Struggling to hear the difference between dental and retroflex consonants in conversations

I’m an intermediate learner and I can read Devanagari fairly well, but my listening comprehension completely falls apart when native speakers use retroflex sounds like 'ट' (ṭa) vs 'त' (ta). It all sounds the same to me in fast speech. How do I train my ears to stop filtering these out so I can actually distinguish words like 'tola' and 'ṭola'? I am asking specifically about learning Marathi, not a generic study routine.