Studies have previously claimed that women become subtly different when they are ovulating.
By talking, dressing, acting and even smelling more alluring, women might increase their chances of having sex when they are most likely to conceive, the reports said.
A new study has offered another view. Focusing purely on the way women talk over the course of a month, the researchers found that the female voice is not a reliable predictor of ovulation, reports ABC Science.
Those results support the theory that, in our species, women tend to conceal the timing of their fertility so that men will be more likely to stick with them for the long haul.
"It's just really interesting to find out why we are the way we are," ABC Science quoted Professor Julia Fischer, a primatologist and communications researcher at the German Primate Center in G?ttingen, as saying.
"Why do men go for certain women? And why are humans generally monogamous whereas monkeys aren't?"
Fischer and colleagues studied 23 German-speaking women over the course of a full month. Every day during the cycle, the researchers collected urine samples for hormone analysis, and they asked the women to record themselves talking freely about anything.
Later, they presented pairs of voices to British men who did not understand German, and asked them to pick the voice they liked better.
Analyses showed that vowel sounds became slightly lower as ovulation approached for women, though the statistics were not significant and the change would likely be imperceptible to a listener, says Fischer.
The new study also found a rise in the pitch of women's free speech as ovulation approached, just like in the study published last year. But on the day of ovulation, their voices dipped again.
The only reliable trend was during menstruation, when voices generally became more hoarse.
The study has been published in the journal PLoS One.