ESTIMATING MECHANICAL RESPONSES TO PULSATILE ELECTRICAL-STIMULATION OF THE COCHLEA

This study estimated the mechanical response of the cochlea to pulsati le electrical stimulation of the scala tympani of the cat. The auditor y nerve compound action potential evoked by an acoustic probe was forw ard-masked by a train of charge-balanced biphasic current pulses. Mask ing as a function of probe frequency reflected the excitation pattern of the response to the masker and resembled the spectrum of the electr ical stimulus. Both pulse rate and pulse width influenced the degree o f masking. The vibration of a region of the basilar membrane was estim ated by recording the local cochlear microphonic evoked by biphasic pu lses. The amplitude of the cochlear microphonic was proportional to th e amplitude of the spectral component of the electrical stimulus to wh ich the local cochlear microphonic was tuned. These results are consis tent with the generation of a mechanical response to the electrical st imulus.