What this means for learners
Dagbani and Nupe share 27 sounds — roughly 71% of Nupe's inventory overlaps with Dagbani. Shared sounds are ones a speaker already knows from their native language and will generally produce and perceive accurately without explicit training.
The 11 sounds found only in Nupe represent the greatest pronunciation challenge for Dagbani 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, Dagbani has 10 sounds not used in Nupe. Native Nupe speakers learning Dagbani 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.