View source for Consonant mutation

{{Short description|Sound change happening in linguistics}}
{{More citations needed|date=November 2020}}
{{Sound change}}
{{IPA notice}}
'''Consonant mutation''' is change in a [[consonant]] in a [[word (linguistics)|word]] according to its [[morphology (linguistics)|morphological]] or [[syntax|syntactic]] environment.

Mutation occurs in languages around the world. A prototypical example of consonant mutation is the initial consonant mutation of all modern [[Celtic languages]]. Initial consonant mutation is also found in [[Indonesian language|Indonesian]] or [[Malay language|Malay]], in [[Nivkh languages|Nivkh]], in [[Uto-Aztecan languages|Southern Paiute]] and in several [[West African languages]] such as [[Fula language|Fula]]. The [[Nilotic languages|Nilotic language]] [[Dholuo]], spoken in [[Kenya]], shows mutation of stem-final consonants, as does [[English language|English]] to a small extent. Mutation of initial, medial and final consonants is found in [[Modern Hebrew]]. Also, [[Japanese language|Japanese]] exhibits word medial consonant mutation involving voicing, ''[[rendaku]]'', in many compounds. [[Uralic languages]] like [[Finnish language|Finnish]] show [[consonant gradation]], a type of consonant mutation.

== Similar sound changes ==
Initial consonant mutation must not be confused with [[sandhi]], which can refer to word-initial alternations triggered by their [[phonology|phonological]] environment, unlike mutations, which are triggered by their [[morphosyntactic]] environment. Some examples of word-initial sandhi are listed below.
*[[Spanish language|Spanish]]: {{IPA|[b, d, ɡ]}}, occurring after [[nasal consonant|nasals]] and pause, alternate with {{IPA|[β, ð, ɣ]}}, occurring after [[vowel]]s and [[liquid consonant]]s. Example: un ['''b''']arco 'a boat', mi ['''β''']arco 'my boat'. This also occurs in [[Hebrew language|Hebrew]] (as [[Begadkefat|begedkefet]], an [[Acronyms in Hebrew|acronym]] for the consonants this affects), [[Aramaic language|Aramaic]], and [[Tamil language|Tamil]].
*Scottish Gaelic: in some dialects, stops in stressed syllables are voiced after nasals, e.g. cat {{IPA|['''kʰ'''aht]}} 'a cat', an cat {{IPA|[əŋ '''ɡ'''aht]}} 'the cat'.

Sandhi effects like these (or other phonological processes) are usually the historical origin of morphosyntactically triggered mutation. For example, English fricative mutation (specifically, voicing) in words such as ''house'' [haus], plural ''houses'' [hauzɪz], and the verb ''to house'' [hauz] originates in an [[allophone|allophonic]] alternation of [[Old English language|Old English]], where a voiced fricative occurred between vowels (or before voiced consonants), and a voiceless one occurred initially or finally, and also when adjacent to voiceless consonants. Old English infinitives ended in ''-(i)an'' and plural nouns (of Class One nouns) ended in ''-as''. Thus, ''hūs'' 'a house' had {{IPA|[s]}}, and ''hūsian'' 'house (verb)' had {{IPA|[z]}}; however,  the plural of ''hūs'' was ''hūs'', being a neuter noun of the strong a-stem class. During the Middle English period, ''hous''~''hus'', as part of the loss of gender and erosion of endings, developed plural variation, retaining ''hous'' [hu:s], the dative plural ''housen'' [hu:zən], which became extended to a general plural, and over time taking on the ''es'' plural from Old English Class 1 nouns, thus ''houses'' [hu:zəz].  After most endings were lost in English, and the contrast between voiced and voiceless fricatives partly phonemicized (largely due to the influx of [[French language|French]] loanwords), the alternation was morphologized.

== Examples ==

=== English ===
{{See also|Consonant voicing and devoicing#English}}
In Old English, velar stops were [[Palatalization (sound change)|palatalized]] in certain cases but not others. That resulted in some alternations, many of which have been [[morphological leveling|levelled]], but traces occur in some word doublets such as ''di'''tch''''' {{IPA|/dɪ'''tʃ'''/}} and ''di'''k'''e'' {{IPA|/daɪ'''k'''/}}.

In the past tense of certain verbs, English also retains traces of several ancient sound developments such as *kt > *xt and *ŋx > *x; many of them have been further complicated by the loss of {{IPA|/x/}} in Middle English.
* ''see'''k''''' {{IPA|/siː'''k'''/}} : ''sou'''gh'''t'' {{IPA|/sɔːt/}}
* ''thi'''nk''''' {{IPA|/θɪ'''ŋk'''/}} : ''thou'''gh'''t'' {{IPA|/θɔːt/}}

The pair ''tea'''ch''''' {{IPA|/tiː'''t͡ʃ'''/}} : ''tau'''gh'''t'' {{IPA|/tɔːt/}} has a combination of both this and palatalization.

A second palatalization, called [[yod-coalescence]], occurs in loanwords from [[Latin]]. One subtype affects the [[sibilant consonant]]s: earlier {{IPA|/sj/}} and {{IPA|/zj/}} were palatalized, leading to an alternation between alveolar {{IPA|/s z/}} and postalveolar {{IPA|/ʃ ʒ/}}.
* ''confe'''ss''''' {{IPA|/kənˈfɛ'''s'''/}} : ''confe'''ssi'''on'' {{IPA|/kənˈfɛ'''ʃ'''ən/}}
* ''fu'''s'''e'' {{IPA|/fjuː'''z'''/}} : ''fu'''si'''on'' {{IPA|/ˈfjuː'''ʒ'''ən/}}

Another unproductive layer results from the Vulgar Latin palatalization of velar stops before front vowels. It is thus imported from the Romance languages, and {{IPA|/k ɡ/}} alternate with {{IPA|/s dʒ/}}.
* ''indu'''c'''e'' {{IPA|/ɪnˈdjuː'''s'''/}} : ''indu'''c'''tion'' {{IPA|/inˈdʌ'''k'''ʃən/}}
* ''ma'''g'''ic'' {{IPA|/ˈmæ'''dʒ'''ɪk/}} : ''ma'''g'''us'' {{IPA|/meɪ'''ɡ'''əs/}}

A combination of inherited and loaned alternation also occurs: an alternation pattern *t : *sj was brought over in Latinate loanwords, which in English was then turned into an alternation between {{IPA|/t/}} and {{IPA|/ʃ/}}.
* ''ac'''t''''' {{IPA|/æk'''t'''/}} : ''ac'''ti'''on'' {{IPA|/ˈæk'''ʃ'''ən/}}

