Only in Romanian 29
What this means for learners
Romanian and Bulgarian share 22 sounds — roughly 43% of Bulgarian's inventory overlaps with Romanian. Shared sounds are ones a speaker already knows from their native language and will generally produce and perceive accurately without explicit training.
The 27 sounds found only in Bulgarian represent the greatest pronunciation challenge for Romanian 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, Romanian has 29 sounds not used in Bulgarian. Native Bulgarian speakers learning Romanian 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.