ASA 125th Meeting Ottawa 1993 May

3aPP3. Correlation of distortion product otoacoustic emissions (DPOAE) with hearing loss produced in a ``toughening'' exposure.

Donald Henderson

Malini Subramaniam

Hear. Res. Labs., State Univ. of New York at Buffalo, 215 Parker Hall, Buffalo, NY 14214

The relation between distortion product otoacoustic emissions (DPOAE) and hearing loss was studied using a ``toughening'' exposure. The subjects were monaural chinchillas [N=5]; DPOAE were measured using a Virtual 330 and hearing was estimated using evoked potentials recorded from a chronic electrode in the colliculus. Hearing thresholds and DPOAE were measured before any exposure began, then after each 6-h exposure of 0.5 kHz OB at 95 dB SPL for 10 days and, finally, 5 days after the last exposure. Over the 10 days of exposure, the daily threshold shifts became progressively less. Initially, the DPOAE were depressed below the noise of the DPOAE system, but by days 8 to 10, the subjects had recovered to pre-exposure levels even though there were still significant shifts in hearing thresholds. Five days post-exposure, hearing levels were normal and DPOAE were normal or enhanced. Results will be discussed in terms of ``toughening'' induced by noise exposure. [Work supported by NIH 1 R01 DC01237-01A11.]