Effect of sleep on binaural interaction in auditory brainstem response and middle latency response.

Binaural interaction (BI) in auditory brainstem response (ABR) and middle latency response (MLR) was measured in 14 adults with normal hearing in the awake and asleep states. The ABR and MLR were recorded with click stimuli given monaurally and binaurally. Four peak-to-peak amplitudes of the response waveforms were measured, and the BI was determined from the amplitude difference between the summed monaural and binaural responses expressed in percent of the summed monaural responses. The magnitude of BI was smallest in ABR (waves I'-V) and largest in the later component of MLR (Pa-Nb) in both the waking and sleeping states. BI values for the peak-to-peak amplitudes in the ABR and MLR were significantly lower (p less than 0.025) in the sleeping state than in the waking state.