Only in Tewa 31
What this means for learners
Tewa and Chasta Costa share 26 sounds — roughly 46% of Chasta Costa's inventory overlaps with Tewa. Shared sounds are ones a speaker already knows from their native language and will generally produce and perceive accurately without explicit training.
The 18 sounds found only in Chasta Costa represent the greatest pronunciation challenge for Tewa 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, Tewa has 31 sounds not used in Chasta Costa. Native Chasta Costa speakers learning Tewa 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.