Transcript for the Piece Audio version of Menstruation and the female voices
Host intro: The human voice can express many things. It can convey information and emotion… it can make music… and if you believe the results of recent studies in Germany and the United States, a woman’s voice can signal – well – we’ll let reporter Ari Daniel Shapiro explain the rest.
Ari: In a lot of animals, females make it abundantly clear when they’re ovulating – that is, when they can get pregnant. Female cats go into heat.
But in humans the signs aren’t as obvious.
Ari: It was thought to be concealed – that is, unnoticeable – says Julia Fischer.
She’s a researcher at the German Primate Center at Göttingen University.
But Fischer and a group of international colleagues wondered whether women might give off subtle cues when they’re most fertile. Specifically –
Ari: In other words, might a woman’s voice change throughout her menstrual cycle. So they recruited young German women for an unusual study.
Repeatedly, over one menstrual cycle, each woman recorded a series of vowel sounds like this:
Ari: Meanwhile, the women had to follow a strict protocol. Every morning, they’d get up, drink a glass of water, go to the bathroom –
Ari: That’s right – freeze the urine. And then, a research assistant would come by to collect the frozen urine later that day.
The urine helped Fischer and her team monitor the hormones and track each woman’s menstrual cycle. And when they compared the hormone data to the voice recordings, they found something interesting. The pitch of the vowels got a little bit lower over the course of the month.
Ari: So the women’s voices grew deeper when they were most fertile.
Now the shift is subtle but it is audible.
Here’s one woman recorded at the beginning of her menstrual cycle and then again during ovulation.
Ari: Fischer suspects the shift in pitch is due to sex hormones that cause the vocal cords to swell.
And she says there may be an evolutionary explanation as well.
The slight deepening of the female voice may signal to a male partner that – well –it’s time to procreate.
Fischer says the effect is likely subconscious… but the huskiness of the female voice at the time of ovulation may make a man more amorous.
In fact, that hypothesis was supported by another recent study.
Evolutionary psychologist Gordon Gallup and a colleague from the University at Albany recorded the voices of young American women through their menstrual cycles. They asked other people to rate how attractive the voices were.
Ari: So perhaps human beings aren't that different from other animals after all. Females do signal their fertility - even if it's in ways that we notice only subconsciously.
But a third study has recently muddied the waters a bit.
Scientists at UCLA asked women to read a sentence at a low fertility phase of their menstrual cycle.
Ari: And then again, close to ovulation:
Ari: In this case, the women’s voices went UP in pitch as they became more fertile.
Julia Fischer, who ran the study in Germany, says it’s not clear why there’s this difference with American voices going higher in pitch and German voices going lower.
But she says culture might play a role.
In Germany, when women signal that it’s time to make babies… they may emulate Marlene Dietrich.
In America… they might copy Marilyn Monroe.
For “The World,” I’m Ari Daniel Shapiro.