=== Celtic languages ===
{{Further|Breton mutations|Cornish grammar#Initial consonant mutation|Irish initial mutations|Manx language#Initial consonant mutations|Scottish Gaelic phonology#Lenition and spelling}}
The [[Insular Celtic languages]] are well-known for their initial consonant mutations.<ref>{{cite book|last=Ball|first=M. J.|author2=N. Müller|title=Mutation in Welsh|location=London|publisher=Routledge|year=1992|isbn=0-415-03165-6}}</ref><ref>{{cite book|last=Fife|first=James|author2=Gareth King|chapter=Celtic (Indo-European)|title=The Handbook of Morphology|editor=Andrew Spencer |editor2=Arnold M. Zwicky |pages=477–99|location=Oxford |publisher=Blackwell|year=1998|isbn=0-631-22694-X}}</ref> The individual languages vary on the number of mutations available: [[Scottish Gaelic]] has one, [[Irish language|Irish]] and [[Manx language|Manx]] have two, [[Welsh language|Welsh]], [[Cornish language|Cornish]] and [[Breton language|Breton]] have four (if mixed mutations are counted). Cornish and Breton have so-called mixed mutations; a trigger causes one mutation to some sounds and another to other sounds. Welsh also has a mixed mutation (triggered by ''na'', ''ni'' and ''oni''). The languages vary on the environments for the mutations, but some generalizations can be made. Those languages all have feminine singular nouns  mutated after the definite article, with adjectives mutated after feminine singular nouns. In most of the languages, the [[possessive determiner]]s trigger various mutations. Here are some examples from Breton, Cornish, Irish, Scottish Gaelic, and Welsh:

{| class="wikitable" style="margin:1em auto;"
! Breton !! Cornish !! Welsh !! Irish !! Scottish Gaelic !! Gloss
|-
| gwreg || gwreg || gwraig || bean || bean || ''woman''/''wife''
|-
| bras <!--compare with mor in old breton --> || bras|| mawr || mór || mòr || ''big''
|-
| ar '''w'''reg '''v'''ras || an '''w'''reg '''v'''ras || yr '''w'''raig '''f'''awr || an '''bh'''ean '''mh'''ór || a' '''bh'''ean '''mh'''òr || ''the big woman''
|-
| kazh || kath || cath || cat || cat || ''cat''
|-
| e '''g'''azh || y '''g'''ath || ei '''g'''ath || a '''ch'''at || a '''ch'''at ||''his cat''
|-
| he '''c'h'''azh || hy '''h'''ath || ei '''ch'''ath || a '''c'''at || a '''c'''at || ''her cat''
|-
| o '''c'h'''azh || aga '''h'''ath || eu '''c'''ath || a '''gc'''at || an '''c'''at || ''their cat''
|}

Older textbooks on Gaelic sometimes refer to the ''c → ch'' mutation as "aspiration", but it is not [[aspiration (phonetics)|aspiration]] in the sense of the word used by modern phoneticians, and linguists prefer to speak of [[lenition]] here.

Historically, the Celtic initial mutations originated from [[progressive assimilation]] and [[sandhi]] phenomena between adjacent words. For example, the mutating effect of the conjunction ''a'' 'and' is from the word once having the form *ak, and the final consonant influenced the following sounds.<ref>Ternes, Elmar. 1986. A Grammatical hierarchy of joining. In: Andersen, Henning. Sandhi phenomena in the languages of Europe. P.17-18</ref>

==== Welsh ==== 
{{further|Literary Welsh morphology#Initial consonant mutation|Colloquial Welsh morphology#Initial consonant mutation}}
[[Welsh language|Welsh]] has three main classes of initial consonant mutation: ''soft mutation'' ({{langx|cy|treiglad meddal}}); ''nasal mutation'' ({{langx|cy|treiglad trwynol}}); and ''aspirate mutation'', which is sometimes called ''spirant mutation'' ({{langx|cy|treiglad llaes}}). The fourth category is ''mixed mutation'', which calls for an ''aspirate mutation'' if possible but otherwise a ''soft mutation''. The following tables show the range of Welsh mutations with examples. A blank cell indicates that no change occurs.

{|
|width=300|
{| class="wikitable"
|+Mutation scheme
|- style="background: #efefef;"
! Radical
! Soft
! Nasal
! Aspirate
|-
| p
| b
| mh {{IPA|/m̥/}}
| ph {{IPA|/f/}}
|-
| t
| d
| nh {{IPA|/n̥/}}
| th {{IPA|/θ/}}
|-
| c {{IPA|/k/}}
| g
| ngh {{IPA|/ŋ̊/}}
| ch {{IPA|/χ/}}
|-
| b
| f {{IPA|/v/}}
| m
| 
|-
| d
| dd {{IPA|/ð/}}
| n
| 
|-
| g
| {{IPA|∅}}*
| ng {{IPA|/ŋ/}}
|
|-
| m
| f {{IPA|/v/}}
| 
| 
|-
| ll {{IPA|/ɬ/}}
| l
|
|
|-
| rh {{IPA|/r̥/}}
| r
|
|
|-
| ts {{IPA|/t͡ʃ/}}
| j {{IPA|/d͡ʒ/}}
|
|
|}
|width=50|

|rowspan=2 valign=top|
{| class="wikitable"
|+Examples
|- style="background: #efefef;"
! Radical
! Soft
! Nasal
! Aspirate
! English
|-
| '''p'''lant {{IPA|/plant/}}
| '''b'''lant {{IPA|/blant/}}
| '''mh'''lant {{IPA|/m̥lant/}}
| '''ph'''lant {{IPA|/flant/}}
| ''children''
|-
| '''t'''ref {{IPA|/treː(v)/}}<br />'''t'''ŷ {{IPA|/tiː/}}
| '''d'''ref {{IPA|/dreː(v)/}}<br />'''d'''ŷ {{IPA|/diː/}}
| '''nh'''ref {{IPA|/n̥reː(v)/}}<br />'''nh'''ŷ {{IPA|/n̥iː/}}
| '''th'''ref {{IPA|/θreː(v)/}}<br />'''th'''ŷ {{IPA|/θiː/}}
| ''town''<br />''house''
|-
| '''c'''oeden {{IPA|/kɔi̯dɛn/}}
| '''g'''oeden {{IPA|/ɡɔi̯dɛn/}}
| '''ngh'''oeden {{IPA|/ŋ̊ɔi̯dɛn/}}
| '''ch'''oeden {{IPA|/χɔi̯dɛn/}}
| ''tree''
|-
| '''b'''rawd {{IPA|/braʊ̯d/}}
| '''f'''rawd {{IPA|/vraʊ̯d/}}
| '''m'''rawd {{IPA|/mraʊ̯d/}}
| 
| ''brother''
|-
| '''d'''ŵr {{IPA|/duːr/}}
| '''dd'''ŵr {{IPA|/ðuːr/}}
| '''n'''ŵr {{IPA|/nuːr/}}
| 
| ''water''
|-
| '''g'''waith {{IPA|/ɡwai̯θ/}}<br />'''g'''las {{IPA|/ɡlas/}}<br />'''g'''orsaf {{IPA|/ɡɔrsa(v)/}}
| '''w'''aith {{IPA|/wai̯θ/}}<br />'''l'''as {{IPA|/las/}}<br />'''o'''rsaf {{IPA|/ɔrsa(v)/}}
| '''ng'''waith {{IPA|/ŋwai̯θ/}}<br />'''ng'''las {{IPA|/ŋlas/}}<br />'''ng'''orsaf {{IPA|/ŋɔrsa(v)/}}
|
| ''work''<br />''blue''<br />''station''
|-
| '''m'''awr {{IPA|/maʊ̯r/}}
| '''f'''awr {{IPA|/vaʊ̯r/}}
| 
| 
| ''big, large''
|-
| '''ll'''an {{IPA|/ɬan/}}
| '''l'''an {{IPA|/lan/}}
|
|
| ''parish''
|-
| '''rh'''ywbeth {{IPA|/r̥ɪʊ̯bɛθ/}}
| '''r'''ywbeth {{IPA|/rɪʊ̯bɛθ/}}
|
|
| ''something''
|-
| '''ts'''ips {{IPA|/t͡ʃɪps/}}
| '''j'''ips {{IPA|/d͡ʒɪps/}}
|
|
| ''chips''
|}
|-
|{{asterisk}}Soft mutation causes initial {{IPA|/ɡ/}} to be deleted. For example, {{lang|cy|gardd}} "garden" becomes {{lang|cy|yr ardd}} "the garden", and {{lang|cy|gwaith}} "work" becomes {{lang|cy|ei waith}} "his work".
|}

