Babies Hear You

Greg likes to think he can tell if someone is listening or not, that 10 years in sales has given him a sixth sense in that regard. So when his wife asked him to talk to their day-old son, he did so out of giddiness of being a new father more than anything.

He didn't believe for a minute the baby understood a word he was saying or that the baby would remember his speaking to him. He doubted if the baby even heard him.

Greg's son can hear and even remember something about what he hears. Of course, these abilities are not as well developed as they are in adults.

To hear as well as adults, newborns need for the sounds to be a little louder until they are about six months old. They're more sensitive to sounds that are typical of human speech, and seem to like "motherese" or "baby talk" more than regular adult speech.

Babies can also remember some of what they hear. The extent to which they do may surprise you.

In one study, newborns recognized passages their mothers had read aloud twice a day during the last five weeks of their pregnancy as being somehow more "familiar" than new passages. Another found that three-day old babies could recognize their mother's voice after hearing it for only about 12 hours.

Babies also show an amazing ability to perceive certain technical aspects of human speech. One main difference between the sounds "bah" and "pah," for example, is the length of time it takes the voice to rise to maximum intensity at the beginning of a syllable. It's done quicker with "bah" than with "pah." We're talking about a tiny fraction of a second difference. But one-month-old babies can make this distinction as well as adults can.
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Speech perception is not so inborn that it doesn't benefit from experience, however. Practice makes us better at making certain distinctions. We tend to lose the ability to make distinctions with sounds we don't hear in our language. Japanese babies, for example, can distinguish "rah" and "lah," but they lose that ability because this distinction does not occur in the Japanese language that they hear.

Fortunately, parents don't have to sweat such technical details. Simply hearing language spoken clearly and frequently is enough for normal development. So, your job is pretty simple. Talk to your baby.

This column is written by Robert B. McCall, Ph.D., Co-Director of the University of Pittsburgh Office of Child Development and Professor of Psychology, and is provided as a public service by the Frank and Theresa Caplan Fund for Early Childhood Development and Parenting Education.