A new model for calculating auditory excitation patterns and loudness for cases of cochlear hearing loss (original) (raw)
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Further evaluation of a model of loudness perception applied to cochlear hearing loss
Journal of The Acoustical Society of America, 1999
This paper describes further tests of a model for loudness perception in people with cochlear hearing loss. It is assumed that the hearing loss ͑the elevation in absolute threshold͒ at each audiometric frequency can be partitioned into a loss due to damage to outer hair cells ͑OHCs͒ and a loss due to damage to inner hair cells ͑IHCs͒ and/or neurons. The former affects primarily the active mechanism that amplifies the basilar membrane ͑BM͒ response to weak sounds. It is modeled by increasing the excitation level required for threshold, which results in a steeper growth of specific loudness with increasing excitation level. Loss of frequency selectivity, which results in broader excitation patterns, is also assumed to be directly related to the OHC loss. IHC damage is modeled by an attenuation of the calculated excitation level at each frequency. The model also allows for the possibility of complete loss of IHCs or functional neurons at certain places within the cochlea ͑''dead'' regions͒. The parameters of the model ͑OHC loss at each audiometric frequency, plus frequency limits of the dead regions͒ were determined for three subjects with unilateral cochlear hearing loss, using data on loudness matches between sinusoids presented alternately to their two ears. Further experiments used bands of noise that were either 1-equivalent rectangular bandwidth ͑ERB͒ wide or 6-ERBs wide, centered at 1 kHz. Subjects made loudness matches for these bands of noise both within ears and across ears. The model was reasonably accurate in predicting the results of these matches without any further adjustment of the parameters.
A new method of calculating auditory excitation patterns and loudness for steady sounds
Hearing Research, 2011
A new method for calculating auditory excitation patterns and loudness for steady sounds is described. The method is based on a nonlinear filterbank in which each filter is the sum of a broad passive filter and a sharp active filter. All filters have a rounded-exponential shape. For each center frequency (CF), the gain of the active filter is controlled by the output of the passive filter. The parameters of the model were derived from large sets of previously published notched-noise masking data obtained from human subjects. Excitation patterns derived using the new filterbank include the effects of basilar membrane compression. Loudness can be calculated as the area under the excitation pattern when plotted in intensity-like units on an ERB N -number (Cam) scale; no transformation from excitation to specific loudness is required. The method predicts the standard equal-loudness contours and loudness as a function of bandwidth with good accuracy. With some additional assumptions, the method also gives reasonably accurate predictions of partial loudness.
A comparative study of seven human cochlear filter models
Auditory models have been developed for decades to simulate characteristics of the human auditory system, but it is often unknown how well auditory models compare to each other or perform in tasks they were not primarily designed for. This study systematically analyzes predictions of seven publicly-available cochlear filter models in response to a fixed set of stimuli to assess their capabilities of reproducing key aspects of human cochlear mechanics. The following features were assessed at frequencies of 0.5, 1, 2, 4, and 8 kHz: cochlear excitation patterns, nonlinear response growth, frequency selectivity, group delays, signal-in-noise processing, and amplitude modulation representation. For each task, the simulations were compared to available physiological data recorded in guinea pigs and gerbils as well as to human psychoacoustics data. The presented results provide application-oriented users with comprehensive information on the advantages, limitations and computation costs of these seven mainstream cochlear filter models.
Individual Hearing Loss: Characterization, Modelling, Compensation Strategies
Trends in hearing, 2016
It is well-established that hearing loss does not only lead to a reduction of hearing sensitivity. Large individual differences are typically observed among listeners with hearing impairment in a wide range of suprathreshold auditory measures. In many cases, audiometric thresholds cannot fully account for such individual differences, which make it challenging to find adequate compensation strategies in hearing devices. How to characterize, model, and compensate for individual hearing loss were the main topics of the fifth International Symposium on Auditory and Audiological Research (ISAAR), held in Nyborg, Denmark, in August 2015. The following collection of papers results from some of the work that was presented and discussed at the symposium.
