[1] Official Uyghur orthographies do not mark vowel length, and also do not distinguish between /ɪ/ (e.g., بىلىم /bɪlɪm/ 'knowledge') and back /ɯ/ (e.g., تىلىم /tɯlɯm/ 'my language'); these two sounds are in complementary distribution,[clarification needed] but phonological analyses claim that they play a role in vowel harmony and are separate phonemes.
[5] The pairs /p, b/, /t, d/, /k, ɡ/, and /q, ʁ/ alternate, with the voiced member devoicing in syllable-final position, except in word-initial syllables.
This devoicing process is usually reflected in the official orthography, but an exception has been recently made for certain Perso-Arabic loans.
Syllable-final /r/, /l/, and /j/ are optionally assimilated to the preceding vowel which is lengthened, in the case of e and u, made lower and less tense; e.g., xelqler [xæːqlæː] ‘the nations’.
This phenomenon occurs most common in colloquial speech, but is often avoided when reciting, reading, or singing.
As a result, Uyghur speakers often hypercorrect by inserting an [r] after a long vowel where there is no phonemic /r/, especially after attaching a vowel-initial suffix (e.g. bina 'building', binarim or binayim 'my building').
Other phonemes occur natively only in limited contexts, i.e. /h/ only in few interjections, /d/, /ɡ/, and /ʁ/ rarely initially, and /z/ only morpheme-final.
[14] Uyghur syllable structure is usually CV or CVC, but CVCC can also occur in some words.
In general, Uyghur phonology tends to simplify phonemic consonant clusters by means of elision and epenthesis.