Patricia Kuhl and her team at the University of Washington in Seattle-who invented the system-had already studied the carefully articulated vowel sounds adults use to talk to babies and toddlers. They found that these baby-talk vowels are not just spoken more clearly but are phonetically different to their adult equivalents. People seem to speak in this way whatever their language, so the researchers wondered if baby talk helps children to learn to speak.
But they could not test the idea directly. "You can't do the experiment because you would need to take one group of children and prevent them being exposed to infant-directed speech," says Bart de Boer, a researcher in Kuhl's group.
So de Boer has simulated the experiment by writing a simple computer program that picks out key vowels in English. He chose "o", "oo" and "ee" because the sounds are very distinctive.
De Boer played the computer recordings of 10 mothers saying the words "sock", "shoe" and "sheep" in two different ways. In one set, the mothers were talking to another adult, while in the other they were talking to their babies.
The computer's task was to distinguish between the three vowel sounds. After analysing about 200 infant-directed words, the computer could easily tell the sounds apart. But when it listened to the same number of recordings of the words as spoken to adults, it recognised only "ee" correctly.
De Boer does not claim that his program learns in the same way as a child. But he says that, like the computer, babies probably understand baby talk better than grown-up speech because of its more distinct vowels.
He hopes his program could also help computer language systems recognise different dialects. But Deb Roy, of MIT's Media Lab in Cambridge, Massachusetts, is not so sure. "This is really telling you more about what adults are doing in talking to their infants than telling you how to build a computer system," he says.
Author: Eugenie Samuel
New Scientist issue: 5th January 2002
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