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

5pPP9. Cochlear acoustic reflectance and traveling wave delay.

Barry P. Kimberley

Dept. of Surgery, Univ. of Calgary, 3330 Hospital Dr. N. W., Calgary, Alberta T2N 4N1, Canada

Greg Shaw

Univ. of Calgary

Christopher Shera

Eaton Peabody Labs.

Jont B. Allen

Bell Labs.

Inner ear acoustic impedance and reflectance, SFOAEs, DPEs, and PTTs were measured with a calibrated probe situated in the ear canal of normal-hearing subjects. The use of a calibrated probe allowed for the conversion of the SFOAE recordings into reflectance. In a number of subjects, low stimulus levels results in rippling of the reflectance. The phase slope of the acoustic reflectance was found to be a linear over a narrow range of frequencies. This slope is taken as equivalent to the traveling wave delay to the corresponding frequency(ies). Traveling wave delay estimates (reflectance phase slope) however did not change as stimulus level ranged from 50 to 10 dB SPL. This is in contrast to previous traveling wave delay estimates using DPEs where delay increased with a decrease in stimulus level [Kimberley et al., 1343--1350 (1993)]. The discrepancy between DPE-based and SFOAE-based estimates of traveling wave delay is discussed.