Relationships between otoacoustic emissions and a proxy measure of cochlear length derived from the auditory brainstem response.

Brief tones of 1.0 and 8.0 kHz were used to evoke auditory brainstem responses (ABRs), and the differences between the wave-V latencies for those two frequencies were used as a proxy for cochlear length. The tone bursts (8 ms in duration including 2-ms rise/fall times, and 82 dB in level) were, or were not, accompanied by a continuous, moderately intense noise band, highpass filtered immediately above the tone. The proxy values for length were compared with various measures of otoacoustic emissions (OAEs) obtained from the same ears. All the correlations were low, suggesting that cochlear length, as measured by this proxy at least, is not strongly related to the various group and individual differences that exist in OAEs. Female latencies did not differ across the menstrual cycle, and the proxy length measure exhibited no sex difference (either for menses females vs. males or midluteal females vs. males) when the highpass noises were used. However, when the subjects were partitioned into Whites and Non-Whites, a substantial sex difference in cochlear length did emerge for the White group, although the correlations with OAEs remained low. Head size was not highly correlated with any of the ABR measures.