What this means for learners
Rundi and Hiligaynon share 20 sounds — roughly 69% of Hiligaynon's inventory overlaps with Rundi. Shared sounds are ones a speaker already knows from their native language and will generally produce and perceive accurately without explicit training.
The 5 sounds found only in Hiligaynon represent the greatest pronunciation challenge for Rundi 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, Rundi has 9 sounds not used in Hiligaynon. Native Hiligaynon speakers learning Rundi 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.