The mutation ''ts'' → ''j'' corresponds to the ''t'' → ''d'' mutation and reflects a change heard in modern words borrowed from English. Borrowed words like {{lang|cy|tsips/jips}} (chips) can often be heard in Wales. {{lang|cy|Dw i'n mynd i gael tsips}} 'I'm going to get (some) chips'; {{lang|cy|Mae gen i jips}} 'I have chips'. However, the ''ts'' → ''j'' mutation is not usually included the classic list of Welsh mutations and is rarely taught in formal classes. Nevertheless, it is a part of the colloquial language and is used by native speakers.

===== ''h''-prothesis =====
[[Prothesis (linguistics)|h-''prothesis'']] is a feature in Welsh in which a vowel-initial word becomes ''h''-initial. It occurs after the possessive pronouns {{lang|cy|ei}} 'her', {{lang|cy|ein}} 'our', and {{lang|cy|eu}} 'their': {{lang|cy|oedran}} 'age', {{lang|cy|ei '''h'''oedran}} 'her age' (cf. {{lang|cy|ei oedran}} 'his age'). It also occurs with {{lang|cy|ugain}} 'twenty' after {{lang|cy|ar}} 'on' in the traditional counting system: {{lang|cy|un ar '''h'''ugain}} 'twenty-one', literally "one on twenty".

==== Irish ====
{{further|Irish initial mutations}}
[[Irish language|Irish]] has two consonant mutations: ''[[lenition]]'' ({{Langx|ga|séimhiú}} {{IPA|ga|ˈʃeːvʲuː|}}) and ''eclipsis'' ({{Lang|ga|urú}} {{IPA|ga|ˈʊɾˠuː|}}).

===== Lenition =====
Lenition ({{lang|ga|séimhiú}}) is indicated by an {{vr|h}} following the consonant in question or, in some older typefaces and texts, by an [[dot (diacritic)|overdot]] ({{vr|◌̇}}) above the letter that has undergone lenition. The effects of lenition are as follows:

# A stop becomes a fricative. [[Voice (phonetics)|Voicing]] is retained, as is [[place of articulation]] except for the [[coronal consonant|coronals]].
#*{{IPA|/pˠ/}} → {{IPA|/fˠ/}}
#*{{IPA|/pʲ/}} → {{IPA|/fʲ/}}
#*{{IPA|/t̪ˠ/}} → {{IPA|/h/}}
#*{{IPA|/tʲ/}} → {{IPA|/h/}}
#*{{IPA|/k/}} → {{IPA|/x/}}
#*{{IPA|/c/}} → {{IPA|/ç/}}
#*{{IPA|/bˠ/}} → {{IPA|/w/}}, {{IPA|/v/}}
#*{{IPA|/bʲ/}} → {{IPA|/vʲ/}}
#*{{IPA|/d̪ˠ/}} → {{IPA|/ɣ/}}
#*{{IPA|/dʲ/}} → {{IPA|/j/}}
#*{{IPA|/ɡ/}} → {{IPA|/ɣ/}}
#*{{IPA|/ɟ/}} → {{IPA|/j/}}
#*{{IPA|/mˠ/}} → {{IPA|/w/}}
#*{{IPA|/mʲ/}} → {{IPA|/vʲ/}}
# {{IPA|/sˠ/}} and {{IPA|/ʃ/}} become {{IPA|/h/}}, but {{IPA|/sˠp(ʲ)/}}, {{IPA|/sˠm(ʲ)/}}, {{IPA|/sˠt̪ˠ/}}, {{IPA|/ʃtʲ/}}, {{IPA|/sˠk/}}, and {{IPA|/ʃc/}} do not mutate.
# {{IPA|/fˠ/}} and {{IPA|/fʲ/}} are deleted.

{| class="wikitable"
|+Examples
|-
!Unmutated
!Lenition
!Gloss
|-
|{{Lang|ga|peann}} {{IPA|/pʲaːn̪ˠ/}}
|{{Lang|ga|pheann}} {{IPA|/fʲaːn̪ˠ/}}
|"pen"
|-
|{{Lang|ga|teach}} {{IPA|/tʲax/}}
|{{Lang|ga|theach}} {{IPA|/hax/}}
|"house"
|-
|{{Lang|ga|ceann}} {{IPA|/caːn̪ˠ/}}
|{{Lang|ga|cheann}} {{IPA|/çaːn̪ˠ/}}
|"head"
|-
|{{Lang|ga|bean}} {{IPA|/bʲanˠ/}}
|{{Lang|ga|bhean}} {{IPA|/vʲanˠ/}}
|"woman"
|-
|{{Lang|ga|droim}} {{IPA|/d̪ˠɾˠiːmʲ/}}
|{{Lang|ga|dhroim}} {{IPA|/ɣɾˠiːmʲ/}}
|"back"
|-
|{{Lang|ga|glúin}} {{IPA|/ɡl̪ˠuːnʲ/}}
|{{Lang|ga|ghlúin}} {{IPA|/ɣl̪ˠuːnʲ/}}
|"knee"
|-
|{{Lang|ga|máthair}} {{IPA|/mˠaːhəɾʲ/}}
|{{Lang|ga|mháthair}} {{IPA|/waːhəɾʲ/}}
|"mother"
|-
|{{Lang|ga|súil}} {{IPA|/sˠuːlʲ/}}
|{{Lang|ga|shúil}} {{IPA|/huːlʲ/}}
|"eye"
|-
|{{Lang|ga|freagra}} {{IPA|/fʲɾʲaɡɾˠə/}}
|{{Lang|ga|fhreagra}} {{IPA|/ɾʲaɡɾˠə/}}
|"answer"
|}

===== Eclipsis =====
The following tables show how eclipsis affects the start of words. Eclipsis is represented in the orthography by adding a letter, or occasionally two letters, to the start of the word. If the word is to be capitalised, the original first letter is capitalised, not the letter or letters added for eclipsis, e.g. the {{vr|bhF}} in {{lang|ga|Amhrán na '''bhF'''iann}}, Ireland's national anthem.

