Abstract The Ohio State UniversityThe ancient rhyme dictionary Qieyun is the foundation for the study of the history of the Chinese language. Naturally,it has been the subject of intensive analyses by numerous phonologists, but its “sound system"(in a strict sense of the term) has yet to be found, and problems like the so called “initial doublets" have remained a mystery. The present paper tries to determine the vowel phonemes of the sound system of the book by adopting a strict phonemic approach and following closely two fundamental principles, namely, syllable segmentation for that language was (C)(M)V(E),and identical V(E) was the basis for rhyming. It argues that, since the information we can get from the book is strictly phonemical in nature, not phonetic description, “phonetic reconstruction" in the Karlgren style won't be able to reveal the nature of the sound system and regularity of the sound changes that helped forming or altering the system. It disagrees with the claim by many scholars that Qieyun is composite, though it admits the book does include a few “external" elements, dialectal or historical. Instead, it argues that ,logically we have to start with the proposition that Qieyun represents a single sound system, and only after we have succeeded in uncovering that system shall we have a chance to specify what the “external" elements are in the book.
Following this line of thinking, this paper chooses to concentrate on the rhymes with /y/ as ending, namely, those that were assigned to the Zhi She and the Xie She of the Dengyun tables, because their number is bigger than other types of rhymes and their distribution in the Dengyun tables is more complex. The conclusion is a system of seven vowel phonemes, and all the rhymes with /y/ as ending are thereby uniquely represented. Thereupon, problems such as the “initial doublets" and the “double rhymes" are explained as the result of sound changes, the former before and the latter after the time of Qieyun. A set of diachronic rules are thus given to explain the development of “Standard Chinese" from the time slightly before the Qieyun to the time of the Zhongyuan Yinyun.