What this means for learners
Sentani and Lingala share 13 sounds — roughly 59% of Lingala's inventory overlaps with Sentani. 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 Lingala represent the greatest pronunciation challenge for Sentani 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, Sentani has 4 sounds not used in Lingala. Native Lingala speakers learning Sentani 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.