Researchers took a look at some especially young infants: 40 boys and girls between seven and 75 hours old were studied in both Tacoma, Wash. and Stockholm, Sweden. The team set up a pretty bizarre and ingenious metric for determining how well the babies recognized the speech: they measured how long the kids sucked on a pacifier wired to a computer. First the researchers split both the Swedish and American babies into two groups. Within each of those groups, they rigged a pacifier to detect when each of the babies sucked, then started to pipe in vowels. Half of the babies in each group got vowels in their native language, while the other half got the foreign one. The babies consistently sucked faster on the pacifier when a foreign language was being played, which, the researchers say, is evidence they're ready for something new by the time they're a few hours old.