Estimating mechanical responses to pulsatile electrical stimulation of the cochlea

This study estimated the mechanical response of the cochlea to pulsatile electrical stimulation of the scala tympani of the cat. The auditory nerve compound action potential evoked by an acoustic probe was forward-masked by a train of charge-balanced biphasic current pulses. Masking as a function of probe frequency reflected the excitation pattern of the response to the masker and resembled the spectrum of the electrical stimulus. Both pulse rate and pulse width influenced the degree of masking. The vibration of a region of the basilar membrane was estimated by recording the local cochlear microphonic evoked by biphasic pulses. The amplitude of the cochlear microphonic was proportional to the amplitude of the spectral component of the electrical stimulus to which the local cochlear microphonic was tuned. These results are consistent with the generation of a mechanical response to the electrical stimulus.