What this means for learners
Cham and Garo share 16 sounds — roughly 46% of Garo's inventory overlaps with Cham. Shared sounds are ones a speaker already knows from their native language and will generally produce and perceive accurately without explicit training.
The 10 sounds found only in Garo represent the greatest pronunciation challenge for Cham 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, Cham has 19 sounds not used in Garo. Native Garo speakers learning Cham 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.