View source for Click consonant

{{Short description|Speech sounds in several African languages}}
{{More citations needed|article|date=March 2025}}
{{Use dmy dates|date=June 2020}}
<!--audio should not be enabled until we have passable recordings for the clicks. The [ǂ] is completely wrong as of June 2021, but the others aren't plain clicks either. The table has no other purpose. {{IPA non-pulmonic consonants |ejectives=no|implosives=no|audio=no|class=floatright}}-->
{{Infobox symbol
|mark = {{IPA|ʘ ǀ ǁ ǂ ǃ 𝼊}}
|name=Click releases
|unicode=
{{unichar|0298|Latin letter bilabial click}}<br  />
{{unichar|01C0|Latin letter dental click}}<br />
{{unichar|01C1|Latin letter lateral click}}<br  />
{{unichar|01C2|Latin letter alveolar click}}<br  />
{{unichar|01C3|Latin letter retroflex click}}<br  />
{{unichar|01DF0A|Latin letter retroflex click with retroflex hook}}
|different from=
{{unichar|007C|Vertical line| nlink=Vertical bar}}<br />
{{unichar|2016|Double vertical line|nlink=Vertical bar}}<br />{{unichar|0021|Exclamation mark|nlink=Exclamation mark}}<br />{{unichar|2021|Double dagger|nlink=Double dagger}}
{{unichar|A668|Cyrillic capital letter monocular o|nlink=Cyrillic o variants}}
}}
{{Contains special characters
| special    = uncommon [[Unicode]] characters
| fix        = Help:Multilingual support
| error      = [[Specials (Unicode block)#Replacement character|question marks, boxes, or other symbols]]
| characters = the intended characters
| image      = Replacement character.svg
| link       = Specials (Unicode block)#Replacement character
| alt        = <?>
| compact    = 
}}
'''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 language|English-speakers]] are the ''[[tut-tut]]'' (British spelling) or ''[[Dental click|tsk! tsk!]]'' (American spelling) used to express disapproval or pity (IPA {{IPA|[ǀ]}}), the ''[[lateral click|tchick!]]'' used to spur on a horse (IPA {{IPA|[ǁ]}}), and the ''[[alveolar click|clip-clop!]]'' sound children make with their tongue to imitate a horse trotting (IPA {{IPA|[ǃ]}}). However, these [[paralinguistic]] sounds in English are not full click consonants, as they only involve the front of the tongue, without the release of the back of the tongue that is required for clicks to combine with vowels and form syllables.

Anatomically, clicks are [[obstruent]]s articulated with two closures (points of contact) in the mouth, one forward and one at the back. The enclosed pocket of air is [[rarefaction|rarefied]] by a sucking action of the tongue (in technical terminology, clicks have a [[Airstream mechanism|lingual ingressive airstream mechanism]]). The forward closure is then released,<ref group=note>This is the case for all clicks used as consonants in words. Paralinguistically, however, there are other methods of making clicks: ''under'' the tongue or as above but by releasing the rear occlusion first. See [[#Places of articulation]].</ref> producing what may be the loudest consonants in the language, although in some languages such as [[Hadza language|Hadza]] and [[Sandawe language|Sandawe]], clicks can be more subtle and may even be mistaken for [[ejective consonant|ejectives]].

