The boundary-induced modulation of obstruents and tones in Thai

Limited studies have suggested that tones can be strengthened in domain-initial positions, suggesting that domain-initial strengthening (DIS) effects in a tone language extend beyond the first segment of a prosodic domain. However, these studies have yielded unclear results. This study investigated whether DIS causes boundary-induced changes in tones. This study analyzed the maximum fundamental frequency (f0) of the falling, mid, and low tones in Thai along with acoustic measures of consonants, including the Voice Onset Times (VOTs) of /b/, /p/, and /pʰ/, frication duration of /f/, and consonant-induced f0 perturbation effects associated with these four consonants in domain-initial and domain-medial positions. Some evidence of DIS effects on tones was found, suggesting that DIS effects in a tone language can extend to tone production realized with the vowel that is beyond the first segment. Additionally, the VOTs of /b/, /p/, and /pʰ/ were more negative, unchanged, and longer, respectively, the frication of /f/ was longer, and f0 following /pʰ/ was raised in a domain-initial position compared to a domain-medial position. The findings contribute to the current understanding of the prosody-phonetics interface, particularly with respect to the relationship between DIS and the realization of tones.