Effect of aspirin on transiently evoked otoacoustic emissions in guinea pigs.

Aspirin and other salicylates influence otoacoustic emissions (OAEs), but changes in transiently evoked OAEs (TEOAEs) following aspirin intake have not been studied experimentally. We examined the changes in TEOAEs, together with auditory brainstem responses (ABRs), in guinea pigs before and after the intravenous injection of aspirin (100 and 400 mg/kg). TEOAE power decreased slowly after the injection in a dose-dependent manner. Mean minimal values were detected 20 min after the injection of 100 mg/kg, and 40 min after the injection of 400 mg/kg. TEOAE power recovered slowly. These changes were paralleled by shifts in ABR thresholds. The magnitude of the decrease in the frequency components in the TEOAE frequency power spectrum was similar. In one guinea pig, TEOAE power returned to the pretreatment level 7 h after the injection. Findings support the results of in vitro studies that salicylates affect electromotility in isolated outer hair cells from guinea pig cochlea.