What this means for learners
Arabela and Nasioi share 14 sounds — roughly 48% of Nasioi's inventory overlaps with Arabela. 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 Arabela 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, Arabela has 15 sounds not used in Nasioi. Native Nasioi speakers learning Arabela 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.