The special tone of voice, which adults use to talk to babies might be an important part of infant's language learning ability. Researchers suspect that baby talk, with short sentences, slow pace and sing-song tone, helps infants to start distinguishing words from other sounds. But there is no direct evidence for this. Researchers from the Carnegie Mellon University in Pittsburgh found that the typical intonation of baby talk, with its swooping changes in pitch from word to word, seems to help babies begin to recognize where words begin and end. It's not certain that why this happens but it is likely that a sing-song tone captures babies' attention better than the monotone manner adults use with each other. It is very natural for adults to switch to baby talk when speaking to an infant, and it's probably no coincidence that the speech style has a practical use. To investigate the researchers zeroed in on the effect of infant-directed intonation by making 40 infants, of 6.5 to 7.5 months of age, listen to a set of nonsense sentences, spoken either in baby-talk or adult-like tones. After the babies were familiarized with the sentences, the researchers tested whether speech intonation made a difference in the infants' ability to distinguish individual words. They first drew the babies' attention to a flashing light, and then played the sound of either a whole word or a partial word repeatedly until the baby looked away. If an infant gazed longer when a whole word was played versus a partial word, it was taken as a sign that they recognized the word as something distinct. It was found that babies who heard the sentences in baby-talk tones listened longer when a whole word was played than when a partial word was played. In contrast, infants who heard the sentences in adult intonations showed no such preference for whole words. The two sets of sentences the babies heard differed only in tone, that is, the infant-directed sentences carried none of the other features of baby talk, such as short sentences and long pauses after words. This suggests that the sing-song quality of baby talk itself aids in language learning.
Infancy,
April 2005