The next time you hear a baby cry, take a good listen. It might tell you something about how its voice will sound decades later as an adult.
Research has already shown that the pitch of a person’s voice stays basically the same during adulthood and that how we sound as adults may be determined before puberty. A recent study indicated that the pitch of a boy’s voice at age 7 can mostly predict what he will sound like as an adult.
So when do our voices start emerging? One group of researchers hypothesized that differences in pitch would emerge very early — even in babies who haven’t yet learned how to speak.
Now, their new research — published last week in the journal Biology Letters — indicates that the pitch of babies’ cries at 4 months old may predict the pitch of their speech at age 5. In fact, the researchers said, the differences identifiable in babies’ whines can explain 41 percent of the differences in voice pitch that appear by age 5.
Taken together with previous studies, they said, this suggests a discovery that may be surprising: that “a substantial proportion” of the difference between how we sound in adulthood may be traceable back to the time we spend in utero. Indeed, they said, that would explain why there are differences in baby screams so soon after birth.
“In utero, you have a lot of different things that can alter and impact your life — not only as a baby, but also at an adult stage,” said Nicolas Mathevon, a professor who studies animal behavior at the University of Lyon in France and was one of the authors of the study.
“This explains a lot, but not all,” he added. “It’s only half the story I would say.” As for the rest? “We don’t know,” he said.
Carolyn Hodges, an assistant professor of anthropology at Boston University who was not involved in the study, said research had shown that voice pitch affects our impressions of a person’s physical and social dominance, attractiveness and trust, which can have real-world consequences.
“There aren’t many studies that address these questions, so that makes this research especially intriguing,” she said, noting that it “suggests that individual differences in voice pitch may have their origins very, very early in development.”
To conduct their study, the team of five bioacoustic researchers recorded the voices of 15 French children — six girls and nine boys — from 4 to 5 years old. In each case, they had recordings of what they called “mild discomfort cries” that were obtained when the same children were from 2 to 5 months old.
Previous research has shown that although adult human voices range significantly based on sex, there are no sex differences in the pitch of babies’ cries or the speech of children before puberty.
The new study reinforced those findings and also found that the pitch of babies’ cries at 4 months old was “a significant and substantial predictor of the pitch of their speech” at age 5.
Still, researchers cautioned that their sample size was small and noted that “further investigations involving a larger sample” — especially one with more females — were needed to confirm the correlations they found.
Professor Mathevon said the researchers had begun their study with more children but lost contact with some families over time.
He also emphasized that the children studied were all French, making it a culturally homogeneous group. It would have been better to have children from a variety of backgrounds, he said.
“It’s extremely difficult to follow a group of children like this,” he said.
Ms. Hodges agreed that getting longitudinal data of this sort was difficult.
“With small sample sizes, there is a danger that it is not representative of the population as a whole,” she said. “However, if it is representative, then the relationship is likely a strong and robust one.”