Phoneme is the smallest speech-sound unit that affects or differentiates meaning in a given language. Sounds examined as part of the language system are phonemes.
A phoneme is recognized as distinct from other sounds. When a phoneme is contrasted with another phoneme, the difference can be distinguished as a different word.
The following illustrates how changing a single phoneme affects word meaning: /k/ cook, /h/ hook, /b/ book, /t/ took. A single phoneme may correspond to one or more graphemes (written letters), as in “true” and “through, ” which differ only in the substitution of the phoneme /θ/for the phoneme “t. ” Another example is the phoneme /t/ distinguishes between “me” and “meat”