sound change/law/shift

Terms used in HISTORICAL LINGUISTICS to describe the changes in a LANGUAGE’S SOUND SYSTEM over a period of time. Many types of sound change have been recognized, e.g. whether the change affects the total number of PHONEMES (as when two phonemes MERGE into one, or one phoneme splits into two) or affects only the ALLOPHONES of a phoneme. Particular attention is paid to the nature of the ENVIRONMENTS which can be shown to restrict (or ‘condition’) the sound change. When a series of related sound changes takes place at a particular stage of a language’s history, the change is known as a sound shift, e.g. a VOWEL shift (as took place between Middle and Early Modern English – the Great Vowel Shift) or a CONSONANT shift (as in several of the correspondences between Latin and English). A regular series of changes is traditionally referred to in COMPARATIVE PHILOLOGY as a sound law – one hypothesis about such ‘laws’ (the NEOGRAMMARIAN hypothesis) being that they had no exceptions, i.e. at a given time all WORDS containing a sound in a given PHONETIC environment would change in the same way, and any which did not could be explained by reference to a further law. Several apparent exceptions to the initial statement of such laws came to be explained by investigations which were carried out working on this premise.