The social and biological factors that affect a voice's gender

PROBLEM: If a women were involved in a particularly complex prank call that involved her being mistaken as male, or if -- as is more clinically applicable -- she were undergoing gender reassignment surgery and wanted her voice to change accordingly, she would likely speak at a lower pitch. In the second instance, testosterone treatment might be used to achieve this effect. But what actually makes us perceive a voice as belonging to a man or a woman?

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METHODOLOGY: A University of Colorado Boulder researcher recorded the voices of 15 transgender men and recorded the precise frequency at which they spoke. Lower frequencies, he assumed, would be perceived as more male. To determine precisely how low they needed to be, he manipulated the recordings on a sliding scale of frequencies and played them for a group of ten listeners, who were asked to identify each speaker's gender.

RESULTS: There didn't turn out to be one specific pitch at which voices went from being heard as male instead of female. Instead, gender perception depended more on the frequency at which the speakers pronounced their "s" sounds. For example, two speakers, "Joe" and "Kam," spoke at the same frequency, but with different "s" pitches. All of the listeners identified the former as male and the latter as female.

Aside from pitch, resonance (whether the speakers had what's commonly referred to as a "chest" or "head" voice) also affected the listeners' perceptions of gender.

IMPLICATIONS: How we pronounce "s" sounds and vocal resonance aren't completely inherent to being male or female; instead, we learn to manipulate both. For those looking to transition between genders, vocal training may turn out to be just as helpful as testosterone treatment.

The full study was presented at the annual meeting of the Linguistic Society of America in Boston.