Abstract
The binaural interaction (BI) in the auditory brainstem response (ABR) was studied in ten young adults with normal hearing to rarefaction click stimuli. A special care was taken on stimulus presentation; a novel stimulus paradigm was devised to reduce the influence of the acoustic reflex on the ABR and to record each response with almost the same signal-to-noise ratio. For that purpose, sequences of stimuli were periodically presented in the order of right monaural-left monaural-binaural-left monaural-right-monaural-binaural, with an inter stimulus interval of 22ms. BI was obtained by subtracting the sum of the monaurally (ipsilaterally and contralaterally) evoked potentials from the binaurally evoked potentials. The waveform of BI was composed of three positive peaks and two negative troughs, and the major BI appeared in the region of the brainstem response wave V and VI. There was no evidence of the interaction in the early portion of ABR. BI showed a linear dependence on intensity; latency increased and amplitude decreased lineally as the stimulus intensity reduced.
