Abstract
This study aims to probe the vowel system change and the Yin-/Yang-entering monosyllabic tonal variations in Taiwanese Hokkien. In the first part, we analyze the variations of the vowel system in Taiwanese Hokkien by means of a wordlist investigation into eleven dialects in this language, and bring forth variational rules as accords phonological symmetry and adaptive dispersion theory. Our research tells that there exists asymmetry in the six-vowel system /i, e, a, u, o, ɔ/ by the fact that /o/ and /ɔ/ as two vowel systems are too close to be distinguished from each other. This fact results in an on-going divergence of two prestigious variations. One refers to a six-vowel system that we are having particularly in Tai-nan and Kao-hsiung, and the other refers to a five-vowel system where /o/ and /ɔ/ might merge into one in such areas as Da-niu-lan and Jen-tse. In the second part, we find that different codas consequentiate different realizations of the Yin-entering and Yang-entering monosyllabic tonal variations. With a glottal stop, a monosyllabic Yang-entering tone tends to become a mid-long one in some dialects, while it can also become a mid-short tone as in the case of a Yin-entering one in other dialects; still in other dialects, the two tonal variations happen to coexist. When the coda is [-p], [-t] or [-k], sporadic mergence happens between Yang-entering and Yin-entering tones. To sum up, this current study contributes both to finding two subtypes of the vowel system change in Taiwanese Hokkien, and to clarifying the way in which the Yin-entering and Yang-entering monosyllabic tonal variations are realized as the coda varies dynamically with its lexical diffusion in this language.