In historical linguistics, 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.

There are two types:

Metaphony is closely related to some other linguistic concepts: