustical Society of America

BROWSE VOLUMES

Year Range: 
Search Issue | RSS Feeds RSS
Next Issue

Jan 2000

Volume 107, Issue 1, pp. 1-L6

Return to All Sections
back to top
RSS Feeds

Correlated cortical populations can enhance sound localization performance

Rick L. Jenison

J. Acoust. Soc. Am. Volume 107, Issue 1, pp. 414-421 (2000); (8 pages) | Cited 1 time

Full Text: | Download PDF

Show Abstract
Neurons within cortical populations often evidence some degree of response correlation. Correlation has generally been regarded as detrimental to the decoding performance of a theoretical vector-averaging observer making inferences about the physical world—for example, an observer estimating the location of a sound source. However, if an alternative decoder is considered, in this case a Maximum Likelihood estimator, performance can improve when responses in the population are correlated. Improvement in sound localization performance is demonstrated analytically using Fisher information, and is also shown using Monte Carlo simulations based on recordings from single neurons in cat primary auditory cortex. © 2000 Acoustical Society of America.
Show PACS
43.64.Bt Models and theories of the auditory system
43.64.Qh Electrophysiology of the auditory central nervous system

Vibration characteristics of bone conducted sound in vitro

Stefan Stenfelt, Bo Håkansson, and Anders Tjellström

J. Acoust. Soc. Am. Volume 107, Issue 1, pp. 422-431 (2000); (10 pages) | Cited 9 times

Full Text: | Download PDF

Show Abstract
A dry skull added with damping material was used to investigate the vibratory pattern of bone conducted sound. Three orthogonal vibration responses of the cochleae were measured, by means of miniature accelerometers, in the frequency range 0.1–10 kHz. The exciter was attached to the temporal, parietal, and frontal bones, one at the time. In the transmission response to the ipsilateral cochlea, a profound low frequency antiresonance (attenuation) was found, verified psycho-acoustically, and shown to yield a distinct lateralization effect. It was also shown that, for the ipsilateral side, the direction of excitation coincides with that of maximum response. At the contralateral cochlea, no such dominating response direction was found for frequencies above the first skull resonance. An overall higher response level was achieved, for the total energy transmission in general and specifically for the direction of excitation, at the ipsilateral cochlea when the transducer was attached to the excitation point closest to the cochlea. The transranial attenuation was found to be frequency dependent, with values from −5 to 10 dB for the energy transmission and −30 to 40 dB for measurements in a single direction, with a tendency toward higher attenuation at the higher frequencies. © 2000 Acoustical Society of America.
Show PACS
43.64.Bt Models and theories of the auditory system
43.66.Ba Models and theories of auditory processes
43.66.Ts Auditory prostheses, hearing aids

A performance adequate computational model for auditory localization

Wing Chung, Simon Carlile, and Philip Leong

J. Acoust. Soc. Am. Volume 107, Issue 1, pp. 432-445 (2000); (14 pages) | Cited 5 times

Full Text: | Download PDF

Show Abstract
A computational model of auditory localization resulting in performance similar to humans is reported. The model incorporates both the monaural and binaural cues available to a human for sound localization. Essential elements used in the simulation of the processes of auditory cue generation and encoding by the nervous system include measured head-related transfer functions (HRTFs), minimum audible field (MAF), and the Patterson–Holdsworth cochlear model. A two-layer feed-forward back-propagation artificial neural network (ANN) was trained to transform the localization cues to a two-dimensional map that gives the direction of the sound source. The model results were compared with (i) the localization performance of the human listener who provided the HRTFs for the model and (ii) the localization performance of a group of 19 other human listeners. The localization accuracy and front–back confusion error rates exhibited by the model were similar to both the single listener and the group results. This suggests that the simulation of the cue generation and extraction processes as well as the model parameters were reasonable approximations to the overall biological processes. The amplitude resolution of the monaural spectral cues was varied and the influence on the model’s performance was determined. The model with 128 cochlear channels required an amplitude resolution of approximately 20 discrete levels for encoding the spectral cue to deliver similar localization performance to the group of human listeners. © 2000 Acoustical Society of America.
Show PACS
43.64.Bt Models and theories of the auditory system
43.64.Ha Acoustical properties of the outer ear; middle-ear mechanics and reflex
43.66.Qp Localization of sound sources

Distortion product otoacoustic emission (2f1-f2) amplitude growth in human adults and neonates

Carolina Abdala

J. Acoust. Soc. Am. Volume 107, Issue 1, pp. 446-456 (2000); (11 pages) | Cited 13 times

Full Text: | Download PDF

Show Abstract
Distortion product otoacoustic emissions (DPOAEs) are thought to be by-products of an active amplification process in the cochlea and thus serve as a metric for evaluating the integrity of this process. Because the cochlear amplifier functions in a level-dependent fashion, DPOAEs recorded as a function of stimulus level (i.e., a DPOAE growth function) may provide important information about the range and operational characteristics of the cochlear amplifier. The DPOAE growth functions recorded in human adults and neonates may provide information about the maturation of these active cochlear processes. Two experiments were conducted. Experiment I included normal-hearing adults and term-born neonates. The 2f1-f2 DPOAE growth functions were recorded for both age groups at three f2 frequencies. Experiment II was an extension of the first experiment but added a subject group of premature neonates. The results of these studies indicate that DPOAE growth functions most often show amplitude saturation and nonmonotonic growth for all age groups. However, premature neonates show monotonic growth and the absence of amplitude saturation more often than adults. Those premature neonates who do show saturation also show an elevated threshold for amplitude saturation relative to adults. In contrast, term neonates are adultlike for most measures except that they show a larger percentage of nonsaturating growth functions than adults. These results may indicate immaturity in cochlear amplifier function prior to term birth in humans. Outer hair cell function and/or efferent regulation of outer hair cell function are hypothesized sources of this immaturity, although some contribution from the immature middle ear cannot be ruled out. © 2000 Acoustical Society of America.
Show PACS
43.64.Jb Otoacoustic emissions
43.64.Kc Cochlear mechanics

Indications of different distortion product otoacoustic emission mechanisms from a detailed f1,f2 area study

Richard D. Knight and David T. Kemp

J. Acoust. Soc. Am. Volume 107, Issue 1, pp. 457-473 (2000); (17 pages) | Cited 45 times

Full Text: | Download PDF

Show Abstract
The primary site of generation on the basilar membrane for the 2 f1–f2 distortion product (DP) is generally considered to be near where the higher-frequency stimulus tone peaks. This site has also been shown to be a source of DP otoacoustic emission (DPOAE) in the ear canal, but a second source of emission is known to exist in the region of the DP frequency place. The DPOAE phase versus frequency gradient provides a means of investigating the emission mechanisms. “Wave-fixed” and “place-fixed” mechanisms have been proposed to account for the very different phase gradients found depending on whether the 2 f1–f2 DPOAE is evoked by a small or large stimulus-frequency ratio. DPOAE phase versus frequency gradients can be investigated either by sweeping f1,f2 or by sweeping both frequencies maintaining a constant frequency ratio. Each manipulation gives only a partial description of DP behavior. In this study, the place-fixed/wave-fixed dichotomy is analyzed using extensive 2 f1–f2 and 2 f2–f1 DP stimulus-frequency sweep data presented on matrices of f1 vs f2 and f2/f1 ratio versus DP frequency. These show how the DPs are related and provide a more complete picture of 2 f1–f2 and 2 f2–f1 DPOAE phase and amplitude versus frequency behavior. The phase data contain evidence for a systematic variation in the proportions of wave- and place-fixed emission. The results suggest that 2 f1–f2 DPOAEs with a wide stimulus frequency ratio are wave fixed, while all other DPOAEs are place fixed. A transition occurs within the 2 f1–f2 DP data region at a frequency ratio of about f2/f1 = 1.1. The 2 f1–f2 DP and 2 f2–f1 DP phase behavior is continuous across the f2/f1 = 1 boundary. As the 2 f2–f1 DP generation region must be strongly influenced by the DP frequency place, the results imply that the place-fixed component of the 2 f1–f2 DP is also linked to its frequency place. A similar pattern was obtained with the 3f1–2 f2 and 3f2–2 f1 DPs. The results support the following model: For the limited set of stimulus conditions that gives rise to 2 f1–f2 wave-fixed emissions, DP energy is largely generated in the f2 region and is emitted directly. All other DPOAEs are place-fixed emissions, and while nonlinearity within the f2 stimulus envelope remains the generator, the DP is not directly emitted but travels apically until it is re-emitted basally via a separate reflection mechanism in the region of the DP place. © 2000 Acoustical Society of America.
Show PACS
43.64.Jb Otoacoustic emissions
43.64.Kc Cochlear mechanics
43.64.Ri Evoked responses to sounds

