Gender, head size, and ABRs examined in large clinical sample.

Intergender differences in auditory brain stem response (ABR) latencies have been attributed to intergender differences in head size. We examined ABR data obtained clinically and head dimensions measured from mastoid to mastoid and mastoid to vertex to derive horizontal and vertical vectors which might scale lengths of horizontally and vertically oriented pathways, respectively. Correlations with ABR latencies were all somewhat weak, and slopes of regressions were found to be too small to fully account for intergender latency differences. Head-size matched male and female samples also demonstrated significant differences in wave V latency, and, even in cases with relatively large heads, the use of a head-size correction could not be justified. The coupling between head dimensions and the I-V interpeak interval appears to be small enough to be ignored for clinical purposes. Nevertheless, to the extent to which relationships exist between head dimensions and ABR latency measures, this nonpathologic variable may be completely neutralized through the use of interpeak latency ratios (e.g., wave V latency divided by wave I latency).