Labialization is a secondary articulatory feature of sounds in some languages. Labialized sounds involve the lips while the remainder of the oral cavity produces another sound. The term is normally restricted to consonants. When vowels involve the lips, they are called rounded.
The most common labialized consonants are labialized velars. Most other labialized sounds also have simultaneous velarization, and the process may then be more precisely called labio-velarization.
In phonology, labialization may also refer to a type of assimilation process.
Labialization is the most widespread secondary articulation in the world's languages. It is phonemically contrastive in Northwest Caucasian (e.g. Adyghe), Athabaskan, and Salishan language families, among others. This contrast is reconstructed also for Proto-Indo-European, the common ancestor of the Indo-European languages; and it survives in Latin and some Romance languages. It is also found in the Cushitic and Ethio-Semitic languages.
American English labializes pronounced as //r, ʃ, ʒ, tʃ, dʒ// to various degrees.
A few languages, including Arrernte and Mba, have contrastive labialized forms for almost all of their consonants.
Out of 706 language inventories surveyed by, labialization occurred most often with velar (42%) and uvular (15%) segments and least often with dental and alveolar segments. With non-dorsal consonants, labialization may include velarization as well. Labialization is not restricted to lip-rounding. The following articulations have either been described as labialization, or been found as allophonic realizations of prototypical labialization:
Eastern Arrernte has labialization at all places and manners of articulation; this derives historically from adjacent rounded vowels, as is also the case of the Northwest Caucasian languages. Marshallese also has phonemic labialization as a secondary articulation at all places of articulation except for labial consonants and coronal obstruents.
In North America, languages from a number of families have sounds that sound labialized (and vowels that sound rounded) without participation of the lips. See Tillamook language for an example.
In the International Phonetic Alphabet, labialization of velar consonants is indicated with a raised w modifier pronounced as /[ʷ]/ (Unicode U+02B7), as in pronounced as //kʷ//. (Elsewhere this diacritic generally indicates simultaneous labialization and velarization.) There are also diacritics, respectively pronounced as /[ɔ̹], [ɔ̜]/, to indicate greater or lesser degrees of rounding. These are normally used with vowels, but may occur with consonants. For example, in the Athabaskan language Hupa, voiceless velar fricatives distinguish three degrees of labialization, transcribed either pronounced as //x/, /x̹/, /xʷ// or pronounced as //x/, /x̜ʷ/, /xʷ//.
The extensions to the IPA has two additional symbols for degrees of rounding: Spread pronounced as /[ɹ͍]/ and open-rounded pronounced as /[ʒꟹ]/ (as in English). It also has a symbol for labiodentalized sounds, pronounced as /[tᶹ]/.
If precision is desired, the Abkhaz and Ubykh articulations may be transcribed with the appropriate fricative or trill raised as a diacritic: pronounced as /[tᵛ]/, pronounced as /[tᵝ]/, pronounced as /[t<sup>ʙ</sup>]/, pronounced as /[tᵖ]/.
For simple labialization, resurrected an old IPA symbol, pronounced as /[ ̫]/, which would be placed above a letter with a descender such as pronounced as /ɡ/. However, their chief example is Shona sv and zv, which they transcribe pronounced as //s̫// and pronounced as //z̫// but which actually seem to be whistled sibilants, without necessarily being labialized. Another possibility is to use the IPA diacritic for rounding, distinguishing for example the labialization in English soon pronounced as /[s̹]/ and pronounced as /[sʷ]/ swoon. The open rounding of English pronounced as //ʃ// is also unvelarized.
Labialization also refers to a specific type of assimilatory process where a given sound become labialized due to the influence of neighboring labial sounds. For example, pronounced as //k// may become pronounced as //kʷ// in the environment of pronounced as //o//, or pronounced as //a// may become pronounced as //o// in the environment of pronounced as //p// or pronounced as //kʷ//.