==Phonetics and IPA notation==
Click consonants occur at six principal places of articulation. The [[International Phonetic Alphabet (IPA)]] provides five letters for these places (there is as yet no dedicated symbol for the sixth). 
* The easiest clicks for English speakers are the [[dental click]]s written with {{angbr IPA|ǀ}}. These are sharp (high-pitched) squeaky sounds made by sucking on the front teeth. A simple dental click is used in English to express pity or to shame someone, or to call a cat or other animal, and is written ''tut!'' in British English and ''tsk!'' in American English. In many cultures around the Mediterranean a simple dental click is used for "no" in answer to a direct question. They are written with the letter ''c'' in [[Zulu language|Zulu]] and [[Xhosa language|Xhosa]]. 
* Next most familiar to English speakers are the [[lateral click]]s, which are written with {{angbr IPA|ǁ}}. They are also squeaky sounds, though less sharp than {{IPA|[ǀ]}}, made by sucking on the molars on either side (or both sides) of the mouth. A simple lateral click is made in English to get a horse moving, and is conventionally written ''tchick!''. They are written with the letter ''x'' in Zulu and Xhosa. 
* Then there are the [[bilabial click]]s, written with {{angbr IPA|ʘ}}. These are lip-smacking sounds, but often without the pursing of the lips found in a kiss,  that occur in words in only a few languages.

The above clicks sound like [[affricate]]s, in that they involve a lot of friction. The next two families of clicks are more abrupt sounds that do not have this friction.
* With the [[alveolar click]]s, written with {{angbr IPA|ǃ}}, the tip of the tongue is pulled down abruptly and forcefully from the roof of the mouth, sometimes using a lot of jaw motion, and making a hollow ''pop!'' like a cork being pulled from an empty bottle. Something like these sounds may be used for a 'clip-clop' sound as noted above. These sounds can be quite loud. They are written with the letter ''q'' in Zulu and Xhosa. 
* The [[palatal click]]s, {{angbr IPA|ǂ}}, are made with a flat tongue that is pulled backward rather than downward, and are sharper cracking sounds than the {{IPA|[ǃ]}} clicks, like sharply snapped fingers. They are not found in Zulu but are very common in the San languages of southern Africa. 
* Finally, the [[retroflex click]]s are poorly known, being attested from only a single language, [[Central !Kung]]. The tongue is curled back in the mouth, and they are both fricative and hollow sounding, but descriptions of these sounds vary between sources. This may reflect dialect differences. They are perhaps most commonly written {{angbr IPA|‼}}, but that is an ''ad hoc'' transcription. The expected IPA letter is {{angbr IPA|𝼊}} ({{angbr IPA|ǃ}} with retroflex tail), and the IPA supported the addition of that letter to Unicode.
Technically, these IPA letters transcribe only the forward articulation of the click, not the entire consonant. As the ''Handbook'' states,<ref>IPA ''Handbook'', p. 10</ref> 
{{blockquote|Since any click involves a velar or uvular closure [as well], it is possible to symbolize factors such as voicelessness, voicing or nasality of the click by combining the click symbol with the appropriate velar or uvular symbol: {{IPA|[k͡ǂ ɡ͡ǂ ŋ͡ǂ]}}, {{IPA|[q͡ǃ]}}.<ref>Instead of a tie bar, a superscript velar or uvular letter is sometimes seen: {{angbr IPA|ᵏǂ ᶢǂ ᵑǂ 𐞥ǂ}} etc.</ref>}}
Thus technically {{IPA|[ǂ]}} is not a consonant, but only one part of the articulation of a consonant, and one may speak of "ǂ-clicks" to mean any of the various click consonants that share the {{IPA|[ǂ]}} place of articulation.<ref>This can be convenient, as different authorities call the ǂ-clicks different things, so while it is unambiguous to call them "ǂ-clicks", it can be confusing to refer to them with terms like 'palatal', 'palato-alveolar' or 'alveolar', all of which have been used for both the sharp, flat-sounding ǂ-clicks and for the hollow-sounding ǃ-clicks.</ref> In practice, however, the simple letter {{angbr IPA|ǂ}} has long been used as an abbreviation for {{IPA|[k͡ǂ]}}, and in that role it is sometimes seen combined with diacritics for voicing (e.g. {{angbr IPA|ǂ̬}} for {{IPA|[ɡ͡ǂ]}}), nasalization (e.g. {{angbr IPA|ǂ̃}} for {{IPA|[ŋ͡ǂ]}}), etc. These differing transcription conventions may reflect differing theoretical analyses of the nature of click consonants, or attempts to address common misunderstandings of clicks.

