London, May 1 (UNI) Women's voices become more seductive when they are most likely to conceive, according to a new study.
Researchers found that the female voice altered according to the time of the month.
They recorded women counting from one to 10 at different stages of the menstrual cycle, then played the voices back at random to a group of students.
Both men and women judged the voices to be most luring when they were recorded at periods of peak fertility and less attractive during non-fertile periods.
''The results are in line with evidence that the female voice box, or larynx, is under the influence of sex hormones,'' the scientists reported.
The study, carried out by Gordon Gallup and Nathan Pipitone at the State University of New York at Albany, adds weight to the theory that women give off fertility signals at certain times of the month, as animals do when they are ''in heat''.
Mr Gallup said it was not just men who have learnt to spot barely perceptible changes in women's voices; women could also notice the effect, perhaps to monitor the competition.
Previous work came to similar conclusions about women's voices.
Last year, a team based at the University of New Mexico, Albuquerque, found that lap dancers earned more in tips on their fertile days.
''The voice changes might explain some of the shift in lap dancer tip earnings,'' said Geoffrey Miller, who led the researchers.
''Dancers certainly chat with their customers,'' he added.
However, he pointed out that visual attractiveness also appeared to change during the menstrual cycle. ''Voice quality is unlikely to be the whole story,'' the Daily telegraph quoted him as saying.
Another team from the University of California, Los Angeles, found that vocal pitch could also play an important role in indicating fertility.
One of the scientists, Martie Haselton, said, ''We have found that voices are higher in pitch on high-fertility days of the cycle.'' UNI XC RJ KN1656