ASA 125th Meeting Ottawa 1993 May

3aMU4. Across-channel processing of amplitude modulation in cochlear hearing-impaired listeners.

J. W. Hall, III

J. H. Grose

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

Over the past few years, there have been several studies that have examined across-channel effects related to amplitude modulation (AM). Some of these effects, notably comodulation masking release (CMR), modulation detection interference (MDI), and monaural envelope correlation perception, have been hypothesized to be related to the analysis of signals in complex noise backgrounds, and to auditory grouping. Several studies of cochlear-impaired listeners using these paradigms have recently been completed. Cochlear-impaired listeners often report having difficulty processing signals in noisy backgrounds, and it is possible that the study of across-channel processes involving the coding of AM can shed light upon some components of this disability. Because physiological studies have indicated that neural/central abnormalities can occur secondary to cochlear lesions, it is worthwhile to consider the effect of cochlear hearing loss on across-channel auditory processes. At this point, the extent to which cochlear-based losses in humans are associated with some degree of concomitant neural deficit is largely unknown. One of the specific goals of the research was to determine the peripheral versus central contributions to the hearing loss related deficits in the processing of across-channel AM cues. The results of the studies indicated that relatively mild acquired cochlear losses in adults are associated with effects that can be accounted for in terms of peripheral processing deficits. [Research supported by NIH NIDCD.]