Auditory Nerve: Electrical Stimulation in Man

Auditory perceptions produced in a person deaf to acoustic stimulation were studied by electrically exciting the auditory nerve through permanently implanted electrodes. Pulsed current as small as 1 microampere peak-to-peak could be perceived. Pitch, as reported by the subject, varied with electrode selection, current amplitude, and pulse repetition rate from about 70 to at least 300 pulses per second. Loudness increased with amplitude and duration of pulse stimuli, and to a lesser extent with repetition rate. The total range in amplitude of the stimulus, from threshold to an uncomfortable loudness, was 15 to 20 decibels. Simultaneous stimulation in separate electrodes produced a number of complex effects.