We’re excited to share that researchers, students, and collaborators from ChulaSEAL (Center of Excellence in Southeast Asian Linguistics, Chulalongkorn University) took part in TAI 2025 (Tone and Intonation), held from May 16–18, 2025 in Herrsching am Ammersee, Germany and hosted by the Institute for Phonetics and Speech Processing at LMU Munich.
ChulaSEAL members presented three studies, all focusing on tone and register systems in Southeast Asian languages.
Going Beyond Average Contours in the Study of Tone Variation and Change: A Case Study from Thai Tone 4
Teerawee Sukanchanon (MA student) and Francesco Burroni (Collaborator)
Teerawee and Francesco presented a talk exploring how tone variation in Bangkok Thai (specifically Tone 4, the High tone) can be studied using advanced acoustic analysis. They used techniques like functional principal component analysis (FPCA) and dynamic time-warping hierarchical clustering to go beyond average pitch contours and reveal subtle patterns of change. Their findings show that while younger speakers tend to use a particular variant more often, the overall distribution of tone variants hasn’t drastically changed across generations. They also found that the length of the pitch trajectory plays an important role in tonal variation—something often overlooked in previous studies.
Phonologizing Pitch in Phnom Penh Khmer
Sothornin Mam (PhD student), Pittayawat Pittayaporn (Researcher), and Sireemas Maspong (Collaborator)
This poster examined how pitch differences in Phnom Penh Khmer (PPK) have developed into meaningful, contrastive features. The team focused on how a historical sound change (r > h) led to a new high vs. low pitch contrast—a distinction not found in Standard Khmer. Interestingly, this pitch difference isn’t limited to words with r > h onsets—it also appears in disyllabic words with voiced second syllables. This suggests that Phnom Penh Khmer is in the process of phonologizing pitch, turning it into a core part of the language’s sound system.
Vowel Mergers and Register Change in Chanthaburi Khmer
Pittayawat Pittayaporn (Researcher), Sireemas Maspong (Collaborator), and Sothornin Mam (PhD student)
In another poster, the team looked at how vowel and voice quality interact in Chanthaburi Khmer’s complex register system. They explored how certain vowel contrasts (i:-u: and e:-o:) are maintained through either vowel quality or voice quality, but not both. This suggests that as vowels merge, speakers rely more on other cues like voice quality to preserve distinctions. The study supports Hyman’s model of transphonologization, showing how features like register can emerge, disappear, and re-emerge over time. It also highlights that registrogenesis—the development of register systems—might be more complex and nonlinear than previously thought.
