Individual specificity of the late components of averaged electroencephalic responses (AERS) evoked by repeated clicks.

Abstract

Averaged electroencephalic responses (AERs) were evoked from each of 8 normal hearing subjects on 8 different days by 150 clicks presented at 60 dB sensation level during Design I. For Design II, AERs were evoked from the subjects by 150 clicks presented at 60, 20, and 5 dB SL presented in three orders on each of two different days. Each subject was classified as either a good, average, or poor responder based upon the relative magnitude of the mean of his eight N 1 -P 2 amplitudes evoked during Design I. Findings suggest: (1) intrasubject variability of the late-peak amplitudes and latencies of the averaged electroencephalic wave form is as extensive as intersubject variability of these components; (2) responder classifications of subjects remain consistent from one design to another; (3) the intrasubject mean amplitude of the N 1 -P 2 peak and the intrasubject mean latency and standard deviation of the N 1 peak exhibit tendencies toward individual specificity; (4) the N 1 -P 2 peak amplitude reduces significantly from the first 100 seconds to the third 100 seconds of an averaging session; (5) it is more efficient to average over 150 clicks than it is to average over 50 clicks at low sensation levels; and (6) poor responders perform as well, or better, than good or average responders at low sensation levels.