| 1994, 396, Session N3, Poster |
| Temporal aspects of two-tone suppression exhibited by auditory-nerve fibers of cats |
| *Y. Cai, C.D. Geisler (University of Wisconsin-Madison, Madison) |
| Discharge patterns of approximately 100 normally-sensitive auditory-nerve fibers were obtained in response to two tones, a characteristic-frequency (CF) tone and a "low-side" suppressor tone (i.e. when suppressor frequency < CF). The CF tone was presented at low intensities (< 30 dB above threshold). The suppressor frequency (fSUP), which varied from 50 to 2000 Hz, was harmonically related to CF.
The stimulation paradigm involved partially overlapping tones which produced three distinct stimulus conditions during each stimulus trial: CF-alone, two simultaneous tones, and suppressor-alone.
Period histograms using 1/fSUP as base were constructed from the responses obtained during each stimulus condition (75 trials).
When low-frequency suppressors (50-200 Hz) were used, it was found, that the phase of the point of maximum suppression led, on average, the vector phase of the suppressor-alone response by approximately 1/4 cycle.
When higher frequency suppressors were used, the phase lead increased somewhat, approaching 1/2 cycle.
These phase relationships are in only partial agreement with comparable data in the literature (e.g. Sachs and Hubbard, Hear. Res., 1981).
For any particular two-tone response, the maximum rate obtained at any instant during the suppressor-tone cycle seldom exceeded the rate obtained during CF-alone stimulation at the same intensity.
These amplitude and phase relationships will be compared with those produced by a recent model of two-tone suppression (Geisler, Hear. Res., 1992). |
| Supported by NIH, through grant NIDCD-DC00116
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Citation for this abstract:
Cai, Y. and C.D. Geisler (1994). Temporal aspects of two-tone suppression
exhibited by auditory-nerve fibers of cats. Assoc. Res. Otolaryngol.
Abstr., p.98.
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