What this means for learners
Waorani and Kota share 20 sounds — roughly 49% of Kota's inventory overlaps with Waorani. Shared sounds are ones a speaker already knows from their native language and will generally produce and perceive accurately without explicit training.
The 21 sounds found only in Kota represent the greatest pronunciation challenge for Waorani 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, Waorani has 12 sounds not used in Kota. Native Kota speakers learning Waorani 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.