“…As is known, there are numerous prosodic factors functioning in turn taking: boundary tones, rhythm, pitch peak, key shift, pause, lengthening etc. (Truckenbrodt, 2015;Féry, 2016;Ludusn & Schuppler, 2022;Xia et al, 2004Xia et al, , 2023Xia, 2013;Xia & Ma, 2016a, 2016b, 2019. The present work focuses on two of them, which are related to the rhythm of speech, because these two variables play crucial roles in turn-taking, and they are well studied in L1 spontaneous speech, which offer a reliable reference to the study of L2 learners' language, for example, Petrone et al (2017) analyzed the three acoustic prosodic features: pauses, phrase-final lengthening and f0 in German speech production and how these cues affect boundary perception.…”