Flirtation may seem largely visual - the preening, the coy eye contact - but voice plays a role, too.
Lowering your voice may be a means of demonstrating attraction, says Susan Hughes, assistant professor of psychology at Albright College in Reading, Pa., in a study, "Vocal and Physiological Changes in Response to the Physical Attractiveness of Controversial Partners," to be published in the fall by the Journal of Nonverbal Behavior.
"We found that both sexes used a lower-pitch voice and showed a higher level of physiological arousal when speaking to a more attractive opposite-sex target," she says.
The study examined 48 Albright students using Skype to leave scripted voice-messages while viewing a picture of a fictitious person "receiving" the message. The men and women the participants looked at varied in attractiveness.
Hughes - who expected that women would raise their voices to sound more feminine and attractive - was surprised.
"There appears to be a common stereotype in our culture that deems a sexy female voice as one that sounds husky, breathy, and lower-pitched," she says. "This suggests that the motivation to display a sexy/seductive female voice may conflict with the motivation to sound more feminine."
Female voice manipulation suggests that altering their tone may be a learned behavior based on sexual voice stereotypes rather than actual vocal characteristics of attractiveness. "When a woman naturally lowers her voice, it may be perceived as her attempt to sound more seductive or attractive, and therefore serves as a signal of her romantic interest," she adds.
Their research also measured people's awareness of the changes in others' voices.
"These findings may have implications for the important role voice plays in mate selection and attraction," she says. "If people can perceive changes in others' voices when speaking to attractive individuals, this perception may be adaptive for identifying interested potential mates, detecting partner interest in others, and possible detection of partner infidelity."
Says Hughes, "The sound of a voice can communicate a wealth of biologically and socially important information."