Vowel nasalisation in American English has been the subject of a long discussion as to whether it is a phonological process or whether it should better be analysed as phonetic coarticulation. As a predictable allophonic process, vowel nasalisation also provides a testing ground for theories of lexical representation, since if it turns out that language users store this predictable information in long-term memory, there is no reason to assume any kind of phonological underspecification. In this article, experimental studies on this phenomenon are reviewed with these two questions in mind: is the phenomenon a phonological process at all and is this predictable information, i.e. vowel nasalisation, stored in the mental lexicon. The majority of studies provide evidence supporting the phonological view and underspecified lexical representations.