{| class="wikitable"
!Sound change
!Unmutated
!Eclipsis
!Gloss
!Notes
|-
|{{IPA|/pˠ/}} → {{IPA|/bˠ/}}
|{{Lang|ga|práta}} {{IPA|/pˠɾˠaːt̪ˠə/}}
|{{Lang|ga|bpráta}} {{IPA|/bˠɾˠaːt̪ˠə/}}
|"potato"
|rowspan="8"|A voiceless stop or /fˠ, fʲ/ is voiced.
|-
|{{IPA|/pʲ/}} → {{IPA|/bʲ/}}
|{{Lang|ga|peann}} {{IPA|/pʲaːnˠ/}}
|{{Lang|ga|bpeann}} {{IPA|/bʲaːnˠ/}}
|"pen"
|-
|{{IPA|/t̪ˠ/}} → {{IPA|/d̪ˠ/}}
|{{Lang|ga|tráta}} {{IPA|/t̪ˠɾˠaːt̪ˠə/}}
|{{Lang|ga|dtráta}} {{IPA|/d̪ˠɾˠaːt̪ˠə/}}
|"tomato"
|-
|{{IPA|/tʲ/}} → {{IPA|/dʲ/}}
|{{Lang|ga|teanga}} {{IPA|/tʲaŋ(ɡ)ə/}}
|{{Lang|ga|dteanga}} {{IPA|/dʲaŋ(ɡ)ə/}}
|"tongue"
|-
|{{IPA|/k/}} → {{IPA|/ɡ/}}
|{{Lang|ga|cat}} {{IPA|/kat̪ˠ/}}
|{{Lang|ga|gcat}} {{IPA|/gat̪ˠ/}}
|"cat"
|-
|{{IPA|/c/}} → {{IPA|/ɟ/}}
|{{Lang|ga|ceann}} {{IPA|/caːn̪ˠ/}}
|{{Lang|ga|gceann}} {{IPA|/ɟaːn̪ˠ/}}
|"head"
|-
|{{IPA|/fˠ/}} → {{IPA|/w/}}
|{{Lang|ga|focal}} {{IPA|/fˠɔkəlˠ/}}
|{{Lang|ga|bhfocal}} {{IPA|/wɔkəlˠ/}}
|"word"
|-
|{{IPA|/fʲ/}} → {{IPA|/vʲ/}}
|{{Lang|ga|freagra}} {{IPA|/fʲɾʲaɡɾˠə/}}
|{{Lang|ga|bhfreagra}} {{IPA|/vʲɾʲaɡɾˠə/}}
|"answer"
|-
|{{IPA|/bˠ/}} → {{IPA|/mˠ/}}
|{{Lang|ga|bainne}} {{IPA|/bˠan̠ʲə/}}
|{{Lang|ga|mbainne}} {{IPA|/mˠan̠ʲə/}}
|"milk"
|rowspan="6"|A voiced stop becomes a nasal.
|-
|{{IPA|/bʲ/}} → {{IPA|/mʲ/}}
|{{Lang|ga|bean}} {{IPA|/bʲanˠ/}}
|{{Lang|ga|mbean}} {{IPA|/mʲanˠ/}}
|"woman"
|-
|{{IPA|/d̪ˠ/}} → {{IPA|/n̪ˠ/}}
|{{Lang|ga|droim}} {{IPA|/d̪ˠɾˠiːmʲ/}}
|{{Lang|ga|ndroim}} {{IPA|/n̪ˠɾˠiːmʲ/}}
|"back"
|-
|{{IPA|/dʲ/}} → {{IPA|/n̠ʲ/}}
|{{Lang|ga|dinnéar}} {{IPA|/dʲɪn̠ʲeːɾˠ/}}
|{{Lang|ga|ndinnéar}} {{IPA|/n̠ʲɪn̠ʲeːɾˠ/}}
|"dinner"
|-
|{{IPA|/ɡ/}} → {{IPA|/ŋ/}}
|{{Lang|ga|glúin}} {{IPA|/ɡɫ̪uːnʲ/}}
|{{Lang|ga|nglúin}} {{IPA|/ŋɫ̪uːnʲ/}}
|"knee"
|-
|{{IPA|/ɟ/}} → {{IPA|/ɲ/}}
|{{Lang|ga|geata}} {{IPA|/ɟat̪ˠə/}}
|{{Lang|ga|ngeata}} {{IPA|/ɲat̪ˠə/}}
|"gate"
|-
|{{IPA|/eː/}} → {{IPA|/n̠ʲeː/}}
|{{Lang|ga|éan}} {{IPA|/eːnˠ/}}
|{{Lang|ga|n-éan}} {{IPA|/n̠ʲeːnˠ/}}
|"bird"
|rowspan="2"|A vowel receives a preceding {{IPA|/n̪ˠ/}} (before {{vr|a, o, u}}), or {{IPA|/n̠ʲ/}} (before {{vr|e, i}}).
|-
|{{IPA|/iː/}} → {{IPA|/n̪ˠiː/}}
|{{Lang|ga|oíche}} {{IPA|/iːçə/}}
|{{Lang|ga|n-oíche}} {{IPA|/n̪ˠiːçə/}}
|"night"
|}

=== Russian ===
In [[Russian language|Russian]], consonant mutation and [[alternation (linguistics)|alternations]] are a very common phenomenon during [[word formation]], [[Grammatical conjugation|conjugation]] and in [[comparative adjective]]s.

The most common classes of mutations are the alternation between [[velar consonant|velar]] and [[postalveolar consonant]]s:
* {{lang|ru|к}} {{IPA|/k/}} → {{lang|ru|ч}} {{IPA|/tɕ/}}
* {{lang|ru|г}} {{IPA|/ɡ/}} → {{lang|ru|ж}} {{IPA|/ʐ/}}
* {{lang|ru|х}} {{IPA|/x/}} → {{lang|ru|ш}} {{IPA|/ʂ/}}, as in {{lang|ru|{{linktext|тихий}}}} "quiet" and {{linktext|тише}} "quieter"
*Gain or loss of [[Palatalization (sound change)|palatalization]]: {{lang|ru|{{linktext|царь}}}} "[[tsar]]" and {{lang|ru|{{linktext|царский}}}} "of the tsar" (adjective)

Other common mutations are:
*{{lang|ru|т}} {{IPA|/t/}} → {{lang|ru|ч}} {{IPA|/tɕ/}} (or less frequently щ {{IPA|/ɕː/}}), {{lang|ru|д}} {{IPA|/d/}} → {{lang|ru|ж}} {{IPA|/ʐ/}}
*{{lang|ru|з}} {{IPA|/z/}} → {{lang|ru|ж}} {{IPA|/ʐ/}}, {{lang|ru|с}} {{IPA|/s/}} → {{lang|ru|ш}} {{IPA|/ʂ/}}, {{lang|ru|ц}} {{IPA|/ts/}} → {{lang|ru|ч}} {{IPA|/tɕ/}}
*{{lang|ru|ск}} {{IPA|/sk/}} → {{lang|ru|щ}} {{IPA|/ɕː/}}: плеск → плещет "splash" / "(he) splashes", {{lang|ru|ст}} {{IPA|/st/}} → {{lang|ru|щ}} {{IPA|/ɕː/}}: свистеть → свищу "to whistle" / "I whistle"

=== Hebrew ===
Modern [[Hebrew language|Hebrew]] shows a limited set of mutation alternations, involving [[spirantization]] only.<ref>{{cite book |first=Lewis |last=Glinert |title=The Grammar of Modern Hebrew |location=Cambridge |publisher=Cambridge University Press |year=1989}}</ref> The consonants affected may be stem-initial, stem-medial, or stem-final.

