What this means for learners
Assamese and Oriya share 28 sounds — roughly 65% of Oriya's inventory overlaps with Assamese. Shared sounds are ones a speaker already knows from their native language and will generally produce and perceive accurately without explicit training.
The 15 sounds found only in Oriya represent the greatest pronunciation challenge for Assamese 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, Assamese has 9 sounds not used in Oriya. Native Oriya speakers learning Assamese 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.