What this means for learners
BAI and Polish share 17 sounds — roughly 46% of Polish's inventory overlaps with BAI. Shared sounds are ones a speaker already knows from their native language and will generally produce and perceive accurately without explicit training.
The 20 sounds found only in Polish represent the greatest pronunciation challenge for BAI 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, BAI has 12 sounds not used in Polish. Native Polish speakers learning BAI 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.