{| class="wikitable"
! Radical !! Spirantized
|-
| p || f
|-
| k || x
|-
| b || v
|}
{| style="white-space:nowrap; border-style:none" cellspacing="0" cellpadding="0"
| colspan="3" |These alternations occur in [[verb]]s:
|-
|{{•}}{{Script/Hebrew|בּוֹא ← תָּבוֹא}}
|<span style="margin-left:5px;margin-right:5px;background-color:#e7e7e7">{{IPA|/'''b'''o/ → /taˈ'''v'''o/}}</span>
|("come" ([[Imperative mood|imperative]]) → "you will come"),
|-
|{{•}}{{Script/Hebrew|שָׁבַר ← נִשׁבַּר}}
|<span style="margin-left:5px;margin-right:5px;background-color:#e7e7e7">{{IPA|/ʃaˈ'''v'''aʁ/ → /niʃˈ'''b'''aʁ/}}</span>
|("broke" ([[Transitive verb|transitive]]) → "broke" ([[Intransitive verb|intransitive]]),
|-
|{{•}}{{Script/Hebrew|כָּתַב ← יִכְתֹּב}}
|<span style="margin-left:5px;margin-right:5px;background-color:#e7e7e7">{{IPA|/'''k'''aˈtav/ → /ji'''χ'''ˈtov/}}</span>
|("he wrote" → "he will write"),
|-
|{{•}}{{Script/Hebrew|זָכַר ← יִזְכֹּר}}
|<span style="margin-left:5px;margin-right:5px;background-color:#e7e7e7">{{IPA|/zaˈ'''χ'''aʁ/ → /jizˈ'''k'''oʁ/}}</span>
|("he remembered" → "he will remember"),
|-
|{{•}}{{Script/Hebrew|פָּנִית ← לִפְנוֹת}}
|<span style="margin-left:5px;margin-right:5px;background-color:#e7e7e7">{{IPA|/'''p'''aˈnit/ → /li'''f'''ˈnot/}}</span>
|("you (''f.'') turned" → "to turn"),
|-
|{{•}}{{Script/Hebrew|שָׁפַטְתְּ ← לִשְׁפֹּט}}
|<span style="margin-left:5px;margin-right:5px;background-color:#e7e7e7">{{IPA|/ʃaˈ'''f'''atet/ → /liʃˈ'''p'''ot/}}</span>
|("you (''f.'') judged" → "to judge "),
|-
| colspan="3" |or in [[noun]]s:
|-
|{{•}}{{Script/Hebrew|ערב ← ערביים}}
|<span style="margin-left:5px;margin-right:5px;background-color:#e7e7e7">{{IPA|/ˈeʁe'''v'''/ → /aʁˈ'''b'''ajim/}}</span>
|("evening" → "twilight"),
|-
|{{•}}{{Script/Hebrew|מלך ← מלכה}}
|<span style="margin-left:5px;margin-right:5px;background-color:#e7e7e7">{{IPA|/ˈmele'''χ'''/ → /malˈ'''k'''a/}}</span>
|("king" → "queen"),
|-
|{{•}}{{Script/Hebrew|אלף ← אלפית}}
|<span style="margin-left:5px;margin-right:5px;background-color:#e7e7e7">{{IPA|/ˈele'''f'''/ → /alˈ'''p'''it/}}</span>
|("a thousand" → "a thousandth"),
|}
However, in Modern Hebrew, stop and fricative variants of {{Script/Hebrew|[[ב]]}}{{rtl}}, {{Script/Hebrew|[[כ]]}} and {{Script/Hebrew|[[פ]]}} are sometimes distinct phonemes:
{| style="white-space:nowrap; border-style:none" cellspacing="0" cellpadding="0"
|{{•}}{{Script/Hebrew|אִפֵּר – עִפֵר}}
|<span style="margin-left:5px;margin-right:5px;background-color:#e7e7e7">{{IPA|/iˈ'''p'''eʁ/}} – {{IPA|/iˈ'''f'''eʁ/}}</span>
|("applied make up" – "tipped ash"),
|-
|{{•}}{{Script/Hebrew|פִּסְפֵּס – פִסְפֵס}}
|<span style="margin-left:5px;margin-right:5px;background-color:#e7e7e7">{{IPA|/'''p'''isˈ'''p'''es/}} – {{IPA|/'''f'''isˈ'''f'''es/}}</span>
|("striped" – "missed"),
|-
|{{•}}{{Script/Hebrew|הִתְחַבֵּר – הִתְחַבֵר}}
|<span style="margin-left:5px;margin-right:5px;background-color:#e7e7e7">{{IPA|/hitχaˈ'''b'''eʁ/}} – {{IPA|/hitχaˈ'''v'''eʁ/}}</span>
|("connected" – "made friends (with)"),
|-
|{{•}}{{Script/Hebrew|הִשְׁתַּבֵּץ – הִשְׁתַּבֵץ}}
|<span style="margin-left:5px;margin-right:5px;background-color:#e7e7e7">{{IPA|/hiʃtaˈ'''b'''ets/}} – {{IPA|/hiʃtaˈ'''v'''ets/}}</span>
|("got integrated" – "was shocked"),
|}
For a more in depth discussion of this phenomenon, see [[Begadkefat]].

=== Japanese ===
[[Rendaku]], meaning "sequential voicing", is a mutation of the initial consonant of a non-initial component in a [[Japanese language|Japanese]] compound word:
* nigiri + sushi → nigiri'''z'''ushi ("grip (with the hand)" + "sushi" → "hand-shaped [[sushi]]")
* nigori + sake → nigori'''z'''ake ("muddy" + "rice wine" → "unfiltered [[sake]]")

=== Uralic languages ===
{{Main|Consonant gradation}}
Word-medial consonant mutation is found in several [[Uralic languages]] and has the traditional name of [[consonant gradation]]. It is pervasive, especially in the [[Samic languages|Samic]] and [[Finnic languages|Finnic]] branches.