Ear and Hearing, 1991
A theoretical criterion for preliminary prescription of hearing aid gain and frequency response was formulated on the basis of Zwicker's loudness model, modified for impaired auditory frequency resolution in cochlear hearing losses. The procedure was designed to restore normal relative loudness contributions from each frequency band of input speech. Prescribed frequency responses had less steep bass cut than recommended by either the Prescription of Gain/Output or the National Acoustic Laboratories' procedures, regardless of various model assumptions. Prescribed overall gain depended on the loudness growth assumed in the model. In cases where auditory filters are wider than normal and loudness recruitment is complete, the procedure yielded a nonlinear relation between hearing aid gain and hearing loss: Required insertion gain (in dB) was 25 to 30% of hearing threshold loss (in dB HL) for mild to moderate losses, but this percentage increased for more severe impairments. For cases with incomplete loudness recruitment, the model prescribed that insertion gain should be 40 to 50% of hearing threshold loss for a wide range of impairments (Ear Hear 12 4:242-250).
Auditory-filter characteristics for listeners with real and simulated hearing impairment
Trends in amplification, 2012
Functional simulation of sensorineural hearing impairment is an important research tool that can elucidate the nature of hearing impairments and suggest or eliminate compensatory signal-processing schemes. The objective of the current study was to evaluate the capability of an audibility-based functional simulation of hearing loss to reproduce the auditory-filter characteristics of listeners with sensorineural hearing loss. The hearing-loss simulation used either threshold-elevating noise alone or a combination of threshold-elevating noise and multiband expansion to reproduce the audibility-based characteristics of the loss (including detection thresholds, dynamic range, and loudness recruitment). The hearing losses of 10 listeners with bilateral, mild-to-severe hearing loss were simulated in 10 corresponding groups of 3 age-matched normal-hearing listeners. Frequency selectivity was measured using a notched-noise masking paradigm at five probe frequencies in the range of 250 to 400...
Cochlear Model for Hearing Loss
Update On Hearing Loss, 2015
In many psychoacoustical tasks, hearing-impaired subjects display abnormal audiograms and poor understanding of speech compared to normal listeners. Existing models that explain the performance of the hearing impaired indicate that possible sources for cochlear hearing loss may be the dysfunction of the outer and inner hair cells. In this study, a model of the auditory system is introduced. It includes two stages: (1) a nonlinear time domain cochlear model with active outer hair cells that are driven by the tectorial membrane motion and (2) a synaptic model that generates the auditory nerve instantaneous rate as a response to the basilar membrane motion and is affected by the inner hair cell transduction efficiency. The model can fit both a normal auditory system and an abnormal auditory system with easily induced pathologies. In typical psychoacoustical detection experiments, the ability of subjects to perceive a minimum difference in a physical property is measured. We use the model presented here to predict these performances by assuming that the brain behaves as an optimal processor that estimates a particular physical parameter. The performance of the optimal processor is derived by calculating its lower bound. Since neural activity is described as a nonhomogeneous Poisson process whose instantaneous rate was derived, the Cramer-Rao lower bound can be analytically obtained for both rate coding and all information coding. We compared the model predictions of normal and abnormal cochleae to human thresholds of pure tones in quiet and in the presence of background noise.
Hearing Research, 2001
For normal listeners, difference limens for intensity (DLs) for Gaussian-shaped tone pulses are largest at medium pulse durations (corresponding to about five cycles of the tonal carrier) when the pedestals are 10 dB above threshold, either in quiet or in a pink noise background. One explanation for this is that worst performance occurs when the internal representation of the tone pulses is most compact in time and frequency, affording minimal opportunity for`multiple looks' (Van Schijndel et al., J. Acoust. Soc. Am. 105 (1999) 3425^3435). However, the mid-duration worsening is largest for medium overall levels, suggesting an involvement of compression on the basilar membrane (BM), which is also greatest at medium levels (Baer et al., J. Acoust. Soc. Am. 106 (1999. If this is so, the mid-duration worsening should be reduced when BM compression is reduced by outer hair cell damage. To test this, subjects with sensorineural hearing losses were tested using 1-kHz or 4-kHz Gaussian-shaped tone pulses, in quiet or in pink noise that raised thresholds by 10^20 dB. For subjects with mild losses, poorest performance was sometimes found for medium durations. For more severe losses, intensity DLs tended to improve monotonically or remain roughly constant with increasing duration. Performance overall tended to be better for subjects with greater hearing losses. The results are more consistent with an explanation based on BM compression than with an explanation based on multiple looks. ß 2001 Elsevier Science B.V. All rights reserved. frequency; DL, di¡erence limen for intensity; ERB, equivalent rectangular bandwidth of the auditory ¢lter; HL OHC , component of hearing loss due to outer hair cell damage; IHC, inner hair cell Hearing Research 159 www.elsevier.com/locate/heares