In women's speech, /t/ is realized as [tʃ] before front vowels.
Vowels may be oral or nasal, creaky or modal, long or short: e.g. /kɨ̰̃ː/ "to go".
The preceding vowel nasalizes only if the intervening consonant is voiced, or in some words /ʃ/.
The irregular behavior /ʃ/ is apparently due to it deriving from proto-Mixtec from both voiceless velar */x/ and voiced */j/ ("*y").
It is words in which /ʃ/ derives from *j that allow V1 to be nasalized or contrastively modally voiced.