Middle Components of Human Auditory Averaged Electroencephalic Response: Waveform Variations During Averaging

Abstract

The bases for variations of the middle-component (8–50 ms) auditory averaged electroencephalic response (AER) to clicks during the averaging process were explored by examining (1) the trend of the mean variance of the averaged waveform, (2) averaged waveforms generated by successive blocks of stimuli fractioned from a total of 512 stimuli, and (3) averaged waveforms generated by successive, but partially overlapping, blocks of responses recorded for a train of 512 stimuli. These analyses indicated no systematic changes in peak latencies or peak-to-peak amplitudes as stimulation progressed. Fluctuations in middle AER waveform are more readily explained by non-stationarity of the background electrophysiologic noise. Previously reported amplitude reduction with increasing stimulus number possibly can be explained by progressive reduction of the background noise on which the consistent-amplitude middle components are superimposed.

Key Words:

• Electric response audiometry
• Electroencephalic audiometry
• Middle components of auditory averaged electroencephalic response
• Auditory averaged electroencephalic response variability
• Adaptation/habiituaton