In the Northwest Caucasian languages as well as some Australian languages rounding has shifted from the vowels to the consonants, producing a wide range of labialized consonants and leaving in some cases only two phonemic vowels. This appears to have been the case in Ubykh and Eastern Arrernte, for example. The labial vowel sounds usually still remain, but only as allophones next to the now-labial consonant sounds.
|Stops||plain||labzd voiceless bilabial stop||Chaha, Paha|
|labzd voiced bilabial stop|
|labzd voiceless alveolar stop||Archi, Abkhaz, Lao, Paha, Ubykh|
|labzd voiced alveolar stop||Archi, Abkhaz, Ubykh|
|labzd voiceless velar stop||Abaza, Abkhaz, Adyghe, Halkomelem, Kabardian, Taos, Chipewyan, Hadza, Gwichʼin, Tlingit, Akan, Nez Perce, Archi, Cantonese, Wariʼ, Chaha, Dahalo, Hausa, Igala, Igbo, Italian, Lao, Latin, Nahuatl, Nawat, Ossetic, Paha, Portuguese, Thai, Tigrinya, Hiw, Ubykh, Bearlake Slavey, Breton|
|labzd voiced velar stop||Abaza, Abkhaz, Adyghe, Akan, Archi, Chaha, Dahalo, Hausa, Oowekyala, Ossetic, Hadza, Igala, Igbo, Gwichʼin, Kabardian, Paha, Portuguese, Tigrinya, Ubykh, Breton, Yoruba|
|labzd voiceless uvular stop||Abaza, Abkhaz, Adyghe, Kabardian, Ossetic, Paha, Tlingit, Nez Perce, Ubykh|
|labzd pharyngealized voiceless uvular stop||pronounced as /[qˤʷ]/||Archi, Ubykh|
|labzd voiced uvular stop||Oowekyala, Kwak'wala, Tsakhur|
|labzd glottal stop||Adyghe, Kabardian, Lao, Tlingit|
|labzd prenasalized voiced bilabial plosive||pronounced as /[ᵐbʷ]/||Tamambo|
|Labial–velar||labzd voiceless labio–velar stop||pronounced as /[k͡pʷ]/||Dorig, Mwotlap|
|labzd prenasalized voiced labial–velar stop||pronounced as /[ᵑɡ͡bʷ]/||Volow|
|Affricates||sibilant||labzd voiceless alveolar affricate||Adyghe, Archi, Lezgian, Tsakhur|
|labzd voiced alveolar affricate||Adyghe, Dahalo|
|labzd voiceless palato-alveolar affricate||Archi, Abaza, Adyghe, Paha, Aghul, German|
|labzd voiced palato-alveolar affricate||Abaza, Aghul, Tsakhur, German|
|labzd voiceless alveolo-palatal affricate||pronounced as /[t͡ɕʷ]/||Abkhaz, Akan, Ubykh|
|labzd voiced alveolo-palatal affricate||pronounced as /[d͡ʑʷ]/||Abkhaz, Akan, Ubykh|
|non-sibilant||labzd voiceless velar affricate||Navajo|
|labzd voiceless uvular affricate||Kabardian, Lillooet|
|lateral||labzd voiceless velar lateral affricate||Archi|
|Fricatives||sibilant||labzd voiceless alveolar sibilant||Archi, Lao, Lezgian|
|labzd voiced alveolar sibilant||Archi, Tsakhur, Lezgian|
|labzd voiceless palato-alveolar sibilant||Archi, Abaza, Abkhaz, Adyghe, Paha, Aghul, Ubykh|
|labzd voiced palato-alveolar sibilant||Archi, Abaza, Abkhaz, Adyghe, Aghul, Ubykh|
|labzd voiceless retroflex sibilant||Bzhedug|
|labzd voiced retroflex sibilant||Bzhedug|
|labzd voiceless alveolo-palatal sibilant||Abkhaz, Ubykh|
|labzd voiced alveolo-palatal sibilant||Abkhaz, Ubykh|
|non-sibilant||labzd voiceless bilabial fricative||pronounced as /[ɸʷ]/|
|labzd voiced bilabial fricative||pronounced as /[βʷ]/||Tamambo|
|labzd voiceless labiodental fricative||Hadza, Chaha|
