Lost in Revision: The Disappearance of ㅿ (반치음, panch'iŭm) and ㆁ (옛이응, yesiŭng) in Tusi ŏnhae (두시언해, 杜詩諺解)

This study explores the linguistic changes of two now-obsolete Korean letters, ㅿ(반치음, panch’iŭm) and ㆁ (옛이응, yesiŭng), through a comparative analysis of the early (1481) and revised (1632) editions of the Tusi ŏnhae (두시언해), a Korean translation and annotation of Du Fu’s Tang Dynasty poetry. Drawing on a combination of digitized texts and scanned volumes, the research uses digital tools and manual isolation to systematically track and compare the occurrences and transformations of ㅿand ㆁover the 150-year interval between editions, uncovering significant phonological and orthographic shifts. The study reveals that ㅿ was largely replaced by ㅇ, likely indicating the decline of the voiced alveolar fricative [z] sound. In some cases, ㅿ was replaced by ㅅor omitted entirely, suggesting a more subtle shift than previously recognized. Similarly, ㆁ, representing the velar nasal [ŋ], was replaced by ㅇ, marking its disappearance from both the final and initial position in Korean syllables and the shift of its phonological value to ㅇ. This research builds on previous studies that characterized the orthographic changes between the two editions of Tusi ŏnhae as mechanical and systematic, providing a refined analysis of the disappearance of the letters ㅿ and ㆁ. Through quantitative analysis, this study presents new data on the distribution and usage of these letters, revealing that their disappearance seems to be influenced by various linguistic factors, such as shifts in orthographic norms, regional dialects, and adaptation of literacy to orality.