I was using English words to teach Malayalam consonants when I noticed that Malayalam has separate characters for the alveolar and retroflex versions of the same consonant. But I also noticed that these retroflex versions do exist in English as well (I could be wrong), just that there are no separate representations for them.
So, to teach my students the difference between an alveolar n and a retroflex n using English words, I told them that generally in English if its preceded by front vowels, the consonant gets an alveolar tongue placement, and retroflex if its preceded by back vowels.
e.g. the tongue placement for the n in fan, fence, fin is different from that in phone, funny.
Similarly for the l sounds in fill, fell, ally Vs fall, full And so on for t (pat vs pot) and d (adapt vs odd) as well.
However, I dont see a representation for these retroflex-y sounds in the 44-phonemes of English. Could I be wrong? Could this just be attributed to me being a native of South Asia where 'retroflexing' is very common?