Hainanese has seven phonemic vowels.
| Front | Central | Back | |
|---|---|---|---|
| Close | /i/ | /u/ | |
| Close-mid | /e/ | /o/ | |
| Open-mid | /ɛ/ | /ɔ/ | |
| Open | /a/ |
Hainanese notably has a series of implosive consonants, which it acquired through contact with surrounding languages, probably Hlai.
| Labial | Dental | Alveolo-palatal | Velar | Glottal | ||
|---|---|---|---|---|---|---|
| Plosive | voiceless | /p/ 八/帮 poi/pang |
/t/ 心/洗 tim/toi |
/k/ 公/讲 kóng/kǒng |
(/ʔ/) 安/啊 an/ah | |
| Aspirated | /pʰ/ 婆/朋 pho/phang |
(/kʰ/) 去 khu |
||||
| voiced/implosive | /ɓ/ 肥/笨 bui/bun |
/ɗ/ 汝/茶 du/dei |
(/ɠ/) | |||
| Affricate | /ts/~/tɕ/ 真/食 tsin/tsia |
|||||
| Fricative | voiceless | /f/ 皮/非 fi/fuai |
/s/~/ɕ/ 事/出 sei/sut |
/x/ 去 hu |
/h/ 海/睡 hai/hoi | |
| voiced | /v/ 文/我 vun/va |
/z/~/ʑ/ 日/原 zeh/zuan |
/ɦ/ | |||
| Nasal | /m/ 面/目 min/mak |
/n/ 南/年 nam/nin |
/ŋ/ 五/严 ngou/ngiam |
|||
| Approximant | (/w/) 发/王 wat/wong |
/l/ 蓝/老 lam/lao |
(/j/) 肉/也 yok/ya |
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The phonological system of Hainanese corresponds well with that of Hokkien, but it has had some restructuring. In particular, etymological *anterior plain stops have undergone implosivization (*p > [ɓ], *t > [ɗ], etymological *aspirated stops have spirantized (*pʰ > [f], *tʰ > [h], *cʰ > [ɕ] *kʰ > [x]), and etymological *s have hardened into stops (*s > [t]), and *h > [ɦ]. Additionally, some dialects have [ɡ], and [ʑ] is allophonic with /j/.