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Professor Usha Goswami is among researchers from the University of Cambridge and Trinity College Dublin, Ireland, who jointly investigated babies’ ability to process phonetic information during their first year for their findings published in the ‘Nature Communications’ journal.
They concluded that parents should speak to their babies using sing-song speech, like nursery rhymes, as soon as possible because babies learn languages from rhythmic information, not phonetic information, in their first months.
“Our research shows that the individual sounds of speech are not processed reliably until around seven months, even though most infants can recognise familiar words like ‘bottle’ by this point,” said Goswami.
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Phonetic information, the smallest sound elements of speech, typically represented by the alphabet, has been considered by many linguists the foundation of language.
Infants are thought to learn these small sound elements and add them together to make words.
However, the new study suggests that phonetic information is learnt too late and slowly for this to be the case. Instead, rhythmic speech helps babies learn language by emphasising the boundaries of individual words and is effective even in the first months of life.
The researchers recorded patterns of electrical brain activity in 50 infants at four, seven and eleven months old as they watched a video of a primary school teacher singing 18 nursery rhymes to an infant. Low frequency bands of brainwaves were fed through a special algorithm, which produced a ‘read out’ of the phonological information that was being encoded.
The researchers found that phonetic encoding in babies emerged gradually over the first year of life, beginning with labial sounds (eg d for “daddy”) and nasal sounds (eg m for “mummy”), with the “read out” progressively looking more like that of adults.
First author, Professor Giovanni Di Liberto, a cognitive and computer scientist at Trinity College Dublin and a researcher at the ADAPT Centre, said: “This is the first evidence we have of how brain activity relates to phonetic information changes over time in response to continuous speech.” Previously, studies have relied on comparing the responses to nonsense syllables, like “bif” and “bof” instead. The current study forms part of the BabyRhythm project led by Goswami, which is investigating how language is learnt and how this is related to dyslexia and developmental language disorder.
Goswami believes that it is rhythmic information – the stress or emphasis on different syllables of words and the rise and fall of tone – that is the key to language learning.
“We believe that speech rhythm information is the hidden glue underpinning the development of a well-functioning language system,” said Goswami.
Infants can use rhythmic information like a scaffold or skeleton to add phonetic information. For example, they might learn that the rhythm pattern of English words is typically strong-weak, as in “daddy” or ‘mummy’, with the stress on the first syllable.
They can use this rhythm pattern to guess where a word ends and another begins when listening to natural speech.
“Parents should talk and sing to their babies as much as possible or use infant directed speech like nursery rhymes because it will make a difference to language outcome,” added Goswami.
She explained that rhythm is a universal aspect of every language all over the world: “In all language that babies are exposed to there is a strong beat structure with a strong syllable twice a second. We’re biologically programmed to emphasise this when speaking to babies.” The academic says there is a long history of trying to explain dyslexia and developmental language disorder in terms of phonetic problems but that the evidence doesn’t add up. She believes that individual differences in children’s language originate with rhythm.
The research was funded by the European Research Council under the European Union’s Horizon 2020 research and innovation programme and by Science Foundation Ireland.