Transfer of sounds from L1 to L2 can obviously lead to inappropriate pronunciations, but assumptions about the effects such transfer may have on native listeners are often based on intuition or casual observation. This paper investigates the effects of direct transfer of four Danish vowels into English through a forced-choice word identification experiment in which actual Danish words were presented to native English listeners as if they were attempts at producing English words. The results of the listening experiment are discussed in relation to predictions made on the basis of textbook descriptions and acoustic analyses of the Danish and English vowels. While some predictions were confirmed, at least one was refuted, and in total this study proved to be a useful supplement to the work on L2 perception which has been carried out within the frameworks established by James E. Flege and Catherine Best.