Study Shows Women’s Voice Attractiveness Varies Across the Menstrual Cycle
University at Albany-SUNY researchers conclude that women at their most fertile point sound more appealing

Contact(s):  Catherine Herman (518) 956-8150, ([email protected])

ALBANY, N.Y. (May 13, 2008) -- In an article recently published in the journal Evolution and Human Behavior, University at Albany researchers Nate Pipitone and Gordon Gallup evaluate the affects of the menstrual cycle on voice attractiveness of females and conclude that a woman's voice can carry biological information that might be a factor in her sexual appeal.

The human larynx is a hormone-affected organ; its size and shape can be altered by varying levels of estrogen or testosterone.  Especially during puberty, pregnancy, and menopause, rising or falling hormone levels alter the larynx and produce vocal changes. With this in mind, the researchers surmized that voice can carry biological information, such as hormonal activity.  Other studies published previously in Evolution and Human Behavior and elsewhere show that both men and women attend to the characteristics of male voice in evaluating both mates and competitors. 

Hormones regulate voice
In their research, psychologists Pipitone and Gallup extend the focus by studying women’s voices and by focusing on shorter term, cyclic fluctuations.  Over their monthly cycle women’s hormones rise and fall in a patterned way.  As Pipitone and Gallup show, the rated attractiveness of their voices changes in parallel with these hormonal fluctuations. Using 51 female undergraduates from the University at Albany, Pipitone and Gallup collected four separate voice samples from each individual, at equally-spaced intervals during one complete menstrual cycle. For each voice sample, conception risk was calculated based on when in the woman’s cycle the sample was recorded.

As a control, every voice sample was kept as expressively neutral possible, with the subjects simply counting from one to ten.  In addition to voice samples, the researchers gathered information on the women’s age, number of current and lifetime sexual partners, and whether or not they were currently taking a hormonal contraceptive.

In order to measure the attractiveness of the voices, Pipitone and Gallup recruited 34 males and 32 females, who rated each voice sample for attractiveness on a 100-point scale. To provide statistical control the researchers randomized the order of the voice samples both by speaker and by cycle phase.

Both sexes perceive voice differences
For the naturally cycling females, voice attractiveness ratings increased with conception risk. For females taking hormonal contraceptives, which disrupt the normal cyclic changes in hormone levels, there was no correlation between voice attractiveness rating and menstrual cycle phase. Between the raters, there was no sex difference in their rating of voice attractiveness, indicating that both males and females perceive the voice differences.
 
The precise mechanism by which short-term hormonal changes alter the voice has not been measured; nor can the researchers say, at present, what vocal parameters are changing across the cycle. However, Pipitone and Gallup argue that, as hormone production varies across the menstrual cycle, perceivable vocal changes do occur. In the animal world, male macaques have been shown to distinguish and prefer calls of females in estrus over females who are less reproductively receptive. As Pipitone and Gallup state, “the basic underlying anatomy, acoustics, and central control over vocal tracts are similar between humans and other mammals, implying that our findings may not be unique to humans.”

Peaks at ovulation
Although some underlying mechanisms remain unclear, the fact that the observed changes in voice attractiveness across the menstrual cycle were limited to naturally cycling women suggests that hormones are indeed responsible.  The fact that attractiveness peaks near ovulation suggests that both women’s voices and listener’s perceptions have been shaped by evolution so as to maximize reproductive success.  Consistent with this interpretation, previous research published by Gallup and his colleagues in Evolution and Human Behavior has shown that females with attractive voices tend to have more accentuated hour glass figures (narrow waists and broad hips), they are more symmetrical (features on one side of the body more closely match those on the other), and they have more sex partners.

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