The interplay of segmentals and suprasegmentals in the perception of L2 comprehensibility in Chinese-accented Thai

Comprehensibility refers to the ease of understanding in second language (L2) speech. This paper examines the relative contribution of segmentals and suprasegmentals on perceived L2 comprehensibility. Fifteen Chinese speakers of Thai were asked to produce Thai segmentals and suprasegmentals in a picture description task. Acoustic analyses demonstrated that Chinese-accented Thai speech was distinct from native Thai speech in both segmentals and suprasegmentals. In addition, native Thai raters (n = 30) also evaluated the degree of comprehensibility using a 9-point Likert scale. A stepwise regression analysis revealed the joint predictiveness of segmentals and suprasegmentals on L2 comprehensibility, which collectively accounted for more than 50% of the variance in comprehensibility ratings. Specifically, suprasegmentals (i.e., filled pauses and speech rate) and segmentals (i.e., duration of diphthongs and quality of back monophthongs) were identified as the most robust predictors for comprehensibility in Chinese-accented Thai. The findings offer direct evidence that comprehensibility is intricately linked to several L2 features from the domains of segmentals and suprasegmentals. Therefore, understanding of the nature of L2 comprehensibility in Thai requires considering the interplay between segmentals and suprasegmentals. In light of this, it is proposed that emphasis is required on both segmentals and suprasegmentals in L2 instruction in order to achieve more comprehensible L2 speech.