==== Finnish ====
{{Main|Finnish consonant gradation}}
Consonant gradation involves an alternation in consonants between a strong grade in some forms of a word and a weak grade in others. The consonants subject to gradation are the plosives ({{lang|fi|p}}, {{lang|fi|t}}, {{lang|fi|k}}) that are followed by a vowel and preceded by a vowel, a sonorant ({{lang|fi|m}}, {{lang|fi|n}}, {{lang|fi|l}}, {{lang|fi|r}}), or {{lang|fi|h}}. The strong grade usually appears in an open syllable or before a long vowel.

{| class="wikitable"
! Strong !! Weak !! Example !! Notes
|-
| {{lang|fi|pp}} || {{lang|fi|p}} || {{lang|fi|pa'''pp'''i}} → {{lang|fi|pa'''p'''it}}; {{lang|fi|lam'''pp'''u}} → {{lang|fi|lam'''p'''ut}} || rowspan="3"| Long consonants become short.
|-
| {{lang|fi|tt}} || {{lang|fi|t}} || {{lang|fi|ka'''tt'''o}} → {{lang|fi|ka'''t'''ot}}; {{lang|fi|kor'''tt'''i}} → {{lang|fi|kor'''t'''it}}
|-
| {{lang|fi|kk}} || {{lang|fi|k}} || {{lang|fi|pu'''kk'''i}} → {{lang|fi|pu'''k'''it}}; {{lang|fi|pan'''kk'''i}} → {{lang|fi|pan'''k'''it}}
|-
| {{lang|fi|p}} || {{lang|fi|v}} || {{lang|fi|ta'''p'''a}} → {{lang|fi|ta'''v'''at}} || rowspan="3"|Lenition.
|-
| {{lang|fi|t}} || {{lang|fi|d}} || {{lang|fi|ka'''t'''u}} → {{lang|fi|ka'''d'''ut}}; {{lang|fi|lah'''t'''i}} → {{lang|fi|lah'''d'''et}}
|-
| rowspan="3" | {{lang|fi|k}} || {{lang|fi|∅}} || {{lang|fi|pa'''k'''o}} → {{lang|fi|paot}}
|-
| {{lang|fi|v}} || {{lang|fi|pu'''k'''u}} → {{lang|fi|pu'''v'''ut}}; {{lang|fi|ky'''k'''y}} → {{lang|fi|ky'''v'''yt}} || In the combinations {{lang|fi|-uku-}} and {{lang|fi|-yky-}}.
|-
| {{lang|fi|j}} || {{lang|fi|jäl'''k'''i}} → {{lang|fi|jäl'''j'''et}}; {{lang|fi|sul'''k'''ea}} → {{lang|fi|sul'''j'''in}} || When followed by {{lang|fi|e}} or {{lang|fi|i}} and preceded by {{lang|fi|h}}, {{lang|fi|l}} or {{lang|fi|r}}.
|-
| {{lang|fi|mp}} || {{lang|fi|mm}} || {{lang|fi|ka'''mp'''a}} → {{lang|fi|ka'''mm'''at}} || rowspan="5"| Assimilation.
|-
| {{lang|fi|nt}} || {{lang|fi|nn}} || {{lang|fi|le'''nt'''o}} → {{lang|fi|le'''nn'''ot}}
|-
| {{lang|fi|lt}} || {{lang|fi|ll}} || {{lang|fi|kie'''lt'''o}} → {{lang|fi|kie'''ll'''ot}}
|-
| {{lang|fi|rt}} || {{lang|fi|rr}} || {{lang|fi|pa'''rt'''a}} → {{lang|fi|pa'''rr'''at}}
|-
| {{lang|fi|nk}} {{IPA|/ŋk/}} || {{lang|fi|ng}} {{IPA|/ŋː/}} || {{lang|fi|ke'''nk'''ä}} → {{lang|fi|ke'''ng'''ät}}
|}

The gradation of loanwords may include gradation of the plosives that are not native to Finnish:

{| class="wikitable"
! Strong !! Weak !! Example
|-
| {{lang|fi|bb}} || {{lang|fi|b}} || {{lang|fi|lo'''bb'''aan}} → {{lang|fi|lo'''b'''ata}}
|-
| {{lang|fi|gg}} || {{lang|fi|g}} || {{lang|fi|blo'''gg'''aan}} → {{lang|fi|blo'''g'''ata}}
|}

=== Burmese ===
[[Burmese language|Burmese]] exhibits consonant mutation, in the form of sandhi voicing, to varying degrees across regional dialects.<ref name=":0">{{Cite book |last=Jenny |first=Mathias |title=Burmese: a comprehensive grammar |date=2016 |publisher=Routledge |others=San San Hnin Tun |isbn=978-1-315-65119-4 |series=Routledge comprehensive grammars |location=London New York}}</ref> Speakers from Yangon and [[Upper Myanmar]] exhibit more consistent use of sandhi voicing and assimilation than speakers from peripheral regions, though local and individual variation exists.<ref name=":0" /> In [[Rakhine language|Arakanese]] (Rakhine), voicing is limited to plain initials, while it is entirely absent in the [[Intha-Danu language|Intha dialect]].<ref name=":0" /> The following consonants are eligible for voicing in Burmese:
{| class="wikitable"
|+
!Original consonant
!1st stage of voicing
!2nd stage of voicing
|-
|{{IPA|/kʰ, k/}}
|{{IPA|/ɡ/}}
|{{IPA|/Ø/}}
|-
|{{IPA|/tɕʰ, tɕ/}}
|{{IPA|/dʑ/}} → {{IPA|/j/}}
|—
|-
|{{IPA|/sʰ, s/}}
|{{IPA|/z/}}
|—
|-
|{{IPA|/tʰ, t/}}
|{{IPA|/d/}}
|{{IPA|/ɾ/}}
|-
|{{IPA|/pʰ, p/}}
|{{IPA|/b/}} → {{IPA|/β/}} → {{IPA|/m/}}
|{{IPA|/Ø/}}
|-
|{{IPA|/θ/}}
|{{IPA|/ð/}}
|—
|-
|ŋ̊
|{{IPA|/ŋ/}}
|—
|-
|n̥
|{{IPA|/n/}}
|—
|-
|m̥
|{{IPA|/m/}}
|—
|-
|ɲ̥
|{{IPA|/ɲ̥/}}
|—
|}
Voicing generally occurs when a voicable consonant occurs between two vowels, and have voiced consonants. Some commonly used grammatical markers like {{Angbr|တယ်}} ({{Ipa|[tɛ]}} → {{Ipa|[dɛ]}} → {{Ipa|[ɾɛ]}}) and {{Angbr|ဘူး}} ({{Ipa|[bù]}} → {{Ipa|[ù]}}) also undergo the 2nd stage of voicing.<ref name=":0" /> Voicing also occurs in the pronunciation of [[Burmese numerals]] and classifiers.<ref name=":0" /> 

The primary type of sandhi voicing occurs when two syllables are joined to form a [[compound (linguistics)|compound word]], with the initial consonant of the second syllable becoming [[voiced consonant|voiced]].<ref name=":0" />

Examples:
:{{IPA|/sʰé/}} ({{lang|my|ဆေး}}) + {{IPA|/'''kʰ'''áɴ/}} ({{lang|my|ခန်း}}) > {{IPA|/sʰé '''ɡ'''áɴ/}} ("medicine" + "room" → "clinic")

The second type of consonant mutation occurs when the phoneme {{IPA|/dʑ/}} after the nasalized final {{IPA|/ɴ/}} becomes a {{IPA|/j/}} sound in compound words.

