What this means for learners
Kunjen and Cham share 17 sounds — roughly 49% of Cham's inventory overlaps with Kunjen. Shared sounds are ones a speaker already knows from their native language and will generally produce and perceive accurately without explicit training.
The 18 sounds found only in Cham represent the greatest pronunciation challenge for Kunjen 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, Kunjen has 11 sounds not used in Cham. Native Cham speakers learning Kunjen 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.