Electrode placement and mode of recording (differential vs. single-ended) effects on the early auditory-evoked response.
The effects of electrode placement and mode of recording (single-ended vs. differential) on latencies and amplitudes of the early auditory-evoked response were studied. The following electrode arrays were evaluated (1) vertex-neck, (2) forehead-ear canal (Enhancer I), and (3) vertex-nape. Responses were obtained on 10 normally hearing subjects at sensation levels (SLs) ranging from 15 to 75 dB. Test-retest reliability was excellent for absolute and interwave latencies for all conditions. The reliability of absolute amplitude was poor, and the stability of the amplitude ratios between waves I and V was even worse. No consistent absolute or interwave latency differences were found among electrode montages. The amplitude data suggest that the forehead-ear canal montage is preferred for differential diagnosis because it enhances the probability of detecting wave I. The electrophysiologic threshold for wave I was 5-10 dB lower with the Enhancer I. However, the vertex-neck and vertex-nape combinations are best for estimating auditory sensitivity because they gave the largest wave V amplitudes and 10-dB lower electrophysiologic thresholds. Although the differential vertex-neck and single-ended vertex-nape recordings yielded comparable results, the single-ended montage employs only two electrodes and the test leads do not require rearrangement when the test ear changes.
Beattie
R C
RC
Department of Communicative Disorders, California State University, Long Beach.
Taggart
L A
LA
D000328:Adult; D000669:Amplifiers, Electronic; D001300:Audiometry, Evoked Response / Q000295:instrumentation / Q000379:methods*; D004566:Electrodes; D005260:Female; D006801:Humans; D008297:Male