Gender distinctions and lateral asymmetry in the low-level auditory brainstem response of the human neonate

Threshold measures of auditory brainstem response (ABR) were generated in 7 2 full-term newborn infants in response to clicks and tone burst stimuli be tween 500 and 8000 Hz as detailed in a previous study. These results were f urther analyzed for differences in response related to ear (lateral asymmet ry) and subject gender. Thresholds obtained in male infants were significan tly lower than those of females (P = 0.0485). The greatest differences in t hreshold between male and female infants occurs in the right ear (7.45 dB) as opposed to the left ear (1.56 dB). Both male and female infants have sig nificantly larger wave V amplitude elicited from the right eat than the lef t (P = 0.0002) using low-level stimuli. Also, as has been no;ed in adults, female infants have larger amplitude ABRs than males (P = 0.0018), but ampl itude differences across gender are significant only in the right ear (ear by gender interaction P = 0.0278). Results of this study indicate that gend er differences and lateral asymmetry in auditory function are not a result of gender bias for or unbalanced auditory trauma, but a biologically signif icant phenomenon that is present at birth. The argument is made that superi or right ear performance may be part of cerebral laterality in auditory fun ction. (C) 1998 Elsevier Science B.V. All rights reserved.