The influence of choline salicylate ototoxicity on tone-evoked cochlear microphonics and click-evoked N1 potentials as recorded from the round window of anesthetized guinea pigs was studied. An increased threshold for the 1-μv sensitivity curve was found, and more dramatically, a marked reduction in dynamic range of cochlear microphonics was observed. Whereas, no effect was found on the latency of nerve evoked potential response, amplitude was reduced following choline salicylate ingestion. These effects were dose dependent and followed a specific time course.
The findings of this study are interpreted to indicate that the functional target site of salicylates in the cochlea is the hair cell. Moreover, the results suggest that clinical tests of suprathreshold hearing function may be a more sensitive indicator of salicylate toxicity than threshold evaluation.