What this means for learners
Armenian and Rundi share 18 sounds — roughly 49% of Rundi's inventory overlaps with Armenian. Shared sounds are ones a speaker already knows from their native language and will generally produce and perceive accurately without explicit training.
The 11 sounds found only in Rundi represent the greatest pronunciation challenge for Armenian 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, Armenian has 19 sounds not used in Rundi. Native Rundi speakers learning Armenian 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.