Three-dimensional numerical modeling for global cochlear dynamics

Anand A. Parthasarathi, Karl Grosh, and Alfred L. Nuttall

J. Acoust. Soc. Am. Volume 107, Issue 1, pp. 474-485 (2000); (12 pages) | Cited 10 times

Full Text: | Download PDF

Show Abstract
A hybrid analytical-numerical model using Galerkin approximation to variational equations has been developed for predicting global cochlear responses. The formulation provides a flexible framework capable of incorporating morphologically based mechanical models of the cochlear partition and realistic geometry. The framework is applied for a simplified model with an emphasis on application of hybrid methods for three-dimensional modeling. The resulting formulation is modular, where matrices representing fluid and cochlear partition are constructed independently. Computational cost is reduced using two methods, a modal–finite-element method and a boundary element–finite-element method. The first uses a cross-mode expansion of fluid pressure (2.5D model) and the second uses a waveguide Green’s-function-based boundary element method (BEM). A novel wave number approach to the boundary element formulation for interior problem results in efficient computation of the finite-element matrix. For the two methods a convergence study is undertaken using a simplified passive structural model of cochlear partition. It is shown that basilar membrane velocity close to best place is influenced by fluid and structural discretization. Cochlear duct pressure fields are also shown demonstrating the 3D nature of pressure near best place. © 2000 Acoustical Society of America.
Show PACS
43.64.Kc Cochlear mechanics
43.64.Bt Models and theories of the auditory system

Neural responses to the onset of voicing are unrelated to other measures of temporal resolution

Donal G. Sinex and Guang-Di Chen

J. Acoust. Soc. Am. Volume 107, Issue 1, pp. 486-495 (2000); (10 pages)

Full Text: | Download PDF

Show Abstract
Voice onset time (VOT) is a temporal cue that can distinguish consonants such as /d/ from /t/. It has previously been shown that neurons’ responses to the onset of voicing are strongly dependent on their static spectral sensitivity. This study examined the relation between temporal resolution, determined from responses to sinusoidally amplitude-modulated (SAM) tones, and responses to syllables with different VOTs. Responses to syllables and SAM tones were obtained from low-frequency neurons in the inferior colliculus (IC) of the chinchilla. VOT and modulation period varied from 10 to 70 ms in 10-ms steps, and discharge rates elicited by stimuli whose amplitude envelopes were modulated over the same temporal interval were compared. Neurons that respond preferentially to syllables with particular VOTs might be expected to respond best to the SAM tones with comparable modulation periods. However, no consistent agreement between responses to VOT syllables and to SAM tones was obtained. These results confirm the previous suggestion that IC neurons’ selectivity for VOT is determined by spectral rather than temporal sensitivity. © 2000 Acoustical Society of America.
Show PACS
43.64.Qh Electrophysiology of the auditory central nervous system
43.64.Sj Neural responses to speech
43.64.Bt Models and theories of the auditory system

Vestibular responses to loud dance music: A physiological basis of the “rock and roll threshold”?

Neil P. McAngus Todd and Frederick W. Cody

J. Acoust. Soc. Am. Volume 107, Issue 1, pp. 496-500 (2000); (5 pages) | Cited 2 times

Full Text: | Download PDF

Show Abstract
In this paper new evidence is provided to indicate that vestibular responses may be obtained from loud dance music for intensities above 90 dB(A) SPL (Impulse-weighted). In a sample of ten subjects acoustically evoked EMG were obtained from the sternocleidomastoid muscle in response to a sample of techno music typical of that which may be experienced in a dance club. Previous research has shown that this response is vestibularly mediated since it can be obtained in subjects with loss of cochlear function, but is absent in subjects with loss of vestibular function (Colebatch et al. [J. Neurol. Neurosurg. Psychiatr. 57, 190–197 (1994)]. Given that pleasurable sensations of self-motion are widely sought after by more normal means of vestibular stimulation, it is suggested that acoustically evoked sensations of self-motion may account for the compulsion to exposure to loud music. Given further the similarity between the thresholds found, and the intensities and frequency distributions that are typical in rock concerts and dance clubs, it is also suggested that this response may be a physiological basis for the minimum loudness necessary for rock and dance music to work—the “rock and roll threshold” [Dibble, J. Audio Eng. Soc. 43(4), 251–266 (1995)]. © 2000 Acoustical Society of America.
Show PACS
43.64.Ri Evoked responses to sounds
43.66.Lj Perceptual effects of sound
Return to All Sections
Close

Home Publications Meetings Contact ASA Site Map Back to Top

Copyright © Acoustical Society of America

close