What this means for learners
Haida and Hupa share 28 sounds — roughly 56% of Hupa's inventory overlaps with Haida. Shared sounds are ones a speaker already knows from their native language and will generally produce and perceive accurately without explicit training.
The 14 sounds found only in Hupa represent the greatest pronunciation challenge for Haida 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, Haida has 22 sounds not used in Hupa. Native Hupa speakers learning Haida 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.