|labzd voiced labiodental fricative|
|labzd voiceless dental fricative||Paha|
|labzd voiced dental fricative||Paha|
|labzd voiceless palatal fricative||Akan|
|labzd voiceless velar fricative||Abaza, Adyghe, Avestan, Chaha, Halkomelem, Kabardian, Oowekyala, Taos, Navajo, Tigrinya, Lillooet, Tlingit|
|labzd voiced velar fricative||Abaza, Navajo, Lillooet, Gwichʼin, possibly Proto-Indo-European|
|labzd voiceless uvular fricative||Abkhaz, Adyghe, Archi, Halkomelem, Kabardian, Lillooet, Tlingit, Wariʼ, Chipewyan, Oowekyala, Ossetic, Ubykh|
|labzd pharyngealized voiceless uvular fricative||pronounced as /[χˤʷ]/||Abkhaz, Archi, Ubykh|
|labzd voiced uvular fricative||Abkhaz, Adyghe, Chipewyan, Kabardian, Ubykh|
|labzd pharyngealized voiced uvular fricative||pronounced as /[ʁˤʷ]/||Archi, Ubykh|
|labzd voiceless pharyngeal fricative||Abaza, Abkhaz|
|labzd voiced pharyngeal fricative||Abaza, Lillooet|
|Pseudo-fricatives||labzd voiceless glottal fricative||Akan, Tlingit, Tsakhur|
|Lateral fricatives||labzd voiceless alveolar lateral fricative||Dahalo|
|labzd voiceless velar lateral fricative||Archi|
|Nasals||labzd bilabial nasal||Chaha, Paha, Tamambo|
|labzd palatal nasal||pronounced as /[ɲʷ]/||Akan|
|labzd velar nasal||pronounced as /[ŋʷ]/||Akan, Avestan, Lao, Hiw, Igala|
|labzd labial-velar nasal||pronounced as /[ŋ͡mʷ]/||Dorig, Mwotlap|
|Approximants||labzd alveolar lateral approximant||Lao|
|labzd labiodental approximant||pronounced as /[ʋʷ]/||Russian|
|labialized palatal approximant||pronounced as /[ɥ]/||Abkhaz, Akan, French, Mandarin, Paha|
|Labio-velar approximant (voiced)||pronounced as /[w]/||widespread; in every above-mentioned language, as well as e.g. Arabic, English, Korean, Vietnamese|
|Voiceless labio-velar approximant||pronounced as /[ʍ]/||certain dialects of English|
|nasal labialized velar approximant||pronounced as /[w̃]/|
|labzd postalveolar approximant||pronounced as /[ɹ̠ʷ]/||many dialects of English|
|Ejectives||labzd bilabial ejective||Adyghe|
|labzd alveolar ejective||Abkhaz, Adyghe, Ubykh|
|labzd velar ejective||Abaza, Abkhaz, Adyghe, Archi, Bearlake Slavey, Chipewyan, Halkomelem, Kabardian, Ossetic, Tlingit, Ubykh|
|labzd palato-alveolar ejective fricative||Adyghe|
|labzd uvular ejective||Abaza, Abkhaz, Archi, Halkomelem, Hakuchi, Tlingit, Ubykh|
|labzd pharyngealized uvular ejective||pronounced as /[qˤʷʼ]/||Archi, Ubykh|
|labzd alveolar ejective affricate||pronounced as /[t͡sʷʼ]/||Archi, Khwarshi|
|labzd alveolar lateral ejective affricate||pronounced as /[t͡ɬʷʼ]/||Khwarshi|
|labzd palato-alveolar ejective affricate||pronounced as /[t͡ʃʷʼ]/||Abaza, Archi, Khwarshi|
|labzd alveolo-palatal ejective affricate||pronounced as /[t͡ɕʷʼ]/||Abkhaz, Ubykh|
|labzd retroflex ejective affricate||pronounced as /[ʈ͡ʂʷʼ]/||allophonic in Adyghe|
|labzd velar lateral ejective affricate||pronounced as /[k͡ʟ̝̊ʷʼ]/||Archi|
|labzd velar ejective fricative||pronounced as /[xʷʼ]/||Tlingit|
|labzd uvular ejective fricative||pronounced as /[χʷʼ]/||Tlingit|
pronounced as /navigation/