What this means for learners
Ukrainian and Slovene share 19 sounds — roughly 46% of Slovene's inventory overlaps with Ukrainian. Shared sounds are ones a speaker already knows from their native language and will generally produce and perceive accurately without explicit training.
The 18 sounds found only in Slovene represent the greatest pronunciation challenge for Ukrainian 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, Ukrainian has 22 sounds not used in Slovene. Native Slovene speakers learning Ukrainian 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.