Prosodic Structural Effects on Non-Contrastive Coarticulatory Vowel Nasalization in L2 English by Korean Learners

This acoustic study explores how Korean learners produce coarticulatory vowel nasalization in English that varies with prosodic structural factors of focus-induced prominence and boundary. N-duration and A1-P0 (degree of V-nasalization) are measured in consonant-vowel-nasal (CVN) and nasal-vowel-consonant (NVC) words in various prosodic structural conditions (phrase-final vs. phrase-medial; focused vs. unfocused). Korean learners show a systematic fine-tuning of the non-contrastive V-nasalization in second language (L2) English in relation to prosodic structure, although it does not pertain to learning new L2 sound categories (i.e., L2 English nasal consonants are directly mapped onto Korean nasal consonants). The prosodic structurally conditioned phonetic detail in English appears to be accessible in most part to Korean learners and was therefore reflected in their production of L2 English. Their L2 production, however, is also found to be constrained by their first language (L1-Korean) to some extent, resulting in some phonetic effects that deviate from both L1 and L2. The results suggest that the seemingly low-level coarticulatory process is indeed under the speaker's control in L2, which reflects interactions of the specificities of the phonetics-prosody interface in L1 and L2. The results are also discussed in terms of their implications for theories of L2 phonetics.