This paper provides a comprehensive review of the measures of dialogue fluency, with a focus on within-turn fluency and between-turn fluency. First, within-turn fluency includes three dimensions: speed, breakdown (pauses and prolongations), and repair, while between-turn fluency focuses on turn pause and alignment. By reviewing previous studies, this research summarizes measures for within-turn fluency, particularly the application of composite measures (e.g., frequency of filled pauses, combining pause duration) in fluency studies. The findings reveal that speed, including both pure speed measures like articulation rate and combined measures such as speech rate encompassing both speed and pause, is the most commonly used measure in within-turn fluency studies. Additionally, research on between-turn fluency has been gradually increasing in recent years. Common between-turn fluency measures, as well as other potential measures, are summarized in this paper. Overall, this paper provides a theoretical framework and practical guidance for the selection of measures in future empirical studies and to enhance the systematicity of fluency assessment frameworks in future second language assessments.
