What this means for learners
EFIK and Lingala share 19 sounds — roughly 86% of Lingala's inventory overlaps with EFIK. Shared sounds are ones a speaker already knows from their native language and will generally produce and perceive accurately without explicit training.
The 3 sounds found only in Lingala represent the greatest pronunciation challenge for EFIK 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, EFIK has 1 sound not used in Lingala. Native Lingala speakers learning EFIK 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.