William S. Rhode

Professor (emeritus)
Ph.D., 1970, University of Wisconsin - Madison

Contact Information
Email: rhode@physiology.wisc.edu
(608) 262-7953 Phone
(608) 265-5512 Fax

Research Interests
Information processing in the auditory system
Cochlear mechanical studies using laser interferometry

Research interests focus on information processing in the auditory system using stimuli ranging from simple (pure-tones) to complex signals. Complex signals include speech signals. They are often first studied in behavioral paradigms by Professor Kluender in the department of Psychology with whom we collaborate on all matters of speech signals (http://psych.wisc.edu/kluender/sensrep.htm).

Morphological/physiological correlations are studied through intracellular labelling of single neurons and subsequent computer-aided neuronal reconstruction of cells studied physiologically at all levels of the auditory system. Electrophysiological recordings are made in the auditory nerve, cochlear nucleus and inferior colliculus of several species.

Cochlear mechanical measurements are crucial to understanding of many clinical and psychophysical phenomena. There are many ways to 'explain' cochlear mechanics that have little to do with actual physics of hearing when there is insufficient data to constrain interpretations.

A central goal of these studies is to provide the database for interpreting observations obtained from physiological studies of the cochlear nerve or from psychophysical studies from which data are subsequent to transformations engendered by the auditory periphery.

Most cochlear mechanical measurements have been made in the basal region of the cochlea while the apical region is where most human communication sounds are processed. Measurements will be made in both the apical and mid-frequency regions to provide direct observations of mechanics in this critical region using a displacement measuring laser interferometer. These measurements should settle whether cochlear amplification exists and decreases continuously from base to apex.

An outcome the compressive nonlinearity in cochlear mechanics is that the response to complex signals cannot be predicted based on pure-tone responses.

Proposed studies are designed to determine the representation of multi-tone and speech-like (two-formant) signal complexes in the base, middle and apical region of the cochlea.

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Figure (above): individual variation within the principal cells of the dorsal cochlear nucleus of cat.

Selected Publications

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• Coady, J.A., Kluender, K,R. and Rhode, W.S. (2003) Efects of contrast between onsets of speech and other complex spectra. J. Acoust. Soc. Am. 114:2225-2235.
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• Rhode, W.S. and Recio. A. (2002) Cochlear mechanical distortion for complex stimuli in the chinchilla basal region. In: The Biophysics of the Cochlea: Molecules to Models. Gummer, A. Ed
   
• Recio, A., Rhode, W.S., Kiefte, M., and Kluender, K. R. (2002) Responses to cochlear normalized speech stimuli in the auditory nerve of cat. J. Acoust. Soc. Am. 111:2213-2218
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• Kiefte, M., Kluender, K. R., and Rhode, W. S. (2002). "Synthetic speech stimuli spectrally normalized for nonhuman cochlear dimensions," ARLO 3, 41-46.
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• Rhode, W.S. and Recio, A. (2001) Multicomponent stimulus interactions observed in basilar membrane vibration in the basal region of the chinchilla cochlea. J. Acoust. Soc. Am. 110:3140-3154.
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• Rhode, W.S. and Recio, A. (2001) Basilar membrane response to multicomponent stimuli in chinchilla. J. Acoust. Soc. Am. 110: 981-994.
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• Recio, A. and Rhode, W.S. (2000) The representation of vowel stimuli in the ventral cochlear nucleus of the chinchilla. Hearing Research, 146:167-184.
   
• Recio, A. and Rhode, A. (2000) Basilar membrane responses to broadband stimuli. J. Acoust. Soc. Am. 108: 2281-2298.
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• Rhode, W.S. and Recio, A. (2000) Study of mechanical motions in the basal region of the chinchilla cochlea. J. Acoust. Soc. Am., 107: 3317-3332.
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• Rhode, W.S. (1999) Vertical cell responses to sound in cat dorsal cochlear nucleus. J. of Neurophysiology, 1019-1032.
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• Rhode, W.S. (1998) Neural encoding of single-formant stimuli in the cochlear nucleus of chinchilla. Hearing Research, 117:39-56.

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