Babies with bilingual moms process sound differently

You may go gaga over this new study’s results.  

Babies with multilingual mothers process sound differently in their brains and are more sensitive to a wider range of pitches, according to a study published in Frontiers in Human Neuroscience.

“Here we show that exposure to monolingual or a bilingual speech has different effects at birth on ‘neural encoding’ of voice pitch and vowel sounds: that is, how information about these aspects of speech has been initially learned by the fetus,” Natàlia Gorina-Careta, a researcher at the Institute of Neurosciences of the University of Barcelona and the first joint author of the study, said in a press release. 

“At birth, newborns from bilingual mothers appear more sensitive to a wider range of acoustic variation of speech, whereas newborns from monolingual mothers seem to be more selectively tuned to the single language they have been immersed in,” she added.

Researchers studied mothers in Catalonia, Spain, where 12% of the population speak both Catalan and Spanish. 

The study included moms of 131 one- to three-day-old newborns, including two pairs of twins, at Sant Joan de Déu Barcelona Children’s Hospital.

In a questionnaire, 41% of the mothers said they only spoke one language during their pregnancy and the other 59% spoke at least two languages, which also included Arabic, English, Romanian and Portuguese. Of the 41% who spoke just one, 9% spoke Catalan and 91% spoke Spanish. 

The researchers then studied the babies’ brain responses to certain speech sounds by putting electrodes on their foreheads. 

The sounds were “composed of four stages: the vowel /o/, a transition, the vowel /a/ at a steady pitch, and /a/ rising in pitch,” the press release explained. 

“The contrasting vowels /o/ and /a/ belong to the phonetic repertoire of both Spanish and Catalan, which is partly why we chose them,” study co-author Sonia Arenillas Alcón, also a researcher at the University of Barcelona, said in the release. 

“Low-frequency sounds like these vowels are also transmitted through the womb reasonably well, unlike mid- and high-frequency sounds that reach the fetus in a degraded and attenuated manner,” she added. 

Babies whose moms spoke just one language responded more to the /o a/ sound because they were more attuned to the pitch of their mother’s language. Babies with multilingual mothers were more sensitive to all the sounds. 

Researchers said this means that babies with monolingual moms are sensitive to the pitch of language, whereas babies of bilingual moms are sensitive to a bigger range of pitch frequencies, though they didn’t respond more to any one frequency. 

“Our data show that prenatal language exposure modulates the neural encoding of speech sounds as measured at birth. These results emphasize the importance of prenatal language exposure for the encoding of speech sounds at birth, and provide novel insights into its effects,” said study co-author Carles Escera, a professor at University of Barcelona.