==Languages with clicks==

=== Southern Africa ===
Clicks occur in all three [[Khoisan languages|Khoisan language families]] of [[southern Africa]], where they may be the most numerous consonants. To a lesser extent they occur in three neighbouring groups of [[Bantu languages]]—which [[Sprachbund|borrowed them]], directly or indirectly, from Khoisan. In the southeast, in eastern [[South Africa]], [[Eswatini]], [[Lesotho]], [[Zimbabwe]] and southern [[Mozambique]], they were adopted from a [[Tuu languages|Tuu language]] (or languages) by the languages of the Nguni cluster (especially [[Zulu language|Zulu]], [[Xhosa language|Xhosa]] and [[Phuthi language|Phuthi]], but also to a lesser extent [[Swati language|Swazi]] and [[Southern Ndebele language|Ndebele]]), and spread from them in a reduced fashion to the Zulu-based [[pidgin]] [[Fanagalo]], [[Sesotho language|Sesotho]], [[Tsonga language|Tsonga]], [[Ronga language|Ronga]], the Mzimba dialect of [[Tumbuka language|Tumbuka]] and more recently to [[Ndau language|Ndau]] and urban varieties of [[Pedi language|Pedi]], where the spread of clicks continues. The second point of transfer was near the [[Caprivi Strip]] and the [[Okavango River]] where, apparently, the [[Yeyi language]] borrowed the clicks from a [[Khoe languages|West Kalahari Khoe language]]; a separate development led to a smaller click inventory in the neighbouring [[Mbukushu language|Mbukushu]], [[Kwangali language|Kwangali]], [[Gciriku language|Gciriku]], [[Kuhane language|Kuhane]] and [[Fwe language|Fwe]] languages in [[Angola]], [[Namibia]], [[Botswana]] and [[Zambia]].<ref>{{cite book |first=Derek |last=Nurse |first2=Gérard |last2=Philippson |year=2003 |title=The Bantu languages |pages=31–32 }}</ref> These sounds occur not only in borrowed vocabulary, but have spread to native Bantu words as well, in the case of Nguni at least partially due to a type of word taboo called [[hlonipha]]. Some [[creolised]] varieties of Afrikaans, such as [[Oorlams Creole|Oorlams]], retain clicks in [[Khoekhoe language|Khoekhoe]] words.

=== East Africa ===
Three languages in [[East Africa]] use clicks: [[Sandawe language|Sandawe]] and [[Hadza language|Hadza]] of [[Tanzania]], and [[Dahalo language|Dahalo]], an endangered South [[Cushitic languages|Cushitic language]] of [[Kenya]] that has clicks in only a few dozen words. It is thought the latter may remain from an episode of [[language shift]].

=== Damin ===
The only non-African language known to have clicks as regular speech sounds is [[Damin]], a ritual code once used by speakers of [[Lardil language|Lardil]] in [[Australia]]. In addition, one consonant in Damin is the [[Egressive sound|egressive]] equivalent of a click, using the tongue to compress the air in the mouth for an outward (egressive) "spurt".<ref>{{cite web | url=https://www.britannica.com/topic/click-languages | title=Click languages &#124; Britannica }}</ref><ref>{{Cite book |last1=Hale |first1=Ken |last2=Nash |first2=David |chapter=Damin and Lardil Phonotactics |title=Boundary Rider: Essays in Honour of Geoffrey O'Grady |editor-first=Darrell |editor-last=Tryon |editor2-first=Michael |editor2-last=Walsh |pages=247–259 |location=Canberra |publisher=Pacific Linguistics, ANU |year=1997 |chapter-url=https://openresearch-repository.anu.edu.au/bitstream/1885/253893/1/PL-C136.247.pdf}}</ref>

