AUSTIN, TexasBuilding on findings announced a year ago, a University of Texas at Austin research team has uncovered additional evidence that the inner ears of lesbians and bisexual women behave differently from those of heterosexual women.
The new findings are documented in the April issue of The Journal of the Acoustical Society of America in an article written by experimental psychology professor Dr. Dennis McFadden and research associate Edward Pasanen.
"The human ear produces sounds, as well as receiving and processing sounds," McFadden said. One type of these ear-generated sounds is known as spontaneous otoacoustic emissions or SOAEs. SOAEs are like weak pure tones that are continuously emitted by the inner ear. They are typically inaudible to their owners but can be detected by small, sensitive microphones inserted in the ear canal.
SOAEs are more common and stronger in women and girls than in men and boys. When McFaddenÌs research team measured the SOAEs of 60 homosexual and bisexual women, they found them to be both significantly less numerous and weaker than the SOAEs of the 57 heterosexual women also tested.
The homosexual and bisexual women were intermediate to heterosexual females and heterosexual males.
In March 1998, McFadden and Pasanen reported that a different form of otoacoustic emission (an echo-like sound called the click-evoked otoacoustic emission or CEOAE) produced by the inner ears of homosexual and bisexual women also is weaker than those produced by heterosexual women.
"We see the SOAE results to be a strong confirmation of the earlier CEOAE results," said McFadden. "They support the conclusion that the inner ears of heterosexual and nonheterosexual women are different. The challenge now is to determine why they are different.
"A likely explanation of homosexuality in women is that they prefer women as sex partners because one or more brain sites have been "masculinized" at some point in development, either before or after birth," he said. "Our findings suggest that the inner ear may be masculinized by those same processes."
McFadden emphasized that his findings represent group differences.
"The number and strength of SOAEs vary so greatly across individuals that it would be essentially impossible to determine whether an individual woman was homosexual or heterosexual by studying the tiny sounds emitted by her ear," he said.
"We hope this second study will reduce any lingering doubts among auditory scientists that there is a difference in the inner ears of heterosexual and nonheterosexual women," McFadden said.
For more information on the research, contact McFadden at (512) 471-4324.