A Phoneme is a Speech sound .It's the smallest unit of sound that distinguishes one word from another. Since sounds cannot be written , we use letters to represent or stand for the sounds .A grapheme is the written representation ( a letter or cluster of letter ) of one sound .It is generally agreed that there are approximately 44 sounds in English ,with some variation dependent on accent and articulation .The 44 English phonemes are represented by the 26 letters of the alphabet individually and in combination.