ASA 125th Meeting Ottawa 1993 May

3pMU3. Auditory image formation using a CMR paradigm: The role of AM, FM, and harmonicity.

J. H. Grose

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

When a pair of comodulated narrow bands of noise is inserted into a larger set of independently comodulated noisebands, the amount of comodulation masking release (CMR) measured for the larger set is reduced. This interference effect can be mitigated to some extent by presenting further bands of noise to the contralateral ear which are comodulated with the intervening pair of bands. One interpretation of this release from interference is that the additional contralateral bands serve to draw the intervening pair of bands into a separate auditory image and that this more distinct segregation of the two sets of comodulated bands allows the auditory system to better perform a CMR on the original comodulated set. The purpose of this study was to apply the paradigm to situations where the commonality between the intervening pair of noisebands and the contralateral bands was some combination of three variables: AM (correlated, uncorrelated), FM (present, absent), and spectral spacing (harmonic, inharmonic). Results indicated that the release from interference occurred most often when coherent AM featured in the commonality, although a slight effect of coherent FM was also observed. [Work supported by the NIDCD R01-DC01507.]