This study aims to tease apart two proposals regarding the phonetic realization of toneless TBUs: that they are realized with default (often L) tones (Yip 2002; Zhang 2016), or that they stay without phonological tones and surface as interpolated pitch between tonal targets (Pierrehumbert & Beckman 1988; Zhang et al. 2019). The original fieldwork data of toneless moras in Suzhou Chinese (Northern Wu) demonstrated considerable variation in toneless realization, both across- and within-speaker. Assessed by the simulation & classification framework of Shaw and Kawahara (2018), some speakers more frequently used interpolation between tones (e.g., high level between Hs, low rising between L and H), while others realized the toneless mora with a relatively low pitch regardless of the tonal context. In addition, tonal contexts also affected how toneless moras were realized, with more interpolation when the toneless moras were surrounded by two Hs, and more default L insertion when the mora was preceded by L and followed by H. There was no unified way of toneless realization in Suzhou, much like a model of probablistic/variable phonological process would predict (Coetzee & Pater 2011; Coetzee & Kawahara 2013)
