Rise time of pure-tone stimuli in brain stem response audiometry

In order to identify the area of a pure tone stimulus effective for evoking the auditory brain stem response (ABR), the amplitude, latency and detectability of the response were measured as a function of stimulus rise time with a fixed onset slope of a linear-shaped envelope. The test was performed on 8 normal adults with 2- and 0.5 -kHz tone pips at various intensity levels from 50 to 15 dB HL. The ABR was elicited by the very early part of the stimulus, and the succeeding part had little effect in eliciting the response, if the initial part was intense enough to evoke the response. At lower intensity levels, where the initial part did not reach an intensity level sufficient to evoke a full size response, a limited period of the succeeding part participated in evoking the response. The effective duration of the stimulus was estimated at 1.5 ms for 2 kHz and at 3 ms for 0.5 kHz. From these results, the authors propose that acceptable rise times of pure-tone stimuli for brain stem response audiometry are 3, 2, 1.5 and 1 ms for tone pips of 0.5, 1, 2 and 4 kHz, respectively.