What this means for learners
Croatian and Lak share 18 sounds — roughly 26% of Lak's inventory overlaps with Croatian. Shared sounds are ones a speaker already knows from their native language and will generally produce and perceive accurately without explicit training.
The 51 sounds found only in Lak represent the greatest pronunciation challenge for Croatian 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, Croatian has 18 sounds not used in Lak. Native Lak speakers learning Croatian 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.