Palantla Chinantec

Palantla Chinantec, also known as "Chinanteco de San Pedro Tlatepuzco", is a major Chinantecan language of Mexico, spoken in San Juan Palantla and a couple dozen neighboring towns in northern Oaxaca. The variety of San Mateo Yetla, known as Valle Nacional Chinantec, has marginal mutual intelligibility.
A grammar and a dictionary have been published.
The language is unusual in having, for some speakers, a three-way contrast between non-nasalized, lightly nasalized, and heavily nasalized vowels.
Phonology.
Vowels.
Close vowels /i u/ typically are articulated as more open [ɪ ʊ] and are realized as more closed when represented by different tones. The close back vowel /ɯ/ tends to be articulated as [ə] when present in vowel clusters following /u/, or when preceding the /j/ consonant, and may also have a higher central sound. The mid back vowel /ɤ/ tends to be articulated as [ɜ] or [ɨ] when preceding a /w/ consonant. The low central vowel /a/ tends to be realized as [ɐ] following /i/ when one of the consonants /t l n/ occurs.
Each vowel can be nasalized as /ĩ ɯ̃ ũ ɛ̃ ɤ̃ õ ã/.
Stress tones may include either high or low /v́ v̀/ tones.