Auditory brainstem responses to level-specific chirps in normal-hearing adults.

Abstract

Upward chirps are often designed to compensate for the cochlear traveling wave delay which is regarded as independent of stimulation level. A chirp based on a traveling wave model is therefore referred to as a level-independent chirp. Another compensation strategy, for instance based on frequency-specific auditory brainstem response (ABR) latencies, results in a chirp that changes with stimulation level and is therefore referred to as a level-dependent chirp. One such strategy, the direct approach, results in a chirp family that is called the level-specific chirp. The level dependence is in agreement with the findings that the chirp, which generates the largest ABR in normal-hearing adults, has a duration (sweeping rate) that changes with stimulus level. A direct comparison of ABRs to a fixed chirp and to a level-specific chirp has not been performed at higher levels of stimulation where the differences are thought to have the greatest effect on the ABR characteristics from normal-hearing adults.