Rapid force production in the cochlea.

Electrical stimulation of the mammalian cochlea causes a mechanical response which produces acoustic signals at the frequency of the electrical current. These electrically-evoked acoustic emissions can be as large as 34 dB SPL. Concurrent acoustic stimuli can enhance the emission response. Comparison of the enhancement effect with the cochlear microphonic (CM) suggests that the emissions originate from the outer hair cells (OHC). Frequency response measurements indicate a rate-limiting time constant for the force-generating process which is less than 35 microseconds.