Researchers have found that mothers actually change the timbre of their voices when they speak to their babies in "motherese." It is a form of speech mothers use to communicate with infants that is consistent across different languages from around the world.

'Motherese' Or 'Baby Talk'

Anyone with children or has ever been with someone who has children might agree that mothers tend to talk to their children in a manner of speaking called "motherese." It is basically the way mothers talk to their infants that is often musical or exaggerated in manner, and is not a manner of speaking that is used for conversing with adults. Such a manner of speaking is often referred to as simple "baby talk," and is not particularly looked into as an actual form of speech with structure.

A new research published in the journal Current Biology found that mothers change the timbre of their voices when they talk to infants. In fact, the shift in timbre is so distinct that a machine learning algorithm can distinguish whether the mother is talking to an infant or an adult.

Speaking To Adults And Speaking To Infants

In order to gather their findings, the researchers enlisted 12 English-speaking mothers to talk to their 7- to 12-month-old infants, and to an adult experimenter. Using a mel-frequency cepstrum, the researchers found that among all the participants, speech directed at infants and speech directed at adults had significantly distinct vocal fingerprints.

By this, the researchers mean that mothers deliberately shift the timbre or unique sound of their voices when they switch between talking to adults and when they are talking to infants. The shift is so distinct that the algorithm can determine whether the speech is infant-directed or adult-directed even with just a one-second recording.

Motherese Across The World

With the timbre shift already established, the researchers then gathered 12 more participants, this time mothers who do not speak English as their first language. All 12 spoke in their native language during their recordings, and amazingly, the researchers garnered the same response.

In fact, they found that the timbre shift between infant-directed and adult-directed speech is highly consistent across 10 languages. These include English, Cantonese, Mandarin, French, German, Hungarian, Hebrew, Polish, Spanish and Russian.

Fathers and other caregivers were not included in the study.

Why Is This Important?

While baby talk isn't exactly a new concept, using such speech manners with infants has been shown to play an important role in infant development. It helps their language learning, helps them to decode sentences and syllables, and engages the infants' basic emotions.

Moreover, the researchers believe that their manner of identifying and quantifying timbre shifts could also be used to identify other types of speech analysis.

"Our findings could enable speech recognition software to rapidly identify this speech mode across languages. 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," says Elise Piazza of Princeton Baby Lab, co-author of the study.