What this means for learners
Russian and Romanian share 25 sounds — roughly 49% of Romanian's inventory overlaps with Russian. Shared sounds are ones a speaker already knows from their native language and will generally produce and perceive accurately without explicit training.
The 26 sounds found only in Romanian represent the greatest pronunciation challenge for Russian 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, Russian has 17 sounds not used in Romanian. Native Romanian speakers learning Russian 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.