ASA 127th Meeting M.I.T. 1994 June 6-10

5aPP15. Temporal asynchrony effects in listeners with cochlear hearing loss.

J. H. Grose

J. W. Hall

L. Mendoza

Div. Otolaryngol./Head & Neck Surgery, Univ. North Carolina at Chapel Hill, Chapel Hill, NC 27599-7070

Temporal asynchrony appears to play a dominant role in the perceptual organization of multi-source sounds. Two paradigms in which temporal asynchrony results in perceptual segregation are comodulation masking release (CMR) and modulation detection interference (MDI). Both of these paradigms involve amplitude-modulated stimuli. Because listeners with hearing loss of cochlear origin often exhibit reduced temporal resolution for modulated stimuli, this study examined whether these listeners are as susceptible to asynchrony effects as are listeners with normal hearing. The CMR task was similar to one described previously [J. H. Grose and J. W. Hall, J. Acoust. Soc. Am. 93, 2896--2902 (1993)]. The modulation interference task was novel. The baseline condition was a measure of sequention envelope discrimination for a 20-Hz wide band of noise centered at 1125 Hz. Modulation interference was measured as a reduction in performance brought about by the synchronous presentation of a second independent band of noise centered at 3784 Hz. The second band was then presented asynchronously with the target band: recovery from interference was interpreted as reflection perceptual segregation. While the listeners with hearing loss tended to perform more poorly overall, the pattern of their results was similar to that of the listeners with normal hearing. [Work supported by the NIDCD R01-DC01507.]