Listen closely to the pitch of her voice, and that woman might offer up a clue: Is her voice higher than usual? Maybe it's that fertile time of month. Lower-than-usual? Not-so-fertile time.
Such are the findings of Gregory Bryant and Martie Haselton, both of UCLA, after taking recordings of 69 women speaking simple sentences during fertile and non-fertile times of their cycle (as verified by hormone tests), with the most pronounced change occurring two days before ovulation. In their report, published in the journal Biology Letters, the two scientists interpret this change as being evolutionarily useful — it's an "enhanced femininity" signal, which might make mating more likely at the approach of ovulation, a time more likely to result in a pregnancy.
Sometimes, you have to wonder why people set out to do the experiments they do. (They had some audio software? There were a lot of women around?) But this isn't the first ovulation-cue research that Haselton has done.
In fact, as the study's very first paragraph begins (drawing us in nicely, I might add), studies have already reported other changes to occur during women's fertile periods: of attractiveness of scent, attention to clothes, flirtatiousness, degree of jealousy of the male mate. "One study showed that exotic dancers earned the most tips when nearest to ovulation," the paper continues.
And there's more! Cows have vocal changes when they're fertile! So do elephants.
Women's voices get hoarser around menstruation, some studies find.
Read more about the scientists' work — including original papers on the shrill-voice and attractive-clothes research — at Haselton's website.
— Rosie Mestel