Insights into optimal phonemic compression from a computational model of the auditory periphery

Authors

  • Ian C. Bruce Department of Electrical & Computer Engineering; School of Biomedical Engineering, McMaster University, Hamilton, ON, L8S 4K1, Canada
  • Faheem Dinath School of Biomedical Engineering, McMaster University, Hamilton, ON, L8S 4K1, Canada
  • Timothy J. Zeyl Department of Electrical & Computer Engineering, McMaster University, Hamilton, ON, L8S 4K1, Canada

Abstract

Phonemic compression schemes for hearing aids have thus far been developed and evaluated based on perceptual criteria such as speech intelligibility, sound comfort, and loudness equalization. Finding compression parameters that optimize all of these perceptual metrics has proved difficult. The goal of this study was to nd optimal single-band gain adjustments based on the response of auditory-nerve bers to speech. Sentences from the TIMIT database were processed by either the NAL-R or the DSL ampli cation scheme, and deviations from these linear prescriptions were obtained by adjusting the overall gain from 40 dB below to 40 dB above the prescribed gains in 5 dB steps. Neural responses were obtained using the cat auditory-periphery model of Zilany and Bruce (2006, 2007). Sentences were analyzed on a phone by phone basis to nd the gain adjustment that minimized the difference in neural response to the amplified phone in the impaired model and the unampli ed phone in the normal model. The optimal gain adjustments were found to depend on whether the error metric included the spike timing information of the neural responses (i.e., a time resolution of several microseconds) or just the mean ring rates (i.e., a time resolution of several milliseconds). To optimize the mean ring rates, gain adjustments on the order of +10 dB were required above the prescribed linear gains in general. In contrast, gain adjustments on the order of 10 dB or more below the prescribed linear gains tended to optimize the responses including spike timing information. Wide dynamic range compression appears to be more bene cial in optimizing the spike timing information than the mean rate information. These results motivate the development of novel nonlinear amplification schemes that simultaneously optimize both spike-timing and mean-rate neural representations.

References

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Additional Files

Published

2007-12-15

How to Cite

Bruce, I. C., Dinath, F., & Zeyl, T. J. (2007). Insights into optimal phonemic compression from a computational model of the auditory periphery. Proceedings of the International Symposium on Auditory and Audiological Research, 1, 73–82. Retrieved from https://proceedings.isaar.eu/index.php/isaarproc/article/view/2007-07

Issue

Vol. 1 (2007): Auditory Signal Processing in Hearing Impaired Listeners

Section

2007/1. Auditory signal processing and perception

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