Abstract
The relationship between alternating current (AC)-induced otoacoustic emissions (OAEs) and the cochlear outer hair cells (OHCs) was examined. Injection of an AC into the scala media of the guinea pig cochlea, together with simultaneous stimulation by a pure tone, induced sound emissions in the ear canal at the frequencies of the AC and intermodulation distortion products. Amplitude of these emissions changed depending on the frequency of the injected AC or stimulating tone. The amplitude and its fre quencydependence were decreased by selective damage to OHCs by ototoxic agents, and the decrease depended on the extent of the OHC damage, especially at the AC injection site. It is suggested that OHC acts as an electromechanical transducer in the cochlea and is responsible for the generation of the AC-induced OAEs. A nonlinearity to produce the intermodulation distortion was more susceptible to the OHC damage than the electromechanical transducing process.
