ASA 130th Meeting - St. Louis, MO - 1995 Nov 27 .. Dec 01

4aPP8. Correlations between auditory-filter shape parameters measured at proximal center frequencies.

Marc A. Fagelson

Program in Comm. Sci. & Disord., Univ. of Texas, Austin, TX 78712

Craig A. Champlin

Univ. of Texas, Austin, TX 78712

Auditory-filter shape parameters in 20 normal-hearing listeners were determined at center frequencies (CFs) of 913, 1095, 3651, and 4382 Hz using the five-point roex (p,r) method. Slopes of the filters' skirts were correlated for the CFs in each frequency region at both low and high stimulus levels. In the (lambda)=1000-Hz region, the auditory filters' low-frequency slopes were significantly correlated at the low and high stimulus levels, while the high-frequency slopes were associated at the high, but not the low level. In the (lambda)=4000-Hz region the relationships were clearer as the low-frequency and high-frequency filter skirts diverged at the low level, but were significantly correlated at high stimulus levels. Level dependencies in auditory-filter shapes indicated subtle differences in cochlear frequency analysis at proximal places along the basilar membrane diminished as signal level was increased. Conversely, in those situations most likely to be affected by active processing along the partition, such as the low-level and high-frequency conditions, auditory filters centered at neighboring frequencies often did not resemble one another. This suggests that active cochlear mechanisms are not uniformly distributed throughout the length of the basilar membrane. [Work supported by the College of Communication (Jamail Grant) and NIDCD.]