An electroencephalographic evoked response correlate of auditory adaptation

Normal‐hearing subjects were evaluated to determine whether changes in behavioral auditory thresholds, in both a heterophonic and homophonic listening condition, would produce equal two dissimilar changes in the amplitude and latency of the auditory evoked potential. Each subject completed a preadaptation loudness balance prior to any stimulation. A 2000‐Hz pure tone was then presented to the subject's right ear for a period of 7 min at a level of 60 dB SPL. During this 7‐min adapting period four AER runs consisting of 32 tone pips superimposed on the adapting tone were presented. Finally, a perstimulatory loudness balance was completed while the adapting tone had been on for 7 min. Measurements of amplitude and latency of the evoked potentials were analyzed and results suggest that more adaptation occurred for the homophonic condition. However, a significant amount of decrement in the amplitude of the monaurally elicited AER was measured for both the homophonic and heterophonic condition. It was suggested that AER may be a sensitive measurement technique of auditory adaptation.