Only in Balinese 1
What this means for learners
Toba-Batak and Balinese share 23 sounds — roughly 85% of Balinese's inventory overlaps with Toba-Batak. Shared sounds are ones a speaker already knows from their native language and will generally produce and perceive accurately without explicit training.
The 1 sound found only in Balinese represent the greatest pronunciation challenge for Toba-Batak 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, Toba-Batak has 4 sounds not used in Balinese. Native Balinese speakers learning Toba-Batak 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.