D. Mcfadden, A MASCULINIZING EFFECT ON THE AUDITORY SYSTEMS OF HUMAN FEMALES HAVING MALE CO-TWINS, Proceedings of the National Academy of Sciences of the United Statesof America, 90(24), 1993, pp. 11900-11904
Spontaneous otoacoustic emissions (SOAEs) are continuous, essentially
tonal sounds that are produced by many normal-hearing cochleas. In hum
ans, females generally exhibit more SOAEs than males, a sex difference
that exists from birth. However, it is shown here that females having
male co-twins [opposite-sex dizygotic (OSDZ) females] exhibit about h
alf the average number of SOAEs per ear observed in same-sex female tw
ins or female non-twins. Indeed, the average in OSDZ females is about
the same as that seen in males-twins or non-twins. The explanation off
ered here is that prenatal exposure to high levels of androgens has pr
oduced a masculinizing effect on the auditory systems of these OSDZ fe
males. Prenatal masculinizing effects have long been recognized in cer
tain litter-bearing mammals, but their existence in humans is not well
-studied.