Examples:
:"blouse" ({{lang|my|အင်္ကျီ}} ''angkyi'') can be pronounced {{IPA|/èɪɴ'''dʑ'''í/}} or {{IPA|/èɪɴ'''j'''í/}}.

The third type of consonant mutation occurs when phonemes {{IPA|/p, pʰ, b, t, tʰ, d/}}, after the nasalized final {{IPA|/ɴ/}}, become {{IPA|/m/}} in compound words:

:{{IPA|/tàɪɴ/}} ({{lang|my|တိုင်}}) + {{IPA|/'''p'''ɪ̀ɴ/}} ({{lang|my|ပင်}}) > {{IPA|/tàɪɴ '''m'''ɪ̀ɴ/}} ({{lang|my|တိုင်ပင်}}) ("to consult")
:{{IPA|/táʊɴ/}} ({{lang|my|တောင်း}}) + {{IPA|/'''p'''àɴ/}} ({{lang|my|ပန်}}) > {{IPA|/táʊɴ '''m'''àɴ/}} ("to apologize")
:{{IPA|/lè jɪ̀ɴ/}} ({{lang|my|လေယာဉ်}}) + {{IPA|/'''p'''jàɴ/}} ({{lang|my|ပျံ}}) > {{IPA|/lèɪɴ '''m'''jàɴ/}} ("airplane")

=== Southern Oceanic languages ===
Mutation of the initial consonant of verbs is a feature of several languages in the [[Southern Oceanic languages|Southern Oceanic]] branch of the [[Austronesian language family]].

==== Central Vanuatu ====
Initial consonant mutation occurs in many [[Central Vanuatu languages]] like [[Raga language|Raga]]:

: ''nan '''v'''ano'' "I went"
: ''nam '''b'''ano'' "I go"

Those patterns of mutations probably arose when a nasal prefix, indicating the [[realis mood]], became combined with the verb's initial consonant.<ref>Crowley T, 1991. Parallel Development and Shared Innovation: Some Developments in Central Vanuatu Inflectional Morphology. ''Oceanic Linguistics'', Vol. 30, No. 2, pp. 179-222</ref> The possible ancestral pattern of mutation and its descendants in some modern Central Vanuatu languages are shown below:

{| class="wikitable"
!Proto-Central Vanuatu
!*k > *ŋk
!*r > *nr
!*p > *mp
|-
| Raga (Pentecost)
| x > ŋg
| t > d
| v / vw > b / bw
|-
| Northern Apma (Pentecost)
| k > ŋg
| t > d
| v / w > b / bw
|-
| Southern Apma (Pentecost)
|
|
| v / w > b / bw
|-
| Ske (Pentecost)
|
| z > d
| v / vw > b / bw
|-
| Lonwolwol (Ambrym)
|
| r > rV
| ∅ > bV
|-
| Southeast Ambrym
| x / h / ∅ > g
| t > d
| v / h > b
|-
| Northern Paama
| ∅ > k
| t > r
|
|-
| Central/Southern Paama
| k / ∅ > g / ŋ
| t / r > d
|
|-
| Nāti (Malekula)
| k / ʔ > ŋk
| t / r > nt / ntr
| v / w > mp / mpw
|-
| Maii (Epi)
|
| t > d
| v > b
|-
| Lewo (Epi)
|
|
| v / w > p / pw
|-
| Lamenu (Epi)
|
|
| ∅ > p
|-
| Bierebo (Epi)
| k > ŋk
| t / c > nd / nj
| v / w > p / pw
|-
| Baki (Epi)
|
| c > s
| v > mb
|-
| Bieria (Epi)
|
| t > nd
| v > mb
|-
| Nakanamanga (Efaté-Shepherds)
| k > ŋ
| r > t
| v / w > p / pw
|-
| Namakir (Shepherds)
| k > ŋ
| t / r > d
| v / w > b
|}

==== New Caledonia ====
Initial consonant mutation also serves a grammatical purpose in some [[New Caledonian languages]]. For example, [[Iaai language|Iaai]] uses initial consonant mutation in verbs to distinguish between specific/[[definite]] objects and generic/indefinite objects:

{| class="wikitable"
!Mutation
!Determinate object
!Indeterminate object
!Meaning
|-
| k > x
| kap
| xəp
| "welcome"
|-
| l > hl
| lele
| hlihli
| "pull, haul in"
|-
|n > hn
| nəŋ
| hnəŋ
| "brandish"
|-
| ɳ > hɳ
| ɳooc
| hɳuuk
| "tie"
|-
| t > θ
| təəʈ
| θəəʈ
| "lift up by the end"
|-
| w > hw
| wia
| hwiəə
| "turn, change"
|-
| v > hv
| vɛɖen
| hvɛɛʈ
| "carry on the shoulder"
|}

Those forms likely derive from an earlier [[reduplication]] of the first syllable in which the interconsonantal vowel was deleted, resulting in a [[Lenition#Spirantization|spirantization]] of the formerly reduplicated consonant.<ref>{{cite journal |last=Lynch |first=John |author-link=John Lynch (linguist) |date=2015 |title=The Phonological History of Iaai |url=https://c-cluster-110.uploads.documents.cimpress.io/v1/uploads/c77f9ffa-0e8a-4531-8460-b4b3483c3171~110/original?tenant=vbu-digital |journal=Journal of the Linguistic Society of Papua New Guinea |issn=0023-1959 |volume=33}}</ref>

=== Dholuo ===

The [[Dholuo language]] (one of the [[Luo languages]]) shows alternations between voiced and voiceless states of the final consonant of a noun stem.<ref>{{cite book |last=Stafford |first=R. |title=The Luo language |location=Nairobi |publisher=Longmans |year=1967}}</ref> In the [[construct state]] (the form that means 'hill of', 'stick of', etc.) the voicing of the final consonant is switched from the absolute state. (There are also often [[apophony|vowel alternations]] that are independent of consonant mutation.)
*{{IPA|ɡɔ'''t'''}} 'hill' (abs.), go'''d''' (const.)
*{{IPA|lʊ'''θ'''}} 'stick' (abs.), lu'''ð''' (const.)
*{{IPA|kɪ'''d'''o}} 'appearance' (abs.), ki'''t''' (const.)
*{{IPA|tʃo'''ɡ'''o}} 'bone' (abs.), {{IPA|tʃo'''k'''}} (const.)
*bu'''k''' 'book' (abs.), bu'''g''' (const.)
*{{IPA|kɪta'''b'''u}} 'book' (abs.), {{IPA|kɪta'''p'''}} (const.)

