Prosodically-conditioned fine-tuning of coarticulatory vowel nasalization in English

This study explores the relationship between prosodic strengthening and linguistic contrasts in English by examining temporal realization of nasals (N-duration) in CVN# and #NVC, and their coarticulatory influence on vowels (V-nasalization). Results show that different sources of prosodic strengthening bring about different types of linguistic contrasts. Prominence enhances the consonant׳s [nasality] as reflected in an elongation of N-duration, but it enhances the vowel׳s [orality] (rather than [nasality]) showing coarticulatory resistance to the nasal influence even when the nasal is phonologically focused (e.g., mob-bob; bomb-bob). Boundary strength induces different types of enhancement patterns as a function of prosodic position (initial vs. final). In the domain-initial position, boundary strength reduces the consonant׳s [nasality] as evident in a shortening of N-duration and a reduction of V-nasalization, thus enhancing CV contrast. The opposite is true with the domain-final nasal in which N-duration is lengthened accompanied by greater V-nasalization, showing coarticulatory vulnerability. The systematic coarticulatory variation as a function of prosodic factors indicates that V-nasalization as a coarticulatory process is indeed under speaker control, fine-tuned in a linguistically significant way. In dynamical terms, these results may be seen as coming from differential intergestural coupling relationships that may underlie the difference in V-nasalization in CVN# vs. #NVC. It is proposed that the timing initially determined by such coupling relationships must be fine-tuned by prosodic strengthening in a way that reflects the relationship between dynamical underpinnings of speech timing and linguistic contrasts.