Measuring phonological complexity in Thai: Adaptation and application of the word complexity measure.

PURPOSE: This study aims to develop a tool for assessing phonological complexity in Thai, based on the Word Complexity Measure. An adapted version, the Word Complexity Measure-Thai, is introduced with the hypothesis that existing Thai clinical wordlists do not represent phonological complexity evenly across parameters. The study also proposes a new preliminary Thai wordlist as a prototype for testing phonological complexity. METHOD: The Word Complexity Measure-Thai was developed and applied to analyse seven Thai wordlists used in speech sound production assessment. The distribution of seven parameters across three domains (word patterns, syllable structures, and sound classes) was examined. A new 50-word prototype list was then constructed to achieve balanced parameter distribution, using the Word Complexity Measure-Thai scoring criteria. RESULT: Findings showed that current Thai wordlists fail to capture phonological complexity comprehensively. Some parameters, such as final consonants, were overrepresented; while consonant clusters and trills were rare. Polysyllabic words were notably lacking. The new list demonstrated balanced representation across all domains. CONCLUSION: The Word Complexity Measure-Thai and its prototype wordlist have the potential to serve as a complementary clinical tool, providing a detailed and developmentally appropriate means to assess Thai children's speech and a linguistically-grounded foundation for future phonological research.