Examining the relationship between speech rhythm, fluency measures and comprehensibility ratings in L2 English speech

Abstract This study investigates the relationship between speech rhythm, utterance fluency, and native listeners’ perceptions of comprehensibility and fluency in second language (L2) English. Eighty-two advanced Spanish–Catalan bilingual learners of English completed a spontaneous speaking task, from which temporal rhythm measures (including durational variability metrics and vowel reduction measures) and fluency measures (speed, breakdown, and repair) were extracted. Speech samples were rated for comprehensibility and fluency by L1 English listeners. Correlational and regression analyses revealed that while rhythm and fluency measures did not consistently relate to one another, both independently contributed to listeners’ ratings. In addition, vowel reduction ratios were stronger predictors of ratings than traditional durational variability metrics. These findings suggest that rhythm and fluency constitute partially independent constructs that both shape global speaking proficiency perceptions. Pedagogically, the results highlight rhythm as a promising instructional target for enhancing learners’ fluency and comprehensibility.