title: Frequency specificity of the human auditory brainstem and middle latency responses using notched noise masking.
abstract: This study investigated the frequency specificity of the auditory brainstem and middle latency responses to 80 and 90 dB ppe SPL 500-Hz and 90 dB ppe SPL 2000-Hz tonebursts. The stimuli were brief (2-1-2 cycle) linear-gated tonebursts. ABR/MLRs were recorded using two electrode montages: (1) Cz-nape of neck and (2) Cz-ipsilateral earlobe. Cochlear contributions to ABR wave V-Na and MLR waves Na-Pa and Pa-Nb were assessed by plotting notched noise tuning curves which showed amplitudes and latencies as a function of center frequency of the noise masker [Abdala and Folsom, J. Acoust. Soc. Am. 97, 2394 (1995); ibid. 98, 921 (1995)]. Maxima in the response amplitude profiles for the ABR and MLR to 80 dB ppe SPL tonebursts occurred within one-half octave of the nominal stimulus frequency, with minimal contributions to the responses from frequencies greater than one octave away. At 90 dB ppe SPL, contributions came from a slightly broader frequency region for both stimulus frequencies. Thus, the ABR/MLR to 80 dB ppe SPL tonebursts shows good frequency specificity which decreases at 90 dB ppe SPL. No significant differences exist in frequency specificity of: (1) ABR wave V-Na versus MLR waves Na-Pa and Pa-Nb at either stimulus frequency or intensity; and (2) ABR/MLRs recorded using the two electrode montages.
authors.affiliation: Discipline of Audiology, The University of Auckland, New Zealand.
authors.forename: P A
authors.initials: PA
authors.lastname: Oates
authors.forename: S C
authors.initials: SC
authors.lastname: Purdy
mesh_terms: D001309:Auditory Threshold / Q000502:physiology; D001933:Brain Stem / Q000502:physiology*; D016057:Evoked Potentials, Auditory, Brain Stem / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008307:Malleus / Q000502:physiology; D010470:Perceptual Masking / Q000502:physiology*; D010898:Pitch Perception / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology*; D012016:Reference Values; D014432:Tympanic Membrane / Q000502:physiology