Aʻoonirobi has a small inventory of consonants (13) but a large number of vowels (16) and, because of the Aʻoonirob's unique vocal physiology, there are no voiceless consonants (besides arguably /ʔ/) and no rounded vowels.

Consonants

1. /v/ is realized as [β] before any trill

2. /ŋ/ becomes palatal [ɲ] when following any nasal vowel

3. /n/ becomes velarized as [nˠ] following a nasal vowel

Vowels

There are 4 'cardinal' vowels /i, ɯ, ɛ, ʌ/ and there is a modal/nasal as well as a short/long distinction for each vowel for a total of 16 vowels.

1. lowers to [æ̃] / [æ̃ː] when adjacent any nasal consonant

2. lowers and centralizes to [ɐ̃] / [ɐ̃ː] adjacent any nasal consonant

Phonotactics

All syllables have the nucleus of any vowel (V), there can optionally be an onset of:
(1) any consonant (C) or
(2) any bilabial or labio-dental followed by a non-bilabial trill (Ŕ)
and finally those can be followed optionally by a coda of any consonant except /j/.

Thus: (C⊻BŔ)V(C*)

Additionally a syllable with a onset of a glottal stop cannot be preceded by a syllable with a coda consisting of a glottal stop. Therefore, (C⊻BŔ)Vʕ.ʕV(C*) is not permitted.

Harmony

No two syllables with differing vowels of the same height can appear consecutively.

So, [i] → [i,ɛ,ʌ], [ɯ] → [ɯ,ʌ,ɛ], [ɛ] → [ɛ,i,ɯ], and [ʌ] → [ʌ,i,ɯ].

Nasal vowel harmony is forward propagating from the root morpheme. So, CVCṼ-CVCV → CVCṼ-CṼCṼ.

However, it is blocked by glottal stops [ʔ] and certain suffixes. So, [tivɛ̃-nɛnɯ] → [tivɛ̃-nɛ̃nɯ̃] but [tivɛ̃ʔ-nɛnɯ] would stay the same.