What this means for learners
Sirionó and Balinese share 18 sounds — roughly 60% of Balinese's inventory overlaps with Sirionó. Shared sounds are ones a speaker already knows from their native language and will generally produce and perceive accurately without explicit training.
The 6 sounds found only in Balinese represent the greatest pronunciation challenge for Sirionó 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, Sirionó has 12 sounds not used in Balinese. Native Balinese speakers learning Sirionó 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.