What this means for learners
Hawaiian and Nasioi share 14 sounds — roughly 74% of Nasioi's inventory overlaps with Hawaiian. Shared sounds are ones a speaker already knows from their native language and will generally produce and perceive accurately without explicit training.
The 4 sounds found only in Nasioi represent the greatest pronunciation challenge for Hawaiian 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, Hawaiian has 5 sounds not used in Nasioi. Native Nasioi speakers learning Hawaiian 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.