The purpose of this paper is a description of the phonological system and phonetic details of the central Vientiane dialect of Lao. A syllable is analyzed into three elements. They are the consonant, the rhyme, and the tone. The rhyme has a vowel and a final consonant.
There are twenty consonants; / p, t, c, k, ?, ph, th, kh, b, d, m, n, _??_, _??_, f, s, h, w, y, l / . There are nine vowels; / i, e, ε, _??_, ∂, a, u, o, _??_/, and three dipthongs; / ia, _??_a, ua / . Each vowel has the phonemic contrast between short and long. And there are nine final consonants; / p, t, k, ?, m, n, _??_, w, y/.
The tones are five for native speakers of central Vientiane. The five tones are low rising, high rising, high mid level, low falling and high falling. However, there is a non-phonemic distinctive variation in the low rising tone category.
This dialect also shows an exceptional syllable with no final consonant only when the vowel is / a / in the non-final syllable of the polysyllabic word. It is unstressed and neutral in the tone.