Sex and hemispheric differences for rapid auditory processing in normal adults.

Previous research suggests that left hemisphere specialisation for processing speech may specifically depend on rate-specific parameters, with rapidly successive or faster changing acoustic stimuli (e.g. stop consonant-vowel syllables) processed preferentially by the left hemisphere. The current study further investigates the involvement of the left hemisphere in processing rapidly changing auditory information, and examines the effects of sex on the organisation of this function. Twenty subjects participated in an auditory discrimination task involving the target identification of a two-tone sequence presented to one ear, paired with white noise to the contralateral ear. Analyses demonstrated a right ear advantage for males only at the shorter interstimulus interval durations (mean = 20 msec) whereas no ear advantage was observed for women. These results suggest that the male brain is more lateralised for the processing of rapidly presented auditory tones, specifically at shorter stimulus durations.