Only in Slovak 29
What this means for learners
Slovak and Rundi share 16 sounds — roughly 36% of Rundi's inventory overlaps with Slovak. Shared sounds are ones a speaker already knows from their native language and will generally produce and perceive accurately without explicit training.
The 13 sounds found only in Rundi represent the greatest pronunciation challenge for Slovak 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, Slovak has 29 sounds not used in Rundi. Native Rundi speakers learning Slovak 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.