Consonant mutation is the phenomenon in which a
consonant in a
word is changed according to its
morphological and/or
syntactic environment.
Mutation phenomena are found in languages around the world. The prototypical example of consonant mutation is the initial consonant mutation of all modern Celtic languages. Initial consonant mutation is also found in Indonesian or Malay, in Southern Paiute and in several West African languages such as Fula. The Nilotic language Dholuo, spoken in Kenya, shows mutation of stem-final consonants, as does English to a small extent. Mutation of initial, medial, and final consonants is found in Modern Hebrew. Japanese exhibits word medial consonant mutation involving voicing, rendaku, in many compounds.
English has a no longer productive process of voicing stem-final fricatives, which is encountered both in noun-verb pairs and in the formation of plural nouns.
The voicing alternation found in plural formation is losing ground in the modern language, and of the alternations listed below many speakers retain only the [f-v] pattern, which is supported by the orthography. This voicing is a relic of Old English, where each vowel was pronounced. Unvoiced consonants between voiced vowels were 'colored' with voicing. As the language became more analytic and less inflectional, final vowels/syllables stopped being pronounced. For example, modern knives is a one syallable word instead of a two syllable word, with the vowel 'e' not being pronounced. However, the voicing of the [f] to [v] still occurs.
