Sex and Hemispheric Differences for Rapid Auditory Processing in Normal Adults

Abstract

Previous research suggests that left hemisphere specialisation for processing speech m ay specifically depend on rate-specific parameters, with rapidly successive or faster changing acoustic stimuli (e.g. stop consonant±vow el syllables) processed preferentially by the left hemisphere. The current study further investigates the involvem ent 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 m ales only at the shorter interstimulus interval durations (mean = 20msec) 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.

Phonetic Perception and the Temporal Cortex

“…A more recent study adds further support to this hypothesis by demonstrating a significant REA in normal adult males for detecting rapidly changing nonverbal tone sequences. No significant ear advantage was found when the same sequences were presented more slowly (Brown et al, 1999).…”

Neurobiology of Speech Perception

“…These results indicate that specialization of the left hemisphere for rapid acoustic change may underlie specialization for speech perception. This hypothesis is further supported by evidence that intact human listeners exhibit an REA not only for speech, but also for tone sequences that change within the time frame critical to speech (Brown et al 1995). These findings are consistent with the hierarchical dependence of speech perception upon the basic ability to process rapid acoustic change, and lead to a provocative hypothesis that the left hemisphere regions that subserve speech may be fundamentally specialized for the processing of rapidly changing acoustic information-an assertion consistent with the observation of left hemisphere specialization for complex auditory discrimination in nonhuman species (e.g.…”

Of bats and men

“…A similar pattern of results was also found in subsequent studies using the same stimuli within a dichotic listening paradigm with healthy adults. A significantly greater right ear (LH) advantage was found for speech syllables with 40-ms compared with 80-ms formant transitions (Schwartz and Tallal 1980) as well as tone sequences presented with brief (mean ϭ 20 ms) but not longer ISI durations, and only for males (Brown et al 1999).…”