A new study conducted at the University of Washington (UW) in the US suggests that babies can tell the difference between speech sounds in more than one language until they are about eight months of age. The research suggest that babies mentally practise speech until they begin to talk.
The scientists scanned the brains of seven- and 11-month-old babies, and discovered that speech sounds in different languages stimulate the superior temporal gyrus, an auditory brain region associated with language; the Broca’s area, which is associated with speech; the cerebellum, which helps control movement, as well as other areas that are responsible for planning motor movements required for producing speech.
“Most babies babble by seven months, but don’t utter their first words until after their first birthdays,” said lead author Patricia Kuhl, professor of speech and hearing science at UW, in a press release. “Finding activation in motor areas of the brain when infants are simply listening is significant, because it means the baby brain is engaged in trying to talk back right from the start and suggests that seven-month-olds’ brains are already trying to figure out how to make the right movements that will produce words.”
In the study, babies listened to sounds in English and Spanish. All the seven-month-old babies showed the same pattern of brain activation, which demonstrated that at such an early age babies respond to all speech sounds, regardless of which belong to their native tongue.
When older babies listened to sounds both in English and Spanish, their response was different. When exposed to non-native speech sounds their brain activity increased, showing that they had a harder time trying to figure out which movements they needed to make to produce that unfamiliar sound. This also suggest that about eight months of age infants start to focus in just the sounds they hear all the time.
The researchers suggest that babies practise all the mouth and tongue movements they will need to speak before they utter their first-word. All this planning also helps them be more aware of their native tongue.
“Hearing us talk exercises the action areas of infant’s brains, going beyond what we thought happens when we talk to them,” Kuhl said in a release. “Infants’ brains are preparing them to act on the world by practising how to speak before they actually say a word.”
The study was published in the journal Proceedings of the National Academy of Sciences.