DEVELOPMENT of cortical audiometry,1,2 an accurate, objective method of evaluating auditory acuity in man, was made possible through the introduction of computer techniques which enabled the averaging of many individual electroencephalographic recordings following acoustic stimulation. Geisler and associates3 were the first to show that it was possible to record at the inion responses to clicks in the awake man by means of a computer averaging technique. They reported that the inion response was cortical in origin. It was found by Bickford and associates,4,5 however, that the short-latency inion response originated from the extracranial musculature, was mediated by the vestibular apparatus, and could be evoked only by a click of an intensity well above the subjective auditory threshold.
In 1964 Cody and associates5 differentiated between the short-latency myogenic inion response and a longer-latency cochlearly mediated brain response that could be recorded maximally from the scalp over the