Age Differences in the Pronunciation of Foreign Sounds

The hypothesis that the years up to the age of puberty constitute a critical period for language acquisition was tested. Two kinds of data are presented which suggest that younger children are not better than older children and adults in learning a foreign language. In a laboratory study, it was found that the ability to imitate foreign words under controlled input conditions increased linearly with age. In a study of naturalistic second language acquisition, it was found that the older subjects had an initial advantage in pronunciation, and that age differences in pronunciation ability disappeared by 4-5 months after starting to learn the second language. By 10-11 months after starting to speak the second language, the younger children excelled in pronouncing some sounds, though there was still no overall age difference. These results are impossible to reconcile with the predictions of the critical period hypothesis for language acquisition.