historical linguistics Historical linguistics, also termed diachronic linguistics, is the scientific study of language change over time. Principal concerns of historical linguistics include: # to describe and account for observed changes in particular languages # ...

, metaphony is a class of sound change in which one vowel in a word is influenced by another in a process of assimilation. The sound change is normally "long-distance" in that the vowel triggering the change may be separated from the affected vowel by several consonants, or sometimes even by several syllables. For more discussion, see the article on

vowel harmony In phonology, vowel harmony is an assimilatory process in which the vowels of a given domain – typically a phonological word – have to be members of the same natural class (thus "in harmony"). Vowel harmony is typically long distance, mea ...

. There are two types: *''Progressive'' (or ''left-to-right'') metaphony, in which a vowel towards the beginning of a word influences a subsequent vowel. *''Regressive'' (or ''right-to-left'') metaphony, in which a vowel towards the end of the word influences a preceding vowel. Metaphony is closely related to some other linguistic concepts: *''

Vowel harmony In phonology, vowel harmony is an assimilatory process in which the vowels of a given domain – typically a phonological word – have to be members of the same natural class (thus "in harmony"). Vowel harmony is typically long distance, mea ...

'' is sometimes used synonymously with metaphony. Usually, however, "vowel harmony" refers specifically to a synchronic process operating in a particular language, normally requiring all vowels in a word to agree in a particular feature (e.g.

vowel height A vowel is a syllabic speech sound pronounced without any stricture in the vocal tract. Vowels are one of the two principal classes of speech sounds, the other being the consonant. Vowels vary in quality, in loudness and also in quantity (le ...

vowel backness A vowel is a syllabic speech sound pronounced without any stricture in the vocal tract. Vowels are one of the two principal classes of speech sounds, the other being the consonant. Vowels vary in quality, in loudness and also in quantity (leng ...

). Most commonly, the triggering vowel is in the first syllable of the word (i.e., this is a type of progressive metaphony), as in Turkish,

Finnish Finnish may refer to: * Something or someone from, or related to Finland * Culture of Finland * Finnish people or Finns, the primary ethnic group in Finland * Finnish language, the national language of the Finnish people * Finnish cuisine See also ...

or Hungarian. In some cases, however, the triggering vowel is in the last syllable, typically a suffix, as in many varieties of Andalusian Spanish. *'' Umlaut'' refers to regressive metaphony, usually specifically of a

diachronic Synchrony and diachrony are two complementary viewpoints in linguistic analysis. A ''synchronic'' approach (from grc, συν- "together" and "time") considers a language at a moment in time without taking its history into account. Synchronic l ...

type operating in the history of a language. The term "umlaut" is found especially in the

Germanic languages The Germanic languages are a branch of the Indo-European language family spoken natively by a population of about 515 million people mainly in Europe, North America, Oceania and Southern Africa. The most widely spoken Germanic language, E ...

(see Germanic umlaut). In some other languages, other terms are used instead for the same process (e.g. '' affection'' in

Old Irish Old Irish, also called Old Gaelic ( sga, Goídelc, Ogham script: ᚌᚑᚔᚇᚓᚂᚉ; ga, Sean-Ghaeilge; gd, Seann-Ghàidhlig; gv, Shenn Yernish or ), is the oldest form of the Goidelic/Gaelic language for which there are extensive writt ...

, simply ''metaphony'' in the

Romance languages The Romance languages, sometimes referred to as Latin languages or Neo-Latin languages, are the various modern languages that evolved from Vulgar Latin. They are the only extant subgroup of the Italic languages in the Indo-European language ...