A phoneme is the smallest unit of sound in a language that can change meaning. English has about 44 phonemes despite having only 26 letters in its alphabet. The sounds 'p' and 'b' are different phonemes in English — changing 'pit' to 'bit' changes the meaning. Different languages have different numbers of phonemes, ranging from 11 (Rotokas of Papua New Guinea) to over 100 (some Khoisan languages).