Iu Mien phonology

Consonants
There are 31 cited consonant phonemes in Iu Mien. A distinguishing feature of Iu Mien consonants is the presence of voiceless nasals and laterals.


 * 1) The standard spelling system for Iu Mien does not represent the stop sounds in a way that corresponds to the IPA symbols, but instead uses e.g. $\langlet\rangle$, $\langled\rangle$, and $\langlend\rangle$ to represent . This may stem from an attempt to model the Iu Mien spelling system on Pinyin (used to represent Mandarin Chinese), where $\langlet\rangle$ and $\langled\rangle$ represent .  The Pinyin influence is also seen in the use of $\langlec\rangle$, $\langlez\rangle$, and $\langlenz\rangle$ to represent the alveolar affricates  and $\langleq\rangle$, $\langlej\rangle$, and $\langlenj\rangle$ for the postalveolar affricates .  Note also that the use of $\langleng\rangle$ to represent the velar nasal  means that it cannot also be used to represent, as would be predicted; instead, $\langlenq\rangle$ is used.
 * 2) According to Aumann and Chengqian, in a certain Chinese dialect, the postalveolar affricates are instead palatal stops (/cʰ/, /c/, /ɟ/).
 * 3) According to Daniel Bruhn, the voiceless nasals are actually sequences  (i.e. a short nasalized /h/ followed by a voiced nasal), while the voiceless lateral is actually a voiceless lateral fricative.
 * 4) Bruhn also observed that younger-generation Iu Mien Americans were more likely to substitute the voiceless nasals and voiceless laterals with /h/ and the alveolo-palatal affricates with their corresponding palato-alveolar variants.

Onset
It appears that all single consonant phonemes except /ʔ/ can occur as the onset.

Coda
Unlike Hmong, which generally prohibits coda consonants, Iu Mien has seven single consonant phonemes that can take the coda position. These consonants are /m/, /n/, /ŋ/, [p̚], [t̚], [k̚], and /ʔ/. Some of the stops can only occur as final consonants when accompanied by certain tones; for example, /ʔ/ only occurs with the tone $\langlec\rangle$ or $\langlev\rangle$.

Vowels
Iu Mien vowels are represented in the Iu Mien United Script using combinations of the six letters, $\langlea\rangle$, $\langlee\rangle$, $\langlei\rangle$, $\langleo\rangle$, $\langleu\rangle$, and $\langler\rangle$.

According to Bruhn, the monophthongs are $\langlei\rangle$, $\langleu\rangle$, $\langlee\rangle$, $\langleo\rangle$, $\langleai\rangle$, $\langleer\rangle$, $\langleae\rangle$, $\langlea\rangle$, $\langleaa\rangle$, and $\langleor\rangle$. The diphthongs are $\langleai\rangle$, $\langleaai\rangle$, $\langleau\rangle$, $\langleaau\rangle$, $\langleei\rangle$, $\langleoi\rangle$, $\langleou\rangle$, $\langleeu\rangle$. Furthermore, additional diphthongs and triphthongs can be formed from the aforementioned vowels through /i/- or /u/-on-gliding (having /i/ or /u/ before the vowel). Such vowels attested by Bruhn include $\langleia\rangle$, $\langleiaa\rangle$, $\langleie\rangle$, $\langleio\rangle$, $\langleiu\rangle$, $\langleior\rangle$, $\langleiai\rangle$, $\langleiaai\rangle$, $\langleiau\rangle$, $\langleiaau\rangle$, $\langleiei\rangle$, $\langleiou\rangle$, $\langleua\rangle$, $\langleuaa\rangle$, $\langleuae\rangle$, $\langleue\rangle$, $\langleui\rangle$, $\langleuo\rangle$, $\langleuai\rangle$, $\langleuaai\rangle$, and $\langleuei\rangle$.

The dialect studied by Bruhn, and described in the above table, has a phoneme that does not have its own spelling, but is represented in various contexts either as $\langlee\rangle$ or $\langleai\rangle$ (which are also used for /e/ and, respectively). In all cases where is spelled $\langlee\rangle$, and nearly all cases where it is spelled $\langleai\rangle$, it does not contrast with /e/ or, respectively, and can be viewed as an allophone of these sounds. The only potential exception appears to be when occurring as a syllable final by itself, where it has an extremely restricted distribution, occurring only after the (alveolo-)palatal consonants. The sound may be a secondary development from  in this context, although Bruhn does not discuss this issue.

Tones
Iu Mien is a tonal language with six observed tonemes.

In the Iu Mien United Script (the language's most common writing system), tones are not marked with diacritics; rather, a word's tone is indicated by a special marker letter at the end of the word. If a word lacks a marker, then it is to be pronounced with a middle tone.