Chelsea Wald and Bob Hirshon
Bob Hirshon - This week for The Naked Scientists we’re featuring babies. I’m going to talk about their extraordinary ability to recognize languages, even before they can talk. But first, the sound of a crying baby is said to be one of the most disturbing in the whole world. But Chelsea has found a scientist who can turn it into beautiful music.
Chelsea Wald - [Baby crying] Don’t you sometimes wish crying babies sounded more like, say, pianos? [morphs into a piano] Well, you have your wish, at least temporarily, thanks to acoustician Kelly Fitz of the Starkey Hearing Research Center. He says morphing sounds together makes for cool sound effects and innovative music.
Kelly Fitz (Starkey Hearing Research Center) - I always wanted to be a composer, and I thought that this way of working with sound was of interest but the tools just really haven’t been strong enough.
Chelsea - His new technique first breaks down two sounds into their component tones, like this. [trumpet sound] Then he adds the components of one sound to the other to make a seamless transformation. [trumpet morphs to crying baby] Oh, so we’re back to the baby again? I guess in the real world there’s no substitute for just changing the diapers. [To hear the sounds featured in this week's Science Update - Listen to the podcast!]
Bob - Thanks, Chelsea. Babies can barely do anything for themselves, but those as young as four months can tell their native language from a foreign tongue, even if they can't hear a word of either. This according to a study led by psychologists Whitney Weikum and Janet Werker of the University of British Columbia in Canada. Werker says past research has shown that babies can discriminate the sound patterns of different languages from a very early age.
Janet Werker - But because speech is so richly multimodal, and because past research has shown that babies pay attention to both the visual and auditory aspects of speech, we asked “Gee, can they use just the visual information alone, and can they use that to help identify speakers of their native language?”
Bob - Her team showed babies silent videos of bilingual adults, speaking alternatively in English and French. Weikum says that babies' attention instinctively perks up when they detect a language switch.
Whitney Weikum (University of British Columbia) - And we found that at four and six months, babies from the home where only English is spoken can tell the difference between the languages. But their ability to tell the difference between the languages declined by eight months of age.
Bob - On the other hand, babies raised in bilingual homes showed no such decline, suggesting that this ability persists only if it's needed just as the ability to discriminate between certain vowel and consonant sounds fades away, if those differences aren't important in one's native language. As for the ability to distinguish between languages by sight, it's not yet clear whether this is merely a phase of normal language development, or the result of an evolutionary advantage for babies who could recognize other members of their community.
Chelsea - Thanks, Bob. Next time, we’ll talk about how scientists are trying to kick the healing process up a notch. Until then, I’m Chelsea Wald…
Bob - …and I’m Bob Hirshon, for AAAS, The Science Society. Back to you, Naked Scientists…