Mating Calls: Does a Woman's Voice Hint at Ovulation during Her Menstrual Cycle?

Past studies have suggested that a woman's menstrual cycle can affect her voice during ovulation as a mating call to men indicating that biologically her body is receptive to reproduction. These studies have focused on two phases during the menstrual cycle: high conception phase and low conception phase. Recent research, however, challenges the suggestion and looks at changes in a woman’s voice throughout the entire menstrual cycle phases as reported in a recent article published in the journal PLoS ONE.

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In the world of frogs, it is typically only the male who gives out a mating call to the female. Females are generally limited to a reciprocation call or a ”release call,” which basically says, “Get off my back, I’m not receptive right now,” during the act of amplexus. Amplexus is the mating embrace of a frog or toad during which eggs are shed into the water just before a male releases his sperm into the water to fertilize the eggs. Male frogs, by the way, also have a release call that is vocalized when one male mistakenly commits amplexus with another male.

However, in Borneo there is one species of fanged frog named Rana blythii - in which the male lacks an advertisement call - consisting of females who have a male-like advertisement call. Studies of the female frog in this species revealed that the female advertisement call is a true female mating call associated with increased levels of sex hormones during her reproductive cycle.

While we cannot see into the mind of a frog, the general scientific consensus is that a female mating call is believed to be primarily a means of attracting males. However, another theory is that since the male of this species is aggressively territorial, the female may just be signaling ahead that a receptive female is entering his domain as opposed to an interloping male ready for a fight.

A little higher up the evolutionary ladder, however, the idea of women signaling men—consciously or not—their reproductive status has met some interesting studies. The more common studies have been about silent signals in the form of pheromones linked to changes in hormonal levels during a woman’s monthly cycle.

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In the PLoS ONE article, the authors are challenging the data from previous studies that suggest a woman’s voice also offers clues about where she is in her reproductive cycle. In particular, the time when her ovaries are about to release an egg or two.

In the study, the authors monitor the hormonal levels, measure and perform acoustic analysis of voice tone changes, and rank male perceptions toward the attractiveness of a woman’s voice throughout an entire cycle. What the researchers found was that a woman’s tone is highest during the pre-ovulatory phase and then lowers on the day of ovulation. Furthermore, the higher tone returns during the post-ovulatory phase, which makes tonal quality in a voice an unreliable indicator of ovulation.

What they did find, however, were significant changes in voice characteristics during the time of menstruation. They authors state that these changes were particularly in the noise-to-harmonic ratio (NHR) and degree of unvoiceness (DUV). In other words, the voices were more harsh than normal during menstruation—a short pause for private thoughts is permitted here.

And, when it came to when during a woman’s cycle that a man finds her voice to be “attractive,” their results showed a slight preference to pre-ovulation phase voices over ovulation phase voices.

The overall conclusion from the study is that there is no clear indication that a woman’s voice indicates when she is ovulating. Unless of course she calls you on the phone with a thermometer in her mouth, saying that she is ovulating, and asking you where you are right now. Then, the signal is pretty clear.

Source: “Do Women's Voices Provide Cues of the Likelihood of Ovulation? The Importance of Sampling Regime” PLoS ONE 6(9): e24490. doi:10.1371/journal.pone.0024490

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