Baby

My brother-in-law had a lovely experience when his first daughter, Keegan, was born. She was crying, until he sang the song he had been serenading his wife’s belly with for several weeks. Keegan quieted down right away and turned towards the sound.

It seemed to Paul that his baby recognized that song. But did she really?

It’s entirely possible. Linda Polka, associate professor in the School of Communication Sciences and Disorders at McGill University, explains that unlike vision, a baby’s auditory system is fully developed at birth. In fact, newborns have been hearing for three months already.

“There is quite a bit of evidence that babies begin to learn from what they hear in the womb,” says Polka. “They will prefer their mother’s voice to another woman’s voice shortly after birth. There is also research showing that if the mother has repeatedly read a story or sung a song in the last trimester, her newborn will prefer that story or song over another one.”

The research that is helping unravel how babies learn to understand, and speak, a language is largely based on “listening preference” studies. It’s founded on the discovery that babies will pay attention longer to stimuli — certain words or sounds, for example — that they recognize.

What that research reveals is that long before babies speak their first word, a complex learning process is in play. Here are just a few stops along the way:

Discriminating Sounds
At birth, babies are ready to learn any language. “At this point they are not selective,” says Polka. “It doesn’t matter if that consonant or vowel is being used in their own language, they will discriminate it from other sounds. For example, a Japanese baby will tell the difference between the English R and L sound, even though his parents may have a hard time telling those apart.”

By ten or 12 months, though, babies may no longer pay attention to distinctions that do not occur in their mother tongue. As Polka’s co-worker, Megha Sundara, explains, “It seems like they are learning to tune out the things that don’t make a meaningful difference in their language, and tune in to the sounds that are relevant.”

In the first year, babies also learn a lot about the common sound patterns in their language, says Polka. “If there is a certain sequence of sounds that occurs regularly in their language, they’ll recognize that over some sequence that is less common.”

Rhythm
Your baby is born knowing other elements of your language. “We know that newborns will definitely distinguish the rhythm of their mother tongue from another,” says Polka.

That knowledge is reflected in their babbling: “When they start to babble, they become little rhythm generators,” says Polka. “They’ll say bababa-babababa.” But research comparing babies in French- and English-speaking families shows that the rhythm of their babbling soon echoes that of their parents’ language. For example, French has more multi-syllabic words than English, and “French babies seem to babble in multi-syllabic strings more.” They even put the stress in the right place: “If they produce a two-syllable babble, it will sound like there’s more stress on the second syllable with the French babies, while English babies seem to put more stress on the first syllable.” That just happens to imitate the most common pattern in their respective languages.

It’s this sensitivity to rhythm that helps babies with one of their toughest language challenges:

Discriminating Words
We automatically break speech into units called words, but if you really listen you realize that in normal speech the words all flow together: “Howareyou, Bill?” It’s been a big problem in the creation of machines that can recognize speech, says Polka: “The machine does not know where words begin and end.” So how do babies figure it out?

It starts quite early, says Polka. “One study showed that babies will prefer to listen to their own name over another’s at 4½ months — even if the other name has the same general rhythm.” That means they recognize “not just the pattern of it, but the details,” Sundara points out. “They know what their name sounds like.”

By 7½ months, babies can pick out a word they’ve heard repeatedly in a story. Now here’s where rhythm enters into it. Seven-month-old babies can also detect a two-syllable word in a story — but only if it has the “right” stress pattern. If the baby is learning English, the stress has to be on the first syllable: She will pick out “doctor,” but won’t recognize “guitar” until she’s older, around ten months. In French, the reverse is true. So it’s understanding the intonation of their own language that helps babies find the breaks between words.

“What babies learning English seem to know is that ‘If I hear a stressed syllable, that’s the beginning of a word,’” explains Polka. “Sometimes they’ll do that and make mistakes — for example, if they hear a story where they hear ‘the guitar is…’ they think ‘taris’ is the word. When they get a little older they have other kinds of information that help them figure it out.”

Which brings back a sudden memory. When they first began to talk, all my kids called my husband’s guitar his ’tar. One said ’chine for machine. They started the word at the stressed syllable. And when the stress came on the first syllable, both parts of the word usually made it in: we had dubbee for butter, purla for pillow, cookah for cookie. There was method in their madness all along.

It’s a wondrous thing, how at some deep level, our babies know how to tackle this bewilderingly complex task. Our role is crucial but easy: All we really have to do is talk, sing and listen to them.

Babies at McGill?

Researchers at McGill University are discovering how babies learn to listen and respond to speech. And you and your baby can help! If you have a child between three and 14 months of age and live in the Montreal area, you can take part in the Infant Speech Perception Project. Parents and babies are together all the time.

You’ll go home with several souvenirs of your visit (a diploma and a baby T-shirt) and the satisfaction of having helped build the scientific understanding of early child development.

For more information, please contact:
Dr. Linda Polka
School of Communication Sciences & Disorders
McGill University
(514) 398-1210 (English)
(514) 398-1659 (Francais)
Web site: medicine.mcgill.ca/infantspeechlab

Originally published in Today's Parent, October 2003