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Sensitivity to interaural time differences at high frequencies is demonstrated in a number of experiments. Two types of waveforms are used—bands of noise and two-tone complexes. Variables studied are rate and depth of fluctuation of the envelope, overall intensity, and additivity of interaural time information across frequency regions. In many conditions of listening, sensitivity to interaural time differences at high frequencies compares favorably with sensitivity at low frequencies—good performace requires only tens of microseconds of interaural time delay. Subject Classification: [43]65.62, [43]65.68.

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Click-evoked otoacoustic emissions (CEOAEs) are echo-like waveforms emitted by normal-hearing cochleas in response to a brief transient. CEOAEs are known to be stronger in females than in males. In this experiment, the CEOAEs of homosexual and bisexual females were found to be intermediate to those of heterosexual females and heterosexual males. A parsimonious explanation is that the auditory systems of homosexual and bisexual females, and the brain structures responsible for their sexual orientation, have been partially masculinized by exposure to high levels of androgens prenatally. No difference in CEOAEs was observed between homosexual and heterosexual males.Evidence continues to accumulate about the biological concomitants of human homosexuality. To date, homosexual males have been reported to have larger suprachiasmatic nuclei of the hypothalamus (1), smaller interstitial nuclei of the anterior hypothalamus (2), larger anterior commissures (3), and thicker isthmuses of the corpus callosum (4) than heterosexual males. (Which, if any, of these concomitants is actually a substrate for homosexual behavior-as distinguished from a structure that simply covaries with homosexual behavior and its structural substrates-is yet to be determined.) Supplementing the findings about differences in brain structure are findings about the heritability of homosexuality. Studies of twins suggest heritability values of about 0.4-0.7 for homosexuality in both males and females (5, 6), and there is evidence for a linkage between certain markers on the X chromosome and sexual orientation in males but not in females (7,8).With the exception of the heritability study on twins (6), all of the current evidence for biological concomitants of homosexuality is for males only. Here, we report that the peripheral auditory systems of homosexual females differ from those of heterosexual females, and the nature of the difference is consistent with the idea that homosexual females are exposed to higher levels of androgens prenatally than are heterosexual females.Otoacoustic emissions (OAEs) are weak sounds produced by elements in the inner ear (refs. 9 and 10; for a review, see ref. 11). These sounds can be measured using a miniature microphone attached to a probe tip inserted into the external ear canal. There are several types of OAE, but only two will be considered in this paper. Click-evoked otoacoustic emissions (CEOAEs) are echo-like waveforms that are emitted in response to a brief transient sound. A click of about one-tenth of a millisecond in duration can produce a CEOAE lasting tens of milliseconds in any person having a normal cochlea and middle-ear system. Because CEOAE waveforms are weak, the responses to many clicks must be averaged for a CEOAE waveform to be obtained. CEOAE waveforms differ considerably across ears, but seem to be stable within an ear (12, 13).Spontaneous otoacoustic emissions (SOAEs) are tonal or narrow-band sounds that are continuously emitted by an ear in the absence of eliciting acoustic stimulation....

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Five studies have examined the relationship between sexual orientation and the relative lengths of the 2nd and 4th fingers (the 2D:4D ratio). Although differences have commonly been found between heterosexuals and homosexuals, the direction of the difference has not been consistent across studies. The original data from all five studies were reanalyzed in a search for possible explanations of the discrepancies. Because ethnicity is known to affect the 2D:4D ratio, the reanalysis focused on participants who identified themselves as White or Caucasian, the ethnic group that was most numerous in all of the studies. Age differences did not account for the discrepancies. Differences in variability within different groups were minor. One interesting result to emerge from the reanalysis was that the 2D:4D ratios for the homosexual groups were relatively similar across studies. It was the 2D:4D values for the heterosexual participants that varied most, particularly between the USA and the British studies, and these were responsible for many of the discrepancies in the conclusions across studies. The constancy of the 2D:4D ratio for the White homosexuals did not appear to extend to homosexuals of three other ethnicities, and there were also subpopulation differences related to right or left hands.