From small tribes in the remote Pacific islands to the teeming cities of China, humans share the common language of baby talk – but new research has discovered that Wellington, New Zealand, is the global capital of cooing.
An international study, published in Nature Human Behaviour, collected 1615 recordings of 410 people from 21 societies speaking and singing to an adult and then a baby in more than a dozen languages.
The researchers analysed the shift in tones using audio equipment and with the help of more than 50,000 people from 187 countries, who listened to the recordings and guessed if the person was speaking to an infant or an adult.
Participants listened to vocalisations drawn at random from the group of recordings and then viewed the prompt: “Someone is speaking or singing. Who do you think they are singing or speaking to?” They could respond with either “adult” or “baby”.
The study found participants’ ability to tell when someone was speaking to a baby was higher than chance, even when the recordings were from a completely different linguistic family.
However, baby talk in some societies was more easily recognisable than in others. People from Wellington, New Zealand, cooed at a particularly high register, making their baby talk the easiest to distinguish from adult-directed speech.
Prof Quentin Atkinson, a University of Auckland psychologist and one of 43 co-authors of the study, said the project was designed to investigate whether patterns or shifts in the way people speak to infants were present only in western cultures or if they were universal – and if so, do the patterns shift in the same way?
“The [western] assumption that because we speak differently to kids, everyone will, needed testing,” he said.
The study’s findings suggested that people do indeed alter their voices when they are singing or speaking to infants in a way that is consistent across cultures, and that this is a common, evolved function in humans – and one that other humans can recognise.
Despite variability in language, music, and infant-care practices worldwide, when people speak or sing to infants, they modify the acoustic features of their vocalisations in similar and mutually intelligible ways across cultures, the study found.
“Even people in the most distantly related cultures, people from entirely different language families … are able to differentiate between adult and infant-directed songs [and speech],” Atkinson said.
This supported the researchers’ hypothesis that changing your pitch to speak to an infant is a functional tool, similar to the vocal signals many non-human species use to indicate friendliness or alarm and aggression.
Adults adopted more intense and contrasting speech – for example higher pitch and longer pauses – when speaking to an infant, which is more attention grabbing and better to distract an unsettled baby, or facilitates language learning; while songs directed at babies became more subdued and soothing.
The study aimed to gather recordings from diverse societies with varying degrees of isolation from global media, including four small-scale societies that lack access to television, radio or the internet. That was important for ensuring the patterns had not been influenced by other cultures, Atkinson said.
Atkinson could not pinpoint why Wellington residents speak baby talk more than most, and mused that “maybe Wellingtonians just go particularly gaga over babies?”
At the other end of the baby-talk spectrum to Wellingtonians – whose recordings were done by co-authors Alia Martin and Mary Beth Neff at the VUW Infant Cognition Lab – were Tannese Ni-Vanuatu people, from Vanuatu, who had a smaller shift in pitch.
Atkinson, who has spent time with the Tannese Ni-Vanuatu as a researcher, theorised that their more hands-off style of parenting could be linked to smaller “instructive” shifts in intonation.
“Interestingly, there is other work to suggest that … they don’t go out of their way in terms of active teaching, it’s more passive.”
The findings did not mean that infant-directed speech or song sounded the same across cultures, but rather that the shifts in tone were common or regular enough to be recognisable.
The study is a tool towards understanding language development, Atkinson said.
“[The fact that] all over the world people speak in a certain way to infants could be really important – perhaps the way we are talking to them is crucial to learning language.”