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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 has three degrees of labialization: tight rounded (/w/, initial /r/), slight rounded (/ʃ/, /ʒ/, /tʃ/, /dʒ/, coloring /r/), and unrounded, which in vowels is sometimes called 'spread'. These secondary articulations are not universal.[ example needed ]

A few languages, including Arrernte and Mba, have contrastive labialized forms for almost all of their consonants.



Out of 706 language inventories surveyed by Ruhlen (1976), 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 [ʷ] (Unicode U+02B7), as in /kʷ/. (Elsewhere this diacritic generally indicates simultaneous labialization and velarization.[ citation needed ]) There are also diacritics, respectively [ɔ̹], [ɔ̜], to indicate greater or lesser degrees of rounding. [3] 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 /x/, /x̹/, /xʷ/ or /x/, /x̜ʷ/, /xʷ/.

The extensions to the IPA has two additional symbols for degrees of rounding: Spread [ɹ͍] and open-rounded [ʒꟹ] (as in English). It also has a symbol for labiodentalized sounds, [tᶹ]. [4]

If precision is desired, the Abkhaz and Ubykh articulations may be transcribed with the appropriate fricative or trill raised as a diacritic: [tᵛ], [tᵝ], [tʙ], [tᵖ].

For simple labialization, Ladefoged & Maddieson (1996) resurrected an old IPA symbol, [ ̫], [5] which would be placed above a letter with a descender such as ɡ. However, their chief example is Shona sv and zv, which they transcribe /s̫/ and /z̫/ but which actually seem to be whistled sibilants, without necessarily being labialized. [6] Another possibility is to use the IPA diacritic for rounding, distinguishing for example the labialization in English soon[s̹] and [sʷ]swoon. [7] The open rounding of English /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, /k/ may become /kʷ/ in the environment of /o/, or /a/ may become /o/ in the environment of /p/ or /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.





Sibilant affricates

Non-sibilant affricates

Lateral affricates


Sibilant fricatives

Central non-sibilant fricatives


Lateral fricatives




See also

Related Research Articles

Click consonants, or clicks, are speech sounds that occur as consonants in many languages of Southern Africa and in three languages of East Africa. Examples familiar to English-speakers are the Tut-tut or Tsk! Tsk! used to express disapproval or pity, the tchick! used to spur on a horse, and the clip-clop! sound children make with their tongue to imitate a horse trotting.

Fricatives are consonants produced by forcing air through a narrow channel made by placing two articulators close together. These may be the lower lip against the upper teeth, in the case of ; the back of the tongue against the soft palate, in the case of German ; or the side of the tongue against the molars, in the case of Welsh. This turbulent airflow is called frication.

A lateral is a consonant in which the airstream proceeds along the sides of the tongue, but it is blocked by the tongue from going through the middle of the mouth. An example of a lateral consonant is the English L, as in Larry.

An affricate is a consonant that begins as a stop and releases as a fricative, generally with the same place of articulation. It is often difficult to decide if a stop and fricative form a single phoneme or a consonant pair. English has two affricate phonemes, and, often spelled ch and j, respectively.

Uvulars are consonants articulated with the back of the tongue against or near the uvula, that is, further back in the mouth than velar consonants. Uvulars may be stops, fricatives, nasals, trills, or approximants, though the IPA does not provide a separate symbol for the approximant, and the symbol for the voiced fricative is used instead. Uvular affricates can certainly be made but are rare: they occur in some southern High-German dialects, as well as in a few African and Native American languages. Uvular consonants are typically incompatible with advanced tongue root, and they often cause retraction of neighboring vowels.

In phonetics, sibilants are fricative consonants of higher amplitude and pitch, made by directing a stream of air with the tongue towards the teeth. Examples of sibilants are the consonants at the beginning of the English words sip, zip, ship, and genre. The symbols in the International Phonetic Alphabet used to denote the sibilant sounds in these words are, respectively,. Sibilants have a characteristically intense sound, which accounts for their paralinguistic use in getting one's attention.

