What this means for learners
Santali and Maithili share 31 sounds — roughly 54% of Maithili'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 20 sounds found only in Maithili 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 26 sounds not used in Maithili. Native Maithili 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.