== Use ==

===Spread of clicks from loanwords===
Once clicks are borrowed into a language as regular speech sounds, they may spread to native words, as has happened due to ''[[hlonipa]]'' word-taboo in the [[Nguni languages]]. In [[Gciriku language|Gciriku]], for example, the European loanword ''tomate'' (tomato) appears as ''cumáte'' with a click {{IPA|[ǀ]}}, though it begins with a ''t'' in all neighbouring languages. It has also been argued that click phonemes have been adopted into some languages through the process of [[Avoidance speech|''hlonipha'']], women refraining from saying certain words and sounds that were similar to the name of their husband, sometimes replacing local sounds by borrowing clicks from a nearby language.<ref>{{cite journal |last=Gunnink |first=Hilde |title=The adoption and proliferation of clicks in Bantu languages: the role of ''hlonipha'' revisited |journal=South African Journal of African Languages |volume=43 |issue=3 |year=2023 |pages=216–225 |doi=10.1080/02572117.2023.2294412 }}</ref>

=== Marginal usage of clicks ===
Scattered clicks are found in [[ideophone]]s and mimesis in other languages, such as [[Kongo language|Kongo]] {{IPA|/ᵑǃ/}}, [[Mijikenda language|Mijikenda]] {{IPA|/ᵑǀ/}} and Hadza {{IPA|/ᵑʘʷ/}} (Hadza does not otherwise have labial clicks). Ideophones often use phonemic distinctions not found in normal vocabulary.

English and many other languages may use bare click releases in [[interjection]]s, without an accompanying rear release or transition into a vowel, such as the dental "tsk-tsk" sound used to express disapproval, or the lateral ''tchick'' used with horses. In a number of languages ranging from the central Mediterranean to Iran,<ref>Including [[Armenian language|Armenian]], [[Bulgarian language|Bulgarian]], [[Greek language|Greek]], [[Levantine Arabic]], [[Maltese language|Maltese]], [[Persian language|Persian]], [[Romanian language|Romanian]], [[Sicilian language|Sicilian]], [[Catalan language|Catalan]], [[Turkish language|Turkish]], and occasionally in [[French language|French]].</ref> a bare dental click release accompanied by tipping the head upwards signifies "no". [[Libyan Arabic]] apparently has three such sounds.<ref>{{Cite web |title=Libyan Arabic language |url=https://www.omniglot.com/writing/arabic_libyan.htm |access-date=2024-11-14 |website=www.omniglot.com}}</ref> A voiceless nasal [[back-released velar click]] {{IPA|[ʞ]}} is used throughout Africa for [[backchannel (linguistics)|backchannel]]ing. This sound starts off as a typical click, but the action is reversed and it is the rear velar or uvular closure that is released, drawing in air from the throat and nasal passages.  

Lexical clicks occasionally turn up elsewhere. In [[West Africa]], clicks have been reported allophonically, and similarly in French and German, faint clicks have been recorded in rapid speech where consonants such as {{IPA|/t/}} and {{IPA|/k/}} overlap between words.<ref name="germ">{{cite conference|first1=Susanne|last1=Fuchs|first2=Laura|last2=Koenig|first3=Ralf|last3=Winkler|title=Weak clicks in German?|conference=Proceedings of the 16th International Congress of Phonetic Sciences|pages=449–452|year=2007|location=Saarbrücken|url=http://www.icphs2007.de/conference/Papers/1678/1678.pdf|access-date=16 May 2011|archive-date=24 July 2011|archive-url=https://web.archive.org/web/20110724152822/http://www.icphs2007.de/conference/Papers/1678/1678.pdf|url-status=live}}</ref> In [[Rwanda language|Rwanda]], the sequence {{IPA|/mŋ/}} may be pronounced either with an epenthetic vowel, {{IPA|[mᵊ̃ŋ]}}, or with a light bilabial click, {{IPA|[m𐞵̃ŋ]}}—often by the same speaker.

