What's more, the more frequently the mother spoke a particular word, the more likely a baby was to know that word at the end of the study. That means that they automatically keep track of how often a pair of sounds occur together in a sentence. In new work published last month in the journal Developmental Psychology , Saffran showed that most babies have perfect pitch, while adults don't. That means that babies can tell the pitch of a tone without hearing any other sound. With the exception of a few musicians, most adults have lost that ability, instead relying on the relative pitch of two sounds that occur together.
Perfect pitch allows babies to extract meaning from the pitch of different sounds they hear.
Such skills are particularly important for babies who learn tonal languages as their first language. In tonal languages, which constitute one-third of the world's languages, including Cantonese, Thai, and Vietnamese, a word has a different meaning depending on the pitch with which it is spoken, Saffran says. In fact, babies use a variety of strategies, focusing on the most meaningful cues they receive, says Rebecca Gomez, PhD, an assistant professor of psychology at Johns Hopkins University in Baltimore. Besides just learning associations between words that occur adjacent to each other in a spoken sentence, they also learn words that are more widely separated. Gomez used an artificial language to test this ability.