Editing Sound change (section)

{{Short description|Process of language change that affects pronunciation or sound system structure}}
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{{Sound change}}
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In [[historical linguistics]], a '''sound change''' is a [[language change|change]] in the [[pronunciation]] of a language. A sound change can involve the replacement of one speech sound (or, more generally, one [[distinctive feature|phonetic feature]] value) by a different one (called '''phonetic change''') or a more general change to the speech sounds that exist (''[[phonological change]]''), such as the merger of two sounds or the creation of a new sound. A sound change can eliminate the affected sound, or a new sound can be added. Sound changes can be environmentally conditioned if the change occurs in only some [[phonetic environment|sound environments]], and not others.

The term "sound change" refers to [[historical linguistics|diachronic]] changes, which occur in a language's sound system. On the other hand, "[[alternation (linguistics)|alternation]]" refers to changes that happen [[synchronic analysis|synchronically]] (within the language of an individual speaker, depending on the neighbouring sounds) and do not change the language's [[underlying representation|underlying system]] (for example, the ''-s'' in the [[English plural]] can be pronounced differently depending on the preceding sound, as in ''bet''[s], ''bed''[z], which is a form of alternation, rather than sound change). Since "sound change" can refer to the historical introduction of an alternation (such as postvocalic /k/ in the [[Tuscan dialect]], which was once [k] as in ''di'' [k]''arlo'' 'of Carlo' but is now [h] ''di'' [h]''arlo'' and alternates with [k] in other positions: ''con'' [k]''arlo'' 'with Carlo'), that label is inherently imprecise and must often be clarified as referring to either phonemic change or restructuring.

Research on sound change is usually conducted under the working assumption that it is ''regular'', which means that it is expected to apply mechanically whenever its structural conditions are met, irrespective of any non-phonological factors like the meaning of the words that are affected. Apparent exceptions to regular change can occur because of dialect borrowing, grammatical analogy, or other causes known and unknown, and some changes are described as "sporadic" and so they affect only one or a few particular words, without any apparent regularity.

The [[Neogrammarian]] linguists of the 19th century introduced the term '''sound law''' to refer to rules of regular change, perhaps in imitation of the laws of physics,<ref>Sihler, p. 50</ref> and the term "law" is still used in referring to specific sound rules that are named after their authors like [[Grimm's law]], [[Grassmann's law]], [[:Category:Sound laws|etc.]] Real-world sound laws often admit exceptions, but the expectation of their regularity or absence of exceptions is of great [[heuristic]] value{{explain |date=August 2024 |reason=unclear why acknowledging exceptions makes sounds changes less understandable or would prevent the application of the comparative method}} by allowing historical linguists to define the notion of ''regular correspondence'' by the [[comparative method]].{{citation needed|date=August 2024}}

Each sound change is limited in space and time and so it functions in a limited area (within certain [[dialects]]) and for a limited period of time. For those and other reasons, the term "sound law" has been criticized for implying a universality that is unrealistic for sound change.<ref>"The French phoneticians and the Fino-Ugric linguists" are examples according to Anttila, p. 85.</ref>

A sound change that affects the phonological system or the number or the distribution of its [[phonemes]] is a [[phonological change]].