A new research suggests men can actually tell from a woman’s voice when she is having her period.
In a study, published in the journal Ethology, psychologists asked three groups of men to listen to voice recordings of ten women who counted from one to five – at four different points over their menstrual cycle.
All four recordings were played in a random order – and then the first group of men were asked to guess which were made while the women were on their period, Popular Science reported.
The tests, conducted by Nathan Pipitone at Adams State College and Gordon Gallup, from SUNY-Albany, revealed that the men were correct 35% of the time – described as a “significant” result.
A 2008 study run by the two scientists had already shown that men find the voices of ovulating women more attractive than voice recordings at other points in their period cycle.
So to update their research, the two scientists swapped the recordings which were nearest to ovulation with those from a less fertile day.
The second group in the new study still spotted the voice during menstruation 34% of the time.
In fact, Nathan Pipitone and Gordon Gallup said all three group pinpointed the “period” voices more than any other recordings.
In another experiment, a separate group of men – who were not told the study had anything to do with menstruation – were asked to pick out the most “unattractive” voice.
In 34% of cases, they chose the menstrual recording – significantly more than was predicted by chance.
According to the men taking part in the experiments, they could tell the women were menstruating by four key indicators in the recordings: mood (bad v good); quality (harsh v smooth); pitch (low v high); and speed (slow v fast).
Some said that the menstrual recordings appeared lower in pitch, quality and mood.
In evolutionary terms, an aversion to menstruation – whether conscious or subconscious – is logical because males will seek females who are ovulating in order to pass on their genes.
Nathan Pipitone said: “The men seemed to determine menstrual voices by picking the most unattractive voice.”
He added that it is hormones that give the women away, by inducing vocal change.
“Vocal production is closely tied to our biology. For example, cells from the larynx and vagina are very similar and show similar hormone receptors,” Nathan Pipitone said.
As a result, according to Gordon Gallup: “The sound of a person’s voice contains a surprising amount of reproductively relevant information.”
Evidence has already shown that men subconsciously judge where a woman is in her menstrual cycle.
Lap dancers make 80% more money in tips when they’re ovulating compared to when they’re menstruating, the journal Evolution & Human Behaviour reported in 2007.
In 2011, a German study showed the voices of women on their periods tend to be “heavier and less harmonic”, according to Wired.