Babies are born with their mother's accent
Chris - Scientists at the University of Wurzburg in Germany have teamed up with their colleagues in Leipzig and also in Paris and they found that the cries that young newborn babies emit actually mirror their mother's accents. And to tell us how they discovered that, we are joined now by Kathleen Wermke who is the head of the Centre for Pre-speech Development and Development Disorders and she's at the University Hospital of Wurzburg. Hello, Kathleen.
Kathleen - Hello!
Chris - Welcome to the Naked Scientists.
Kathleen - Thank you.
Chris - What's this study actually show?
Kathleen - The study actually showed an extremely early impact of the surrounding language, of native language, a foetus was exposed to in the womb. This is, of course, new because we knew since many researchers and investigators that during the last year, that infants are sensitive to prosodic features of the native language long before they are born and that they memorize those patterns as a newborn. But it was not known that they are capable so early also, not only to memorize, but also to reproduce those patterns in their own cries.
Chris - How did you do the study?
Kathleen - We recorded the cries of the newborns in Paris and in Berlin in Germany, and then we came back to our laboratory acoustic lab, and we analysed the frequency, spectrogram and the melody contours of the cries, normalized cry time - because not every cry has the same duration - and then we looked for what time point the pitch maximum, the melody maximum was reached. Was that more at the beginning or more at the end of a cry? So we compared between the groups of German and French infants according to their melody contour, having either rising or falling contour.
Chris - Shall we have a listen to some of them?
Kathleen - Okay.
Chris - Well, you sent us some of the recordings you made. So first of all, I'll play the rising cry.
Newborn's Rising Cry
Chris - And here's a falling cry.
Newborn's Falling Cry
Chris - So that's basically one that goes down at the end rather than going up as it goes along. How does that mirror the native language spoken by the mothers of those babies?
Kathleen - It mirrors it because French intonation is characterized by a pitch rise towards the end of several kinds of prosodic units, words or phrases; whereas German, typically, exhibits a falling melody contour.
Chris - And so, why do you think that the babies, when they've got a lot going on in their lives when they're newborns, why should they prioritize being able to mimic mum in this way? Why does this give them benefit?
Kathleen - We think that this observed behaviour is just simply a reflection of the special aptitude human infants have to acquire language. They're hard-wired to acquire language and we know that they have a special sensitivity from melodies and rhythms already being a foetus and then also being born. So we think this is just showing how early language development starts in human infants based on their brain mechanisms and genetic programs, really to acquire language.
Chris - Is this language that they're acquiring in utero? So while they're inside mum and towards the end of pregnancy, they're listening to the sounds and vibrations from her voice being transmitted to them while they're inside and that's where they learn to mimic before they've even been born?
Kathleen - Yeah. That's what we guessed because they are able to listen for three months at least being in the womb and they had only one or two days after delivery. But, of course, we're not sure. Maybe these one or two days after delivery were enough to learn the specific intonation patterns of their surrounding language. We are not sure but we guess that most important are the three months prenatally.
Chris - And in animals?
Kathleen - In animals, it is well known that they have already a lot of prenatal auditive learning. But I'm not sure if anybody checked already the postnatal - the very, very early postnatal impacts of those prenatal learning processes but I'm sure it should be observable in animals too.
Chris - One of the things you say in your paper is that if the baby sounds like mum, she's more likely to bond with it. That seems reasonable.
Kathleen - Probably, yeah. Of course, we don't know but according to the theoretical implication of this study and other studies, it might be that this really fosters bonding between the newborn and the mother, but it seems to be rather unintentional - being just a reflection of the capabilities this human infant has from his genetic programmes and behaviour mechanisms.
Chris - We must leave it there. Thank you very much, Kathleen. That was Kathleen Wermke who's at the University of Wurzburg. She was explaining how babies perceive the general tone of their native language and mimic it even before they're born.