From Reuters:

New research findings suggest that the sound of a person's voice may predict his or her level of sexual activity. ...

In the study, 149 men and women listened to recorded voices of anonymous individuals and rated the voices on a five-point scale, from "very unattractive" to "very attractive." ...

When the researchers compared voice ratings with sexual histories, they found that men and women whose voices were considered more attractive by opposite sex raters reported younger ages at first sexual intercourse, more sex partners and more sexual affairs than did those with less attractive voices.

Voice attractiveness predicted promiscuity in women better than did their waist-to-hip ratio, Hughes and her colleagues report in the September issue of Evolution and Human Behavior. Among men, however, the shoulder-to-hip ratio was a better predictor of promiscuity.

That said, not all women with attractive voices are promiscuous, but "promiscuous females tend to have more attractive voices," co-author Dr. Gordon G. Gallup Jr., of the University at Albany, State University of New York, told Reuters Health. ...

During human evolutionary history, voice may have also played a role in how men and women made reproductive-related decisions, particularly at nighttime, the report indicates.

"The sound of a person's voice could have become an important indicator of other biologically relevant information," Gallup Jr. said.