By Russell Strause, MS-CCC, SLP
Have you ever wondered why adults talk to babies as if they were one? Have you caught yourself exaggerating your speech sometimes to the point where you’re almost singing? Have you ever heard the terms ‘motherese’ or ‘parentese’ before? This seemingly strange phenomenon is actually supported by years of science and observed across all regions and cultures. It is sometimes referred to as infant- or child-directed speech. And although using “baby talk” may seem counterintuitive to teaching your toddler to speak like an adult, it actually has some surprising effects like grabbing an infant’s attention sooner and keeping it longer, as well as providing examples that are easier to copy.
In a recent study by Linda Polk et al., “Setting the Stage for Speech production: Infants Prefer Listening To Speech Sounds With Infant Vocal Resonances, 2022” researchers tested whether infants prefer listening to speech sounds that resemble their own compared to adult productions. Polk et al. did so by manipulating sounds, i.e., the fundamental frequency of vowels, so they sound as if they came from an infant’s vocal tract rather than the adult’s vocal tract. Building on previous research that found children ages 4-6 months prefer listening to infant speech sounds. Polk et al. found children ages 6-8 months have “a robust and distinct preference for speech with resonances specifying a vocal tract that is similar in size and length to their own…[which] 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 that an early link between speech production and perception in infants exists” (Polk et al.). One interesting fact about this study is older infants, 6-8 months, paid more attention for a longer period of time to sounds that appeared to come from a child.
To support this idea, a study done by Princeton, “Uncovering the sounds of ‘motherese,’ baby talk across languages” 2017, found similar results while recording 12 English-speaking mothers playing with or reading to their 7–12-month-old infants. The researchers found that all mothers speaking to infants changed the timbre, or the uniqueness of their voice to support language development and encourage imitation. Timbre can be thought of as the distinct quality of a sound. For example, a trumpet and a piano can play the same key but sound distinctly different. So, by changing the timbre of the mothers’ voices, researchers were able to see that adult-directed and infant-directed speech have “significantly different fingerprints.” Since the original study, it has been replicated in different regions and infant-directed speech is “seen across languages from around the world: Cantonese, French, German, Hebrew, Hungarian, Mandarin, Polish, Russian, and Spanish” (Liz Fuller-Wright).
Another study by Lloyd-Fox et al. 2015 reported that “infant-directed speech accompanied by direct eye contact has a special effect on the brain…[and] when adults communicated face-to-face using infant-directed speech, babies experience enhanced activity in brain regions associated with processing auditory messages. Similar attempts using every day, adult speech had no such effect” (Lloyd-Fox et al 2015). They found children tend to pay more attention and retain more language when adults use more melodic and rhythmic properties as well as using developmentally appropriate sounds of the target language. Infant-directed speech has been shown to aid in an infant’s ability to discriminate between different speech sounds, highlight emotions effectively, detect the boundaries between words in connected speech, and recognize distinct clauses in a stream of speech.
Studies were also done with bilingual infants. For example, researchers Huei-Mei Liu et Al. performed an experiment on Mandarin-speaking mother-infant pairs in Taiwan (Lui et al 2003). Children aged 6-12 months were exposed to a background sound such as a Mandarin Chinese word repeated over a loudspeaker many times. Then researchers used a minimal-pair word, i.e., one that differs by a single consonant like “cat” and “hat”, to see if infants would recognize the change. If the infants recognized the change, then the infant would turn their heads toward the loudspeaker. The researchers assessed each baby’s speech perception skills in 30 trials and recorded their results before analyzing the infant-directed speech patterns of the baby’s mother. They, too, found a strong correlation between a mother’s baby-talk and their baby’s speech perception skills. And if this wasn’t interesting enough, it should be noted that infant directed speech is not only useful for infants but adults as well. For example, some experiments have shown that adults listening to foreign languages are better able to pick up on a speaker’s emotions when the speaker is using infant-directed speech.
However, even though there is not a direct correlation between infant directed speech and increased language development, it still proves useful for late talkers in clinical settings. One characteristic that parents may recognize in speech therapy sessions is the way our therapists communicate with their children. The strategies include:
- Simplifying language to one word or short sentences
- Slowing speech
- Elongating the vowels in words
- Talking at a higher pitch with more “peaks and valleys”
- Animating or over-exaggerating emotions with language
- Repeating often
If your toddler seems to be acquiring language slowly or not at the same rate as their peers, then these strategies may help get the ball rolling. However, these are only tips to facilitate language development and should not be a replacement for traditional diagnoses and treatment of speech delays or disorders. If you have any questions, please contact Uplift Therapy Center today with questions about your child’s language development.