The Layers of Vowel Phonological System and Variation of Sibe Language

In the vowel phonological system of oral Sibe, the appearance of /ɛ/, /oe/ and /y/ is rare and is conditionally constrained by certain partially predictable phonological environments, thus falling between the domains of “phoneme” and “allophone”. This paper attempts to propose two layers in the vowel phonological system, say the frequent and unpredictable vowels, /a/, /ə/, /i/, /o/, /u/, as the “central phonemes”, whereas the /ɛ/, /oe/ and /y/ the “marginal phonemes”. Due to be in the state of sound change in progress, /ɛ/, /oe/ and /y/ show several lexical variants on the synchronic level. This paper will compare and analyze the recent research in 2004 with the previous study in 1982 to illustrate a comprehensive picture of the vowel variation in modern Sibe language.