=== Fula ===

Consonant mutation is a prominent feature of the [[Fula language]]. The Gombe dialect spoken in [[Nigeria]], for example, shows mutation triggered by [[declension]] class.<ref>{{cite book|last=Arnott|first=D. W.|title=The Nominal and Verbal Systems of Fula|location=Oxford|publisher=Oxford University Press|year=1970}}</ref> The mutation grades are [[fortition]] and [[Prenasalized consonant|prenasalization]]:

{| class="wikitable" style="margin:1em auto;"
! Radical !! Fortition !! Prenasalization
|-
| f || p || p
|-
| s || {{IPA|ʃ}} || {{IPA|ʃ}}
|-
| h || k || k
|-
| w || b || mb
|-
| r || d || nd
|-
| j || {{IPA|dʒ}}, ɡ || {{IPA|ɲdʒ}}, {{IPA|ŋɡ}}
|-
| {{IPA|ɣ}} || ɡ || {{IPA|ŋɡ}}
|}

For example, the stems '''rim-''' 'free man' and '''{{IPA|[ɣim-]}}''' 'person' have the following forms:
*{{IPA|['''r'''imɓe]}} (class 2), '''d'''imo (class 1), '''nd'''imon (class 6)
*{{IPA|['''ɣ'''imɓe]}} (class 2), '''g'''imɗo (class 1), '''ŋg'''imkon (class 6)

=== Indonesian and Malay ===
The active form of a multisyllabic verb with an initial [[stop consonant]] or [[fricative consonant]] is formed by prefixing the verb stem with ''meN-'' in which ''N'' stands for a [[nasal consonant|nasal]] sharing the same [[place of articulation]] as the initial consonant:

*garuk → me'''ng'''garuk (= to scratch), hitung → me'''ng'''hitung (= to count),
*beri → me'''m'''beri (= to give), fitnah → me'''m'''fitnah (= to accuse falsely),
*cari → me'''n'''cari (= to search), dapat → me'''n'''dapat (= to obtain), *jangkau → me'''n'''jangkau (= to reach)

An initial consonant that is an unvoiced stop or ''s'' is deleted, leaving only the nasal in its place.

*'''k'''andung → me'''ng'''andung (= to contain or to be pregnant),
*'''p'''utih → me'''m'''utih (= to turn white),
*'''s'''atu → me'''ny'''atu (= to become one / to unite),
*'''t'''ulis → me'''n'''ulis (= to write).

Applied to verbs starting with a vowel, the nasal is realized as ''ng'' {{IPA|([ŋ])}}.

Monosyllabic verbs add an [[epenthetic vowel]] before prefixing and produce the prefix ''menge-'':

*bor (= boring tool / drill) → me'''nge'''bor (= to make a hole with drill).

Verbs starting with a nasal or [[approximant consonant]] do not add any mutant nasal, only ''me-''.<ref>Examples adapted from [[Wikibooks:Indonesian prefix me]]</ref>

The colloquial language (especially Jakartan Indonesian) drops ''me-'' prefix but tends to replace it with nasalization in some consonants:{{citation needed|date=December 2019}}

*'''t'''anya → '''men'''anya → '''n'''anya
*'''p'''ikir → '''mem'''ikir → '''m'''ikir
*'''me'''repotkan → '''ng(e)'''repotin

=== Latvian ===
More information is [[:lv:Līdzskaņu mija|available in the Latvian Wikipedia]].

{| class="wikitable"
|-
! Mutation !! Example
|-
| b→bj || gulbis→gulbja
|-
| c→č || lācis→lāča
|-
| d→ž || briedis→brieža
|-
| dz→dž || dadzis→dadža
|-
| g→dz || lūgt→lūdzu
|-
| k→c || liekt→liecu
|-
| l→ļ || sīlis→sīļa
|-
| m→mj || zeme→zemju
|-
| n→ņ || zirnis→zirņa
|-
| p→pj || krupis→krupja
|-
| r→r || teteris→tetera
|-
| s→š || lasis→laša
|-
| t→š || vācietis→vācieša
|-
| v→vj || cirvis→cirvja
|-
| z→ž || vēzis→vēža
|}

Also two consonants can mutate as a group.

{| class="wikitable"
|-
! Mutation !! Example
|-
| kst→kš || pāksts→pākšu
|-
| ln→ļņ || cilnis→ciļņa
|-
| sl→šļ || kāpslis→kāpšļa
|-
| sn→šņ || atkusnis→atkušņa
|-
| zl→žļ || zizlis→zižļa
|-
| zn→žņ || zvaigzne→zvaigžņu
|}

=== Ute ===
In [[Ute dialect|Ute]], also called Southern Paiute, there are three consonant mutations, which are triggered by different word-stems,<ref>{{cite journal |author-link=Edward Sapir |last=Sapir |first=Edward |title=The Southern Paiute Language (Part I): Southern Paiute, a Shoshonean Language |journal=Proceedings of the American Academy of Arts and Sciences |volume=65 |issue=1 |year=1930 |pages=1–296 |doi=10.2307/20026309|jstor=20026309 }}</ref> The mutations are [[spirantization]], [[gemination]], and [[prenasalized consonant|prenasalization]]:

{| class="wikitable" style="margin:1em auto;"
! Radical !! Spirantization !! Gemination !! Prenasalization
|-
| p || v || pp || mp
|-
| t || r || tt || nt
|-
| k || {{IPA|ɣ}} || kk || {{IPA|ŋk}}
|-
| {{IPA|kʷ}} || {{IPA|ɣʷ}} || {{IPA|kkʷ}}|| {{IPA|ŋkʷ}}
|-
| ts || &nbsp; || tts || nts
|-
| s || &nbsp; || ss || &nbsp;
|-
| m || {{IPA|ŋkʷ}}|| mm || mm
|-
| n || &nbsp; || nn || nn
|}

For example, the absolutive suffix '''-pi''' appears in different forms, according to the noun stem to which it is suffixed:
*movi-'''ppi''' 'nose'
*sappI-'''vi''' 'belly'
*{{IPA|aŋo}}-'''mpi''' 'tongue'

== See also ==
* [[Lenition]]
* [[Fortition]]
* [[Consonant gradation]]
* [[Rendaku]]
* [[Sonority hierarchy]]
* [[Apophony]]
* [[Elision]]
* [[Historical linguistics]]

== References ==
{{reflist}}

== Further reading ==
*Grijzenhout, Janet. 2011. 'Consonant Mutation' in Marc van Oostendorp, Colin J. Ewen, Elizabeth Hume and Keren Rice (eds.) ''The Blackwell Companion to Phonology'' (Oxford: Blackwell) III: 1537-1558.
*Zimmer, Stefan. [https://www.academia.edu/4113963/2005_The_Celtic_Mutations_some_typological_comparisons The Celtic Mutations: some typological comparisons]. A Companion in Linguistics, a Festschrift for Anders Ahlqvist, ed. B. Smelik, R. Hofman, C. Hamans, D. Cram. Nijmegen: de Keltische Draak / Münster: Nodus 2004, 127-140.

[[Category:Celtic languages]]
[[Category:Linguistic morphology]]
[[Category:Phonology]]
[[Category:Syntax]]