Electrophysiological Gap Detection Test Using Auditory Evoked Brainstem Responses

Abstract

Temporal resolution is an important factor in auditory processing, especially in speech recognition. For evaluation in humans, many experiments such as gap detection test (gap test), have been conducted mostly with psychoacoustic methods. To objectify temporal resolution, we designed an electrophysiological gap test using auditory evoked brainstem responses (ABRs). ABRs were elicited by a probe tone (4 kHz, 75 dBnHL, 2 msec duration, tone burst) with a preceding masker tone (4 kHz, 75 dBnHL, 50 msec duration, tone burst) in 20 young subjects with normal hearing. As two tone intervals (gaps) were shortened from 10 msec by 2 msec, the amplitudes of wave V were decreased and became undetectable. The thresholds for wave V detection regarded as gap detection thresholds ranged from 2 to 6 msec with an average of 4.8 msec, which is similar to the results of the psychoacoustic gap test introduced by Shailer and Moore in 1989.
This test is useful in the objective evaluation of temporal resolution in humans.