Want to sound more authoritative or hit those low notes in your signature song? Just have a baby. It worked for Adele and Kristen Bell, who have both noted that during and after pregnancy, their voices were lower.
Researchers at the University of Sussex in Britain may have an explanation. The investigators studied archive interview recordings of 20 mothers, including actresses, journalists, and singers, and compared them to a control group.
Working from more than 600 voice recordings, they were able to analyze voice pitch in the five years before and after pregnancy and found that on average, a woman’s voice after giving birth dropped by 5%, which amounts to 44 hertz, or two musical notes. It’s a noticeable difference, especially if you’re shooting to hit the low notes in an Oscar-winning theme song like Skyfall.
“When it comes to human voices, we can perceive pitch differences around 5 hertz in regular speech, so 44 hertz is a very salient difference,” lead author Dr. Kasia Pisanski said.
The experimental psychologist also notes that while singers have noticed their voices getting lower while pregnant, “the big drop actually happens after they give birth.” The new range typically lasts for about a year. The researchers don’t know why this happens, but hormone changes may be partly responsible.