Only in ACOMA 38
What this means for learners
ACOMA and Yao share 13 sounds — roughly 25% of Yao's inventory overlaps with ACOMA. Shared sounds are ones a speaker already knows from their native language and will generally produce and perceive accurately without explicit training.
The 36 sounds found only in Yao represent the greatest pronunciation challenge for ACOMA 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, ACOMA has 38 sounds not used in Yao. Native Yao speakers learning ACOMA 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.