What this means for learners
Atayal and Aleut share 20 sounds — roughly 56% of Aleut's inventory overlaps with Atayal. Shared sounds are ones a speaker already knows from their native language and will generally produce and perceive accurately without explicit training.
The 16 sounds found only in Aleut represent the greatest pronunciation challenge for Atayal 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, Atayal has 7 sounds not used in Aleut. Native Aleut speakers learning Atayal 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.