What this means for learners
Quechua and Kunjen share 18 sounds — roughly 49% of Kunjen's inventory overlaps with Quechua. Shared sounds are ones a speaker already knows from their native language and will generally produce and perceive accurately without explicit training.
The 10 sounds found only in Kunjen represent the greatest pronunciation challenge for Quechua 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, Quechua has 19 sounds not used in Kunjen. Native Kunjen speakers learning Quechua 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.