Partial dissociation of spontaneous otoacoustic emissions and distortion products during aspirin use in humans.

Otoacoustic emissions (OAEs) of two types--spontaneous and evoked distortion products--were studied before, during, and following a period of aspirin use. As previously reported, aspirin consumption uniformly reduced the spontaneous OAEs (SOAEs) to unmeasurable or extremely low levels. Aspirin consumption also reduced the amplitude of the evoked distortion products (EDPs) but did not eliminate them entirely. The amplitude of the EDP and its change with aspirin consumption were related to both the proximity of the EDP to the frequency of the SOAE and to the level of the primaries producing the EDP. At low primary levels, even with the SOAE absent (due to aspirin consumption, or suppression), EDPs near the SOAE frequency were 10-20 dB higher than when they were 100 Hz away from the SOAE frequency.