Monaural determinants of individual differences in the human ABR binaural interaction component. Psychophysiology, 57, S1.

The auditory brainstem response binaural interaction component (ABR‐BIC) is a difference waveform. Subtraction isolates this component of the binaural response from the artificial sum of monaural responses to left and right stimulation. The DN1 peak negativity of the ABR‐BIC (binaural < summed monaural) occurs during or after the ABR’s positive wave V peak. Unknown was if the apparent attentional modulation of human DN1 (Ikeda, 2015, Hearing Research, 325, 27–34), rather, had bilateral monaural origins. Participants heard either tone‐pips or clicks via monaural left, right, or binaural presentation (Ikeda, 2015). These participants selectively attended to sounds or to concurrently presented visual stimuli. DN1s for tone‐pips were unequivocally present, i.e., differing significantly from zero, only with auditory selective attention. DN1s with clicks proved significantly present, regardless of attended modality. Beyond DN1’s presence, auditory selective attention significantly increased only monaural and binaural tone‐pip Wave‐V peak amplitudes, yet not tone‐pip DN1s. Attentional influences on tone‐pip DN1 presence thus have bilateral monaural origins. Further, DN1 amplitudes correlated more strongly with the monaural than the binaural wave V, particularly with right monaural presentation. A multiple parallel mediator model characterized a monaural determinant of individual differences in DN1. This pre‐attentive determinant of DN1 relied on how, with right‐ear presentation, Wave V increased for clicks over tone‐pips.