Speakers of [[Gan Chinese]] from [[Ningdu]] county, as well as speakers of Mandarin from Beijing and [[Jilin]] and presumably people from other parts of the country, produce flapped nasal clicks in nursery rhymes with varying degrees of competence, in the words for 'goose' and 'duck', both of which begin with {{IPA|/ŋ/}} in Gan and until recently began with {{IPA|/ŋ/}} in Mandarin as well. In Gan, the nursery rhyme is,
:{{IPA|[tʰien i tsʰak ᵑǃ¡o]}} 天上一隻鵝 'a goose in the sky'
:{{IPA|[ti ha i tsʰak ᵑǃ¡a]}} 地下一隻鴨 'a duck on the ground' 
:{{IPA|[tʰien i tsʰak ᵑǃ¡a]}} 天上一隻鴨 'a duck in the sky'
:{{IPA|[ti ha i tsʰak ᵑǃ¡o]}} 地下一隻鵝 'a goose on the ground'
:{{IPA|[ᵑǃ¡o saŋ ᵑǃ¡o tʰan, ᵑǃ¡o pʰau ᵑǃ¡o]}} 鵝生鵝蛋鵝孵鵝 'a goose lays a goose egg, a goose hatches a goose'
:{{IPA|[ᵑǃ¡a saŋ ᵑǃ¡a tʰan, ᵑǃ¡a pʰau ᵑǃ¡a]}} 鴨生鴨蛋鴨孵鴨 'a duck lays a duck egg, a duck hatches a duck'
where the {{IPA|/ŋ/}} onsets are all pronounced {{IPA|[ᵑǃ¡]}}.<ref>{{cite journal |first=Geoffrey |last=Nathan |title=Clicks in a Chinese Nursery Rhyme |journal=Journal of the International Phonetic Association |volume=31 |issue=2 |year=2001 |pages=223–228 |doi=10.1017/S0025100301002043 }}</ref>

Occasionally other languages are claimed to have click sounds in general vocabulary. This is usually a misnomer for [[ejective consonant]]s, which are found across much of the world.

=== Position in word ===
{{See also|#Phonotactics}}
For the most part, the Southern African [[Khoisan languages]] only use [[root word|root]]-initial clicks.<ref group="note">Exceptions occurs in words borrowed from Bantu languages, which may have click in the middle.</ref> Hadza, Sandawe and several [[Bantu languages]] also allow [[syllable]]-initial clicks within roots. In no language does a click close a syllable or end a word, but since the languages of the world that happen to have clicks consist mostly of CV syllables and allow at most only a limited set of consonants (such as a nasal or a glottal stop) to close a syllable or end a word, ''most'' consonants share the distribution of clicks in these languages.

=== Number of click-types in languages ===
Most languages of the Khoesan families (Tuu, Kxʼa and Khoe) have four click types: {{IPA|{&thinsp;ǀ ǁ ǃ ǂ&thinsp;}}} or variants thereof, though a few have three or five, the last supplemented with either [[bilabial click|bilabial]] {{IPA|{&thinsp;ʘ&thinsp;}}} or [[retroflex click|retroflex]] {{IPA|{&thinsp;𝼊&thinsp;}}}. Hadza and Sandawe in Tanzania have three, {{IPA|{&thinsp;ǀ ǁ ǃ&thinsp;}}}. Yeyi is the only Bantu language with four, {{IPA|{&thinsp;ǀ ǁ ǃ ǂ&thinsp;}}}, while Xhosa and Zulu have three, {{IPA|{&thinsp;ǀ ǁ ǃ&thinsp;}}}, and most other Bantu languages with clicks have fewer.

==Types of clicks==
{{anchor|Click type}}Like other consonants, clicks can be described using four parameters: [[place of articulation]], [[manner of articulation]], [[phonation]] (including glottalisation) and [[airstream mechanism]]. As noted above, clicks necessarily involve at least two closures, which in some cases operate partially independently: an anterior articulation traditionally represented by the special click symbol in the IPA—and a posterior articulation traditionally transcribed for convenience as oral or [[nasal consonant|nasal]], voiced or voiceless, though such features actually apply to the entire consonant. The literature also describes a contrast between [[velar consonant|velar]] and [[uvular consonant|uvular]] rear articulations for some languages.

