Princeton researchers have identified “a new cue that mothers implicitly use to support babies’ language learning,” said Elise Piazza, a postdoctoral research associate with the Princeton Neuroscience Institute (PNI). “We found for the first time that mothers shift their vocal timbre. (View Highlight)
the timbre shift was consistent across women who speak 10 languages, including English, and that the differences are strong enough to be reliably picked out by a machine learning algorithm. (View Highlight)
The scientists then quantified each mother’s vocal fingerprint — the overall statistical profile of her timbre — using a measure called the mel-frequency cepstrum. They found that adult-directed and infant-directed speech had significantly different fingerprints. “It’s so consistent across mothers,” said Piazza. “They all use the same kind of shift to go between those modes.” (View Highlight)
“We’ve known for a long time that adults change the way they speak when they are addressing babies,” said Jenny Saffran, a professor of psychology at the University of Wisconsin-Madison who was not involved in this research. “They speak more slowly, use shorter sentences, talk at a higher pitch and swoop their pitch up and down more often than when they are speaking to other adults.” What sets this work apart, Saffran explained, was that “this is the first study to ask whether [mothers] also change the timbre of their voice, manipulating the kinds of features that differentiate musical instruments from one another. This 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.” (View Highlight)
researchers found that this timbre shift between adult- and child-directed speech was “highly consistent” across languages from around the world: Cantonese, French, German, Hebrew, Hungarian, Mandarin, Polish, Russian and Spanish. These shifts in timbre may represent a universal form of communication with infants, said Piazza. (View Highlight)