Fowler C G
VA Medical Center, Long Beach, California.
J Speech Hear Res. 1992 Feb;35(1):167-74. doi: 10.1044/jshr.3501.167.
The purpose of this investigation was to determine the effects of stimulus phase on the latencies and morphology of the auditory brainstem response (ABR) of normal-hearing subjects. Although click stimuli produced equivalent ABR latencies for the rarefaction and condensation phases, the subtraction of the waveforms from the two phases yielded a difference potential. Tone pip stimuli produced polarity differences that were inversely related to stimulus frequency: the higher the frequency, the smaller the ABR latency differences between responses to rarefaction and condensation stimuli, and the smaller the difference potentials. Thus, whereas the latency of click-evoked ABR is dominated by high-frequency responses with equivalent latencies regardless of stimulus phase, low-frequency responses contribute to the overall morphology of the ABR that yields the phasic difference potential. The implications of these findings are discussed with reference to subjects with high-frequency hearing losses.
