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.