Speech perception and brain laterality: the effect of ear advantage on auditory event-related potentials

Dichotic listening has been used for assessing asymmetries in processing auditory stimuli. It is known that there is better recognition of dichotic stimuli in the right ear with verbal stimuli (right ear advantage, REA) by the majority of the subjects. We were interested in the psychophysiological correlates of ear advantage as it is manifested in event-related potentials (ERP). We compared ERPs to monaural and dichotic syllables in stable REA and LEA subjects. The most consistent finding was that REA subjects show larger positive ERP deflections over the left hemisphere (maximal at T5) and LEA subjects over the right hemisphere (maximal at T6) both at the latency range of 320-340 msec. Thus, brain event-related potentials support the contention that the REA and LEA reflect differential activation of the left and right hemispheres, respectively.