In the so-called “third great debates on Old Chinese phonology” in recent years, there has been heated discussions on “yisheng zhi zhuan一声之转 (sound shift)” mentioned in the Guangya shuzheng, with a particular focus on the legitimacy of Wang Niansun’s theories on Chinese historical phonology. Wang Niansun followed the paradigm set up by Dai Zhen in identifying cognate words. In Dai Zhen’s Fangyan shuzheng as well as Duan Yucai’s Shuowenjiezi zhu, there is a large number of “Zhuanyu转语 (transmitted words)” materials. This paper collects the “Zhuanyu” materials from the three exegetical works above, analyzes contact types of initials, and discusses the different accounts of Old Chinese initials proposed by Dai Zhen, Duan Yucai and Wang Niansun, under the historical context between the reigns of Qianlong and Jiaqing. We find that Qian Daxin’s view of Old Chinese initials was not well received at that time. While Duan Yucai and Wang Niansun both adopted Dai Zhen’s “Shengzhuan theory声转说”, they made adjustments by prioritizing either “zhengzhuan 正转 (positive shifting)” or “bianzhuan 变转 (alternative shifting)”. This paper also compares the different evaluations of textual evidence vis-à-vis phonological theory in the exegetical studies of Dai, Duan and Huang, and analyzes disagreements between contact behaviors of initials and Shengzhuan theories in their “Zhuanyu” materials. Our study clarifies misunderstandings about “yisheng zhi zhuan” and provides insights for reconstructing the academic history of traditional Chinese phonology.