Iaai is remarkable for its large inventory of unusual phonemes, in particular its consonants, with a rich variety of voiceless nasals and approximants.

/æ æː/ only occurs after the plain labial consonants and the vowel /y yː/, the same environment that produces [œ œː].

[4] Unlike many languages with denti-alveolar stops, Iaai /t̪, d̪/ are released abruptly, and /t̪/ has a very short voice onset time.

The labial approximants are placed in their respective columns following their phonological behaviour (their effects on following vowels), but there is evidence that all members of these series are either labial-palatal or labial-velar.

In many cases, words with voiced and voiceless approximants are morphologically related, such as /liʈ/ "night" and /l̥iʈ/ "black".

There is evidence that non-labialized labial consonants such as /m/ are palatalized /pʲ/, /mʲ/, etc., but this is obscured before front vowels.