Only in Spanish 25
What this means for learners
Spanish and Croatian share 20 sounds — roughly 44% of Croatian's inventory overlaps with Spanish. Shared sounds are ones a speaker already knows from their native language and will generally produce and perceive accurately without explicit training.
The 16 sounds found only in Croatian represent the greatest pronunciation challenge for Spanish 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, Spanish has 25 sounds not used in Croatian. Native Croatian speakers learning Spanish 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.