Waiwai language

Waiwai is a Cariban language of northern Brazil, with a couple hundred speakers across the border in southern Guyana and Suriname.
Katawiana, or Parukuto, is a dialect; Karafawyana is unattested and uncontacted but may be the same.

Phonology

Vowels

/o/ can be heard as when following palatal consonants /tʃ, ʃ/.
/a/ can be heard as when preceded by sounds /j, tʃ/, and followed by sounds /w, m, s/.