A doo doo doo, a da da da, besides a song by The Police, it’s the kind of sounds we often make to babies. And even when we say normal words, we will often use a higher pitch, a slower speed and use an exaggerated pronunciation. As if we are teaching them words? Exactly.
From the press release:
The way we instinctively speak to babies — higher pitch, slower speed, exaggerated pronunciation — not only appeals to them, but likely helps them learn to understand what we’re saying. New research from the University of Florida suggests that baby talk can have another, previously unknown benefit: helping babies learn to produce their own speech. By mimicking the sound of a smaller vocal tract, the researchers think, we’re cluing babies in to how the words should sound coming out of their own mouths.
“It seems to stimulate motor production of speech, not just the perception of speech,” said Matthew Masapollo, Ph.D., an assistant professor in UF’s Department of Speech, Language, and Hearing Sciences and director of the UF Laboratory for the Study of Cognition, Action, and Perception of Speech in the College of Public Health and Health Professions. “It’s not just goo-goo ga-ga.”
In the study, the researchers changed the frequency sounds to mimic either an infant or adult vocal tract, and then tested how infants reacted. Six- to eight-month-old babies “displayed a robust and distinct preference for speech with resonances specifying a vocal tract that is similar in size and length to their own,” they wrote.
Four- to six-month old babies didn’t have that preference, suggesting that older babies’ dawning ability to control their voices and make words out of babble could be what makes the infant-like sounds more appealing.
Though baby talk may sound simple, it’s accomplishing a lot, says coauthor Linda Polka, Ph.D., of McGill University.
“We’re trying to engage with the infant to show them something about speech production,” she said. “We’re priming them to process their own voice.”
While parents are sometimes discouraged from engaging in baby talk, Masapollo and Polka’s research shows the patterns associated with that speaking style — which scientists call “infant-directed speech” — could be a key component in helping babies make words.
Abstract of the study:
Purpose: Current models of speech development argue for an early link between speech production and perception in infants. Recent data show that young infants (at 4–6 months) preferentially attend to speech sounds (vowels) with infant vocal properties compared to those with adult vocal properties, suggesting the presence of special “memory banks” for one’s own nascent speech-like productions. This study investigated whether the vocal resonances (formants) of the infant vocal tract are sufficient to elicit this preference and whether this perceptual bias changes with age and emerging vocal production skills.
Method: We selectively manipulated the fundamental frequency (f0) of vowels synthesized with formants specifying either an infant or adult vocal tract, and then tested the effects of those manipulations on the listening preferences of infants who were slightly older than those previously tested (at 6–8 months).
Results: Unlike findings with younger infants (at 4–6 months), slightly older infants in Experiment 1 displayed a robust preference for vowels with infant formants over adult formants when f0 was matched. The strength of this preference was also positively correlated with age among infants between 4 and 8 months. In Experiment 2, this preference favoring infant over adult formants was maintained when f0 values were modulated.
Conclusions: Infants between 6 and 8 months of age displayed a robust and distinct preference for speech with resonances specifying a vocal tract that is similar in size and length to their own. This finding, together with data indicating that this preference is not present in younger infants and appears to increase with age, suggests that nascent knowledge of the motor schema of the vocal tract may play a role in shaping this perceptual bias, lending support to current models of speech development.