Open and closed mouth, hepi ( 闔闢 ) and xipi ( 翕闢 ) in Dongguk jeongun-style Sino-Korean readings

This paper investigates transcriptions of open and closed mouth in Dongguk jeongun ( 東國正韻 )-style Sino-Korean readings, in an effort to grasp one of the still unsolved problems in Korean phonology: the origin of the phonological framework of Dongguk jeongun. By comparing these readings with Chinese and vernacular Sino-Korean readings, this paper has reached the following conclusions. 1) As a standard sound system, Dongguk jeongun-style readings are characterized by a uniformity in the sense that they permit no exceptions within a rime group, producing a striking difference from vernacular readings. 2) Contrary to expectations, it has been revealed that no sound system (neither Chinese nor vernacular Sino-Korean) can be proposed as a single model for this Korean rime book. One of its uniformity comes from its positive acceptance of open and closed mouth, regardless of origin; whether from Middle Chinese, later Chinese reflected in Gǔjīnyùnhuì jǔyào ( 古今韻會擧要 ), or vernacular Sino-Korean readings. Open and closed mouth has been here found to function as a strong part of the framework to the compilers of Dongguk jeongun. 3) The concept of open and closed, or xīpì ( 翕闢 ), as mentioned in Shin Suk-ju’s preface, can be added to the underlying principles of Dongguk jeongun, along with Seven Sounds ( 七音 ), Clear and Muddy ( 淸濁 ), and Four Tones ( 四聲 ). The term xīpì ( 翕闢 ) is correspondent to hépì ( 闔闢 ), which is mentioned in Haerye ( 訓民正音解例 ), rather than to kāihé ( 開合 ) in Yùnjìng ( 韻鏡 ).