Phonology

Study of sound patterns within languages.

Diachronic (historical) phonology traces and analyzes changes in speech sounds and sound systems over time (e.g., the process by which sea and see, once pronounced with different vowel sounds, have come to be pronounced alike). Synchronic (descriptive) phonology investigates sound patterns at a single stage in a language's development, to identify which ones can occur and in what position (in English, for example, nt and rk appear within or at the end of words but not at the beginning).