What this means for learners
JAPRERIA and Ket share 7 sounds — roughly 22% of Ket's inventory overlaps with JAPRERIA. Shared sounds are ones a speaker already knows from their native language and will generally produce and perceive accurately without explicit training.
The 25 sounds found only in Ket represent the greatest pronunciation challenge for JAPRERIA 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, JAPRERIA has 17 sounds not used in Ket. Native Ket speakers learning JAPRERIA 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.