New babies eat, sleep, cry, poop — and listen. But their eavesdropping begins 

before birth and may include language lessons, says a new study led by 

Christine Moon, a psychologist at Pacific Lutheran University in Tacoma, Wash. 

According to Moon, such early learning may help babies quickly understand their parents.

Scientists have known that about 10 weeks before birth, a fetus can hear sounds 

outside the womb. Until now, evidence suggested that prenatal learning was 

restricted to the melody, rhythm and loudness of voices. But Moon and her 

coworkers found evidence that fetuses may also be starting to learn language 

itself. They tested whether newborns could detect differences in vowel sounds. 

Her team reports that newborns responded one way when they heard sounds like 

those from their parents’ language. And the newborns responded another way 

when they heard sounds like those from a foreign language.

Moon’s team studied 80 healthy newborns ranging from 7 to 75 hours old, half in U.S. hospitals and half in Swedish hospitals. Each baby had a pair of headphones 

nearby. When a baby sucked on a pacifier, the action triggered an attached 

computer to send sounds through the headphones. The babies listened to 17 

sounds similar to the long e in English, heard in the word fee, for example. 

They also listened to 17 sounds similar to a Swedish vowel that sounds like yeh. 

The results showed that American babies were more likely to continue sucking on their pacifiers when they heard Swedish vowels than when they heard English 

vowel sounds and Swedish babies were more likely to continue sucking if they 

heard English vowels. Learning so quickly after birth was unlikely, the researchers concluded, so the ability to monitor the vowels could be attributed only to 

prenatal learning.