### ASA 129th Meeting - Washington, DC - 1995 May 30 .. Jun 06

## 3aPP1. Pitch and pitch strength of iterated rippled noise.

**William A. Yost
**

**
Sandra J. Guzman
**

**
Stanley Sheft
**

**
**
*Parmly Hear. Inst., Loyola Univ. Chicago, 6525 N. Sheridan Rd., Chicago,
IL 60626
*

*
*
A cascade of add, delay (d ms), and attenuate (-1(less than or equal
to)g(less than or equal to)1) circuit excited with noise produces iterated
rippled noise (IRN) stimuli. The matched pitch and discriminability between
pairs of IRN stimuli were studied as a function of g, d, and the number of
circuit iterations (n). For g>0, the pitch of all IRN stimuli equals 1/d. For
g<0, pitch depends on n: For small n, there were two pitches in the region of
1/d, while for large n there was a single pitch equal to 1/2d. Peaks in the
autocorrelation function of IRN stimuli accounted for all of the results. Peaks
in the autocorrelation functions for IRN stimuli indicate the number of
intervals in the waveform with durations pd (p=1,2,...,n), and for g<0
intervals related to peaks near 1/md (m=odd integers) caused by assumed
auditory filtering. The number of intervals (i.e., the heights of the
autocorrelation peaks) determines the discriminability between IRN stimuli,
while the reciprocal of the interval duration determines the matched pitch.
These results support a temporal rather than a spectral account of the pitch of
IRN stimuli. [Work supported by NIH.]