What this means for learners
Santali and Malayalam share 32 sounds — roughly 56% of Malayalam's inventory overlaps with Santali. Shared sounds are ones a speaker already knows from their native language and will generally produce and perceive accurately without explicit training.
The 21 sounds found only in Malayalam represent the greatest pronunciation challenge for Santali 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, Santali has 25 sounds not used in Malayalam. Native Malayalam speakers learning Santali 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.