A negative potential at the latency 3 msec in ABR recording

The Auditory brainstem responses (ABRs) of 606 ears were evaluated from 425 profoundly deaf patients. A potential with negative deflection was found at the latency of 3 msec in 48 ears of 37 patients above the intensity of 80 dBnHL. As intensity was increased, the amplitude was larger and latency decreased. The response reappeared in retesting, and did not disappear with masking contralateral ear to click stimulation. We speculated the response to be the physiological potential evoked by acoustic stimulation, neither electrical artifact nor shadow response from the good ear, and we concluded the response is one type of ABR waveform recorded only in peripherally profound deafness, since a few of low frequency threshold remained and none of central disorder was found.