What this means for learners
KOIARI and BODO share 12 sounds — roughly 57% of BODO's inventory overlaps with KOIARI. Shared sounds are ones a speaker already knows from their native language and will generally produce and perceive accurately without explicit training.
The 9 sounds found only in BODO represent the greatest pronunciation challenge for KOIARI speakers. The adult brain tends to map unfamiliar sounds onto the closest native equivalent — a process that produces the characteristic "accent" of a second-language speaker. Learning to hear and produce these sounds as distinct requires focused ear training, not just repetition.
Conversely, KOIARI has 4 sounds not used in BODO. Native BODO speakers learning KOIARI will face the mirror-image challenge with these sounds.
Phoneme inventories from PHOIBLE. Data reflects one documented inventory per language; some variation exists across dialects and sources.