Baby talk, also known as "motherese," has been recognized in a number of languages as a universal form of communication that mothers consistently use when speaking to their child, according to new research.
The study, published in the on Thursday, found that mothers use different timbres when talking to infants.
Timbre, not to be confused with pitch, refers to the unique quality of a sound, like the difference between musical instruments or if a voice is nasal versus hoarse.
The researchers at the Princeton Baby Laboratory recorded 12 English-speaking mothers while they played with and read to their infants and also while they talked with another adult.
After finding the mother's unique 鈥渧ocal fingerprint鈥�, the researchers found that a computer could reliably tell the difference between infant- and adult-directed speeches with only one second of recorded speech.
The same vocal change was noted across women speaking 10 different languages, including Spanish, Russian, Polish, Hungarian, German, French, Hebrew, Mandarin, and Cantonese.
鈥淲e found that mothers alter this basic quality of their voices when speaking to infants, and they do so in a highly consistent way across many diverse languages," study author Elise Piazza said in a statement.
The study didn鈥檛 look at dads, but Piazza said its likely fathers would show a similar shift in timbre.
While baby talk is not a new discovery, this is study is the first time a shift in timbre has been found.
鈥淭his is fascinating because clearly speakers are not aware of changing their timbre, and this new study shows that it is a highly reliable feature of the way we speak to babies," commented Jenny Saffran, a professor of psychology at the University of Wisconsin-Madison who was not involved in this research.
The U.S. researchers said the next step is to explore how the timbre shift helps infants in learning.
Previous research has suggested that changes in voice can help babies with learning language, engaging their emotions and highlighting the structure in language, so they can figure out syllables and sentences.
Piazza also said that her team鈥檚 technique for quantifying timbre could be used for other types of speech analysis.
"Our work also invites future explorations of how speakers adjust their timbre to accommodate a wide variety of audiences, such as political constituents, students and romantic partners," she said.
