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

3aPP16. Peak detection for auditory sound discrimination.

Julius L. Goldstein

Central Inst. for the Deaf, 818 S. Euclid, St. Louis, MO 63110-1594

Joseph L. Hall

AT&T Bell Labs., Murray Hill, NJ 07974-0636

Auditory detection of envelope maxima in temporal responses of cochlear frequency-analyzing filters has been hypothesized to account for phase effects in psychophysical discrimination [J. L. Goldstein, 458--479 (1967)]. Re-examination of this hypothesis in the context of asymmetry of masking [R. Hellman, Percept. Psychophys. 11, 241--246 (1972)] reveals that it also provides an adequate explanation for this phenomenon. Peak discrimination between a tone and tone masker plus narrow-band-noise probe is more sensitive to probe energy than is the inverse discrimination between noise and noise masker plus tone probe, in agreement with psychophysics. Simulations of this model indicate that asymmetry of masking is a function of the product of noise bandwidth and temporal duration. Psychophysical experiments on masking asymmetry were performed with both masker and probe bandwidth ranging from pure tone to supracritical band. The experimental design included both fixed and roving levels, with random phases fixed throughout each experiment. A standard detection-theory model was fit to the data, assuming that ratios of peaks or of normalized peaks are measured by an optimal noisy discriminator. Predictions based upon stimulus envelopes are in good agreement with the data.