Aspirated and unaspirated consonants

Ten pairs of Bangla consonants are written differently, sound nearly identical to an English ear, and differ by one thing: whether a puff of air follows the consonant.

English does this without meaning to — the p in “pin” carries a puff, the p in “spin” does not. In Bangla that difference changes the letter, and the word.

A useful test: hold a hand in front of your mouth. The aspirated letter in each pair should move the air noticeably more than its partner.