In some languages that have been reported to make this distinction, such as [[Nǁng language|Nǁng]], all clicks have a uvular rear closure, and the clicks explicitly described as uvular are in fact cases where the uvular closure is independently audible: contours of a click into a pulmonic or ejective component, in which the click has two release bursts, the forward (click-type) and then the rearward (uvular) component. "Velar" clicks in these languages have only a single release burst, that of the forward release, and the release of the rear articulation isn't audible. However, in other languages all clicks are velar – for example Hadza, or uvular – for example Xhosa; and a few languages, such as [[Taa language|Taa]], have a true velar–uvular distinction that depends on the place rather than the timing of rear articulation and that is audible in the quality of the vowel.

Regardless, in most of the literature the stated place of the click is the anterior articulation (called the ''release'' or ''influx),'' whereas the manner is ascribed to the posterior articulation (called the ''accompaniment'' or ''efflux).'' The anterior articulation defines the ''click type'' and is written with the IPA letter for the click (dental {{angbr IPA|ǀ}}, alveolar {{angbr IPA|ǃ}}, etc.), whereas the traditional term 'accompaniment' conflates the categories of manner (nasal, affricated), phonation (voiced, aspirated, breathy voiced, glottalised), as well as any change in the airstream with the release of the posterior articulation (pulmonic, ejective), all of which are transcribed with additional letters or diacritics, as in the ''nasal alveolar click'', {{angbr IPA|ǃŋ}} or {{angbr IPA|ᵑǃ}} or—to take an extreme example—the ''voiced (uvular) ejective alveolar click'', {{angbr IPA|ᶢǃ͡qʼ}}.

The size of click inventories ranges from as few as three (in [[Sesotho phonology#Consonants|Sesotho]]) or four (in [[Dahalo language|Dahalo]]), to dozens in the [[Kxʼa languages|Kxʼa]] and [[Tuu languages|Tuu]] (Northern and Southern Khoisan) languages. [[Taa language|Taa]], the last vibrant language in the latter family, has 45 to 115 click phonemes, depending on analysis (clusters vs. contours), and over 70% of words in the dictionary of this language begin with a click.<ref>{{Harvnb|Ladefoged|Maddieson|1996|p=246}}.</ref>

Clicks appear more [[stop consonant|stop]]-like (sharp/abrupt) or [[affricate]]-like (noisy) depending on their place of articulation: In southern Africa, clicks involving an [[apical consonant|apical]] [[alveolar consonant|alveolar]] or [[laminal consonant|laminal]] [[postalveolar consonant|postalveolar]] closure are acoustically abrupt and sharp, like stops, whereas [[labial consonant|labial]], [[dental consonant|dental]] and [[lateral consonant|lateral]] clicks typically have longer and acoustically noisier click types that are superficially more like affricates. In East Africa, however, the alveolar clicks tend to be [[flap consonant|flapped]], whereas the lateral clicks tend to be more sharp.

