The effect of broadband noise on the human brain-stem auditory evoked response. III. Anatomic locus.
The effects of broadband noise on the brain-stem auditory evoked response (BAER) are reported for two experiments. Experiment 1 used a high-pass subtractive-masking technique and covaried derived bandwidth and continuous broadband noise level. Comparison of responses to half-octave wide derived bands in the presence of within-band noise showed that wave V latency changes were greater than could be explained on the basis of shifts in the cochlear region responsible for generating the response. The magnitude of within-band noise-induced wave V latency shift was independent of the frequency separation of the masker cutoffs. In experiment 2 the effects of noise level and rate on waves I, III, and V of the BAER were evaluated. Peak latencies increased and peak amplitudes decreased with increasing noise level and rate. Higher noise levels and rates produced an increased central (I-V) conduction time in which the wave III-V increase was greater than the wave I-III increase. Together, these results are most consistent with the hypothesis that a nonplace, central auditory mechanism produces most of the noise-induced latency shifts in normal-hearing adults.
D000328:Adult; D001305:Auditory Fatigue / Q000502:physiology*; D001306:Auditory Pathways / Q000502:physiology; D001931:Brain Mapping; D001933:Brain Stem / Q000502:physiology*; D003056:Cochlear Nerve / Q000502:physiology*; D005072:Evoked Potentials, Auditory; D006801:Humans; D009622:Noise / Q000009:adverse effects*; D010470:Perceptual Masking / Q000502:physiology; D010897:Pitch Discrimination / Q000502:physiology; D011571:Psychoacoustics; D011930:Reaction Time / Q000502:physiology