Ubykh, an extinct Northwest Caucasian language, has the largest consonant inventory of all documented languages that do not use clicks, and also has the most disproportional ratio of phonemic consonants to vowels. It has consonants in at least eight, perhaps nine, basic places of articulation and 29 distinct fricatives, 27 sibilants, and 20 uvulars, more than any other documented language. Some Khoisan languages, such as ǃXóõ, may have larger consonant inventories due to their extensive use of click consonants, although some analyses view a large proportion of the clicks in these languages as clusters, which would bring them closer into line with the Caucasian languages.

Pharyngealization Secondary articulation of consonants or vowels where the pharynx or epiglottis is constricted during articulation

Pharyngealization is a secondary articulation of consonants or vowels by which the pharynx or epiglottis is constricted during the articulation of the sound.

In phonetics, ejective consonants are usually voiceless consonants that are pronounced with a glottalic egressive airstream. In the phonology of a particular language, ejectives may contrast with aspirated, voiced and tenuis consonants. Some languages have glottalized sonorants with creaky voice that pattern with ejectives phonologically, and other languages have ejectives that pattern with implosives, which has led to phonologists positing a phonological class of glottalic consonants, which includes ejectives.

The uvular ejective is a type of consonantal sound, used in some spoken languages. The symbol in the International Phonetic Alphabet that represents this sound is ⟨⟩.

Kabardian language Northwest Caucasian language

Kabardian also known as East Circassian, is a Northwest Caucasian language closely related to the Adyghe language. Circassian nationalists reject the distinction between the two languages and refer to them both as "Circassian".

Implosive consonants are a group of stop consonants with a mixed glottalic ingressive and pulmonic egressive airstream mechanism. That is, the airstream is controlled by moving the glottis downward in addition to expelling air from the lungs. Therefore, unlike the purely glottalic ejective consonants, implosives can be modified by phonation. Contrastive implosives are found in approximately 13% of the world's languages.

Doubly articulated consonants are consonants with two simultaneous primary places of articulation of the same manner. They are a subset of co-articulated consonants. They are to be distinguished from co-articulated consonants with secondary articulation; that is, a second articulation not of the same manner. An example of a doubly articulated consonant is the voiceless labial-velar plosive, which is a and a pronounced simultaneously. On the other hand, the voiceless labialized velar plosive has only a single stop articulation, velar, with a simultaneous approximant-like rounding of the lips. In some dialects of Arabic, the voiceless velar fricative has a simultaneous uvular trill, but this is not considered double articulation either.

Abkhaz is a language of the Northwest Caucasian family which, like the other Northwest Caucasian languages, is very rich in consonants. Abkhaz has a large consonantal inventory that contrasts 58 consonants in the literary Abzhywa dialect, coupled with just two phonemic vowels.

The voiceless velar lateral affricate is an uncommon speech sound found as a phoneme in the Caucasus and as an allophone in several languages of eastern and southern Africa.

Pulmonic-contour clicks, also called sequential linguo-pulmonic consonants, are consonants that transition from a click to an ordinary pulmonic sound, or more precisely, have an audible delay between the front and rear release of the click. All click types have linguo-pulmonic variants, which occur as both stops and affricates, and are attested in four phonations: tenuis, voiced, aspirated, and murmured. At least a voiceless linguo-pulmonic affricate is attested from all Khoisan languages of southern Africa, as well as (reportedly) from the Bantu language Yeyi from the same area, but they are unattested elsewhere.

Adyghe is a language of the Northwest Caucasian family which, like the other Northwest Caucasian languages, is very rich in consonants, featuring many labialized and ejective consonants. Adyghe is phonologically more complex than Kabardian, having the retroflex consonants and their labialized forms.


  1. As a mnemonic, the more-rounded diacritics resembles the rounded vowel ɔ.
  2. International Phonetic Association (1999). Handbook of the International Phonetic Association: A Guide to the Use of the International Phonetic Alphabet. Cambridge University Press. p. 190. ISBN   978-0-52163751-0.
  3. This is not a subscript w but originally a subscript omega that "recalls the letter w" (Jespersen & Pedersen, 1926, Phonetic Transcription and Transliteration: Proposals of the Copenhagen Conference, April 1925. Oxford University Press).
  4. See . Archived May 16, 2008, at the Wayback Machine
  5. John Esling (2010) "Phonetic Notation", in Hardcastle, Laver & Gibbon (eds) The Handbook of Phonetic Sciences, 2nd ed.
  6. Yanushevskaya & Bunčić (2015 :223)