Physiological and psychophysical assessments of the dynamic range of vowel representations in the auditory periphery

  • Authors:
  • Bradford J. May

  • Affiliations:
  • Department of Otolaryngology-HNS, Johns Hopkins University, 505 Traylor Research Building, 720 Rutland Avenue, Baltimore, MD

  • Venue:
  • Speech Communication - Special issue on the nature of speech perception (the psychophysics of speech perception III)
  • Year:
  • 2003

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Abstract

This review summarizes our work on the neural encoding of steady-state vowels. As in previous studies from our laboratory, the speech code is described in terms of average discharge rates for populations of neurons in the auditory nerve and ventral cochlear nucleus of barbiturate anesthetized cats. Our current analyses extend these population measures with new statistical models and signal detection methods to facilitate quantitative comparisons of the effects of stimulus level on vowel formant representations. These measures are applied to low and high spontaneous rate auditory-nerve fibers, and four of the principal response types of the ventral cochlear nucleus. The perceptual significance of the speech code is examined by relating neural response patterns to the behavioral performance of cats in vowel formant discrimination tasks. In combination, these physiological and psychophysical assessments suggest that vowel-coding mechanisms based on discharge rates in the auditory periphery are sufficient to support the dynamic range of speech perception.