LOS ANGELES, July 18 (Xinhua) -- A month before they are born, fetuses can distinguish between someone speaking to them in English and Japanese, according to a new study published in the journal NeuroReport.
Using non-invasive sensing technology for the first time for this purpose, a group of researchers from the University of Kansas has shown this in-utero language discrimination.
"We think it is an extremely exciting finding for basic science research on language. We can also see the potential for this finding to apply to other fields," Utako Minai, associate professor of linguistics and the team leader on the study, said in a press release.
By measuring changes in babies' behavior, previous studies have demonstrated that babies a few days old have been shown to be sensitive to the rhythmic differences between languages.
This early discrimination led researchers to wonder whether children's sensitivity to the rhythmic properties of language may emerge before birth.
"Fetuses can hear things, including speech, in the womb. It's muffled, like the adults talking in a 'Peanuts' cartoon, but the rhythm of the language should be preserved and available for the fetus to hear, even though the speech is muffled," said Minai.
Earlier studies used ultrasound and found that the fetuses were sensitive to the changes in speech sounds by measuring changes in fetal heart rate.
But none using the more accurate device called a magnetocardiogram (MCG) available at the Hoglund Brain Imaging Center at KU Medical Center, researchers said.
"It was not clear if the fetuses were sensitive to the differences in language or the differences in speaker, so we wanted to control for that factor by having the speech sounds in the two languages spoken by the same person," Minai said.
In the new study, researchers had a bilingual speaker make two recordings, one in English and the other in Japanese, to be played in succession to the fetus.
By using MCG, researchers examined two dozen American women, averaging roughly eight months pregnant and found the fetal heart rates changed when they heard the unfamiliar, rhythmically distinct language (Japanese) after having heard a passage of English speech, while their heart rates did not change when they were presented with a second passage of English instead of a passage in Japanese, according to the study.
"We have one of two dedicated fetal biomagnetometers in the United States," said researcher Kathleen Gustafson. "It fits over the maternal abdomen and detects tiny magnetic fields that surround electrical currents from the maternal and fetal bodies."
According to the researchers, the biomagnetometer is more sensitive than ultrasound to the beat-to-beat changes in heart rate.
"These results suggest that language development may indeed start in utero. Fetuses are tuning their ears to the language they are going to acquire even before they are born, based on the speech signals available to them in utero. Pre-natal sensitivity to the rhythmic properties of language may provide children with one of the very first building blocks in acquiring language."
