Pregnancy brings many changes to the female body, but did you know that tone of voice is one of them?
Let’s face it, pregnancy alters many body systems. From food preferences to smell aversions, the hormones of pregnancy have a mind of their own. Some of the changes that occur during pregnancy are temporary, while others are long-lasting. For example, many women share the experience of needing to go up a size on their favorite shoes after pregnancy.
One of the lesser-known side-effects of pregnancy is voice alterations. In 2013, Kristen Bell began discussing how her voice changed in her recent pregnancy, which required her to re-record her lines in the film Frozen.
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“The pregnancy did change my voice. It made it deeper, there were more womanly tones when I did one recording while I was extremely pregnant. After I had the baby, I had to go back and re-record those lines so they matched. There was something different about my voice.” Bell told People magazine.
Researchers at the University of Sussex’s Voice Lab have confirmed what Bell, and many others, experience. Their study revealed that the pitch of a new mother’s voice drops by two piano notes, as well as becomes more monotonous, after the birth of her first baby.
“Our results demonstrate that pregnancy has a transient and perceptually salient masculinizing effect on women’s voices,” the authors said.
The study, published this month in Evolution & Human Behavior, used over 600 voice recordings from 20 mothers and 20 women who had never had children. Participants included singers, journalists, reporters, and actresses. The voices were analyzed using a program called Praat.
Results of the study showed that the average mother’s mean and minimum voice pitch dropped by 14 Hertz, or 1.3 semitones, after they gave birth. Also, her maximum voice pitch fell by 44 Hertz, confirming that singers such as Adele were right on when they said that they could no longer reach the high notes after becoming moms.
The scientists did not study the reasons behind the voice changes but suggest that hormonal fluctuations are likely to blame. The good news is that the changes only lasted for about a year, after which the new mom’s voices return to pre-pregnancy levels.
The authors also suggest that faced with the new role of parenting, a mother might subconsciously change her voice.
“This effect could also be behavioral. Research has already shown that people with low-pitched voices are typically judged to be more competent, mature, and dominant, so it could be that women are modulating their own voices to sound more authoritative, faced with the new challenges of parenting,” they said.