4pPP6. Eighth-nerve responses to sideband-attenuated and center frequency phase-shifted three-tone complexes.

Session: Thursday Afternoon, December 5

Time: 3:15

Author: Michael F. Chronopoulos
Location: Parmly Hearing Inst. and Dept. of Psych., Loyola Univ., 6525 N. Sheridan Rd., Chicago, IL 60626


In a previous study [M. Chronopoulos and R. R. Fay, J. Acoust. Soc. Am. 99, 2583--2584 (1996)], it was shown that goldfish (Carassius auratus) perception of three-tone complexes with either reduced modulation depths or a phase shift introduced at the center frequency (CF) is independent of both fine structure and power spectra of the signals. Behavioral responses were accounted for by a single function of the signals' normalized fourth moment of the envelope (NFME). The current experiment investigated the neurophysiological correlate of the goldfish's auditory nerve fiber's (saccular fiber's) responses to previously measured behavior. Signals included a 100% sinusiodally amplitude-modulated (SAM), a 350-Hz tone modulated at 30 Hz, and three-tone complexes with reduced modulation depths (MD). Reduced MD were achieved by either attenuating the sidebands (320 and 380 Hz) or phase shifting the CF component (350 Hz). Period histograms of single auditory fibers' responses were calculated. The histograms showed phase locking of the neural response to the envelope of the stimulus. The NFME of the histograms were measured. The NFME of the response histograms declined as a function of increasing sideband attenuation and increasing phase shift. Similar to behavioral measurements, NFME declined as a single function of the NFME of signals. [Work supported by a NIDCD Program Project Grant.]

ASA 132nd meeting - Hawaii, December 1996