Head size as a basis of gender difference in the latency of the brainstem auditory-evoked response.

In order to discuss the source of gender difference in the latencies of the brainstem auditory-evoked response (ABR), correlation analysis between head size (nasion to inion, ear to ear and circumference) and ABR latencies were investigated in 107 adults (57 males and 50 females) with normal hearing. Wave III and wave V latencies and I-III and I-V interpeak latency intervals (IPL) were significantly shorter in females than in males. Moreover, head size of the male subjects was significantly larger than the female subjects' head size with respect to all three parameters. Significant positive correlations were obtained between head size and the above-mentioned ABR wave latencies and IPLs, even when each gender was analyzed separately. These results suggest that head size, which may reflect brain size, is one of the important factors for the basis of gender difference in ABR latencies.