In Standard Chinese, Tone 3 (the dipping tone) becomes Tone 2 (rising tone) when followed by another Tone 3. Previous studies have noted that this sandhi process may be incomplete, in the sense that the assimilated Tone 3 is still distinct from a true Tone 2. While Mandarin Tone 3 sandhi is widely studied using carefully controlled laboratory speech (Xu, 1997) and more formal registers of Beijing Mandarin (Yuan & Y. Chen, 2014), less is known about its realization in spontaneous speech, and about the effect of contextual factors on tonal realization. The present study investigates the pitch contours of two-character words with T2-T3 and T3-T3 tone patterns in spontaneous Taiwan Mandarin conversations. Our analysis makes use of the Generative Additive Mixed Model (GAMM, Wood, 2017) to examine fundamental frequency (F0) contours as a function of normalized time. We consider various factors known to influence pitch contours, including gender, duration, word position, bigram probability, neighboring tones, speaker, and also novel predictors, word and word sense (Chuang et al., 2025). Our analyses revealed that in spontaneous Taiwan Mandarin, T3-T3 words become indistinguishable from T2-T3 words, indicating complete sandhi, once the strong effect of word (or word sense) is taken into account.

翻译：在标准汉语中，当第三声（上声）后接另一个第三声时，会变为第二声（阳平）。先前研究指出，这一变调过程可能是不完全的，即被同化的第三声仍与真正的第二声存在区别。尽管已有大量研究利用严格控制的实验室语音（Xu, 1997）及更正式的北京话语体（Yuan & Y. Chen, 2014）对普通话第三声变调进行了探讨，但对其在自发语音中的实现情况，以及语境因素对声调实现的影响，人们知之甚少。本研究考察了台湾国语自发对话中具有T2-T3和T3-T3声调模式的双字词的音高曲线。我们的分析采用生成可加混合模型（GAMM, Wood, 2017），将基频（F0）曲线作为归一化时间的函数进行检验。我们考虑了多种已知会影响音高曲线的因素，包括性别、时长、词位置、二元组概率、相邻声调、说话者，以及新的预测因子——词项与词义（Chuang et al., 2025）。我们的分析表明，在台湾国语自发语音中，一旦考虑到词项（或词义）的强烈效应，T3-T3词与T2-T3词变得无法区分，这表明了完全的变调。