Gender identity: Girls and boys sound differently as early as 5 years old

DAVIS, Calif. — The sound of a child’s voice can indicate their gender starting at age five, scientists say. The way children speak contains clues about their gender, but these are learned from a young age rather than based on physical differences when they hit puberty, according to a recent study.

Compared to adults, the voices of young boys and girls are very similar until they develop anatomical differences. But now, researchers report that people can identify gender by the sound of a child’s voice well before their body starts to change at around age 11 or 12.

Researchers created a database of speech samples from children ages 5 to 18 to see how their voices changed over time. Listeners were asked to assess speakers’ physical characteristics, including gender, age, and height based on the pitch and resonance of their voice. They were able to identify the gender of children as young as five by simply listening to their voices, the researchers found.

“This is well before there are any anatomical differences between speakers and before there are any reliable differences in pitch or resonance. Based on this, we conclude that when the gender of individual children can be readily identified, it is because of differences in their behavior, in their manner of speaking, rather than because of their anatomy,” study co-author Dr. Santiago Barreda, from the University of California, Davis, says in a statement.

The listeners’ ability to identify the speakers’ gender improved when they listened to sentences rather than syllables. “Resonance is related to speaker height — think violin versus cello — and is a reliable indicator of overall body size. Apart from these basic cues, there are other more subtle cues related to behavior and the way a person ‘chooses’ to speak, rather than strictly depending on the speaker’s anatomy,” adds Dr. Barreda, who co-authored the paper along with Peter Assmann, from the University of Texas at Dallas.

Listeners also automatically pictured the speakers’ age and size when guessing their gender.

“Essentially, there is too much uncertainty in the speech signal to treat age, gender, and size as independent decisions. One way to resolve this is to consider, for example, what do eleven-year-old boys sound like, rather than what do males sound like and what do eleven-year-olds sound like, as if these were independent questions,” says Dr. Barreda.

The findings suggest gender differences in the way people speak are not based on physical differences between men and women but are learned from a young age. “In other words, gender information in speech can be largely based on performance rather than on physical differences between male and female speakers. If gendered speech followed necessarily from speaker anatomy, there would be no basis to reliably identify the gender of little girls and boys,” Barreda concludes.

The findings are published in the Journal of the Acoustical Society of America.

South West News Service writer Tom Campbell contributed to this report.