What this means for learners
PO-AI and Cham share 18 sounds — roughly 51% of Cham's inventory overlaps with PO-AI. Shared sounds are ones a speaker already knows from their native language and will generally produce and perceive accurately without explicit training.
The 17 sounds found only in Cham represent the greatest pronunciation challenge for PO-AI 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, PO-AI has 17 sounds not used in Cham. Native Cham speakers learning PO-AI 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.