==Transcription==
{{Further|click letter}}
The six places of articulation of clicks that have dedicated letters in the [[International Phonetic Alphabet]] (IPA) are [[labial click|labial]] {{angbr IPA|ʘ}}, [[dental click|dental]] {{angbr IPA|ǀ}}, [[lateral click|lateral]] {{angbr IPA|ǁ}}, [[palatal click|palatal]] ("palato-alveolar") {{angbr IPA|ǂ}}, [[postalveolar click|(post)alveolar]] ("retroflex") {{angbr IPA|ǃ}} and [[retroflex click|retroflex]], with the 'implicit' letter {{angbr IPA|𝼊}}. In most languages, the alveolar and palatal types involve an abrupt release; that is, they are sharp popping sounds with little frication (turbulent airflow). The labial, dental and lateral types, on the other hand, are typically noisy: they are longer, lip- or tooth-sucking sounds with turbulent airflow, and are sometimes called affricates. (This applies to the forward articulation; both may also have either an affricate or non-affricate rear articulation as well.) The [[apical consonant|apical]] places, {{IPA|ǃ}} and {{IPA|ǁ}}, are sometimes called "grave", because their pitch is dominated by low frequencies; whereas the [[laminal consonant|laminal]] places, {{IPA|ǀ}} and {{IPA|ǂ}}, are sometimes called "acute", because they are dominated by high frequencies. (At least in the [[Nǁng language]] and [[Juǀʼhoan language|Juǀʼhoan]], this is associated with a difference in the placement of the rear articulation: "grave" clicks are [[uvular consonant|uvular]], whereas "acute" clicks are [[pharyngeal consonant|pharyngeal]].) Thus the alveolar click {{IPA|[kǃ]}} sounds something like a cork pulled from a bottle (a low-pitch pop), at least in Xhosa; whereas the dental click {{IPA|[kǀ]}} is like English ''tsk! tsk!,'' a high-pitched sucking on the incisors. The lateral clicks are pronounced by sucking on the molars of one or both sides. The labial click {{IPA|[kʘ]}} is different from what many people associate with a kiss: the lips are pressed more-or-less flat together, as they are for a {{IPA|[p]}} or an {{IPA|[m]}}, not rounded as they are for a {{IPA|[w]}}.

The most populous languages with clicks, Zulu and Xhosa, use the letters ''c, q, x,'' by themselves and in [[digraph (orthography)|digraphs]], to write click consonants. Most Khoisan languages, on the other hand (with the notable exceptions of [[Naro language|Naro]] and [[Sandawe language|Sandawe]]), use a more iconic system based on the [[Vertical bar|pipe]] {{angbr|<nowiki>|</nowiki>}}. (The exclamation point for the "retroflex" click was originally a pipe with a subscript dot, along the lines of ''ṭ, ḍ, ṇ'' used to transcribe the retroflex consonants of India.) There are also two main conventions for the second letter of the digraph as well: voicing may be written with ''g'' and uvular affrication with ''x'', or voicing with ''d'' and affrication with ''g'' (a convention of Afrikaans). In two orthographies of Juǀʼhoan, for example, voiced {{IPA|/ᶢǃ/}} is written ''g!'' or ''dq'', and {{IPA|/ᵏǃ͡χ/}} ''!x'' or ''qg''. In languages without {{IPA|/ᵏǃ͡χ/}}, such as Zulu, {{IPA|/ᶢǃ/}} may be written ''gq''.

{| class=wikitable
|+ Competing orthographies
!rowspan=2| !!rowspan=2|labial!!colspan=2|laminal!!colspan=2|apical !!subapical
|-
!dental!!palatal!!alveolar!!lateral!!retroflex
|- align=center
! Lepsius (1855)
| ||{{IPA|ǀ}}||{{IPA|ǀ́ }}||{{IPA|ǀ̣ }}||{{IPA|ǀǀ}}||
|- align=center
! Bantuist
| ''{{IPA|pc}}'' ||{{IPA|c}}|| ''{{IPA|v ç tc<br />qc}}'' {{ref|pal|b}} ||{{IPA|q}}||{{IPA|x}}||
|- align=center
! IPA (1921)
| || {{IPA|ʇ}}||{{IPA|ʞ}}{{ref|doke|a}}||{{IPA|ʗ}}||{{IPA|ʖ}}||
|- align=center
! expanded IPA (1926-1984)
|{{IPA|ɋ}}||{{IPA|ʇ}}||{{IPA|𝼋}}||{{IPA|ʗ}}||{{IPA|ʖ}}||{{IPA|ψ}}
|- align=center
! IPA (1989)
|{{IPA|ʘ}}||{{IPA|ǀ}}||{{IPA|ǂ}}||{{IPA|ǃ}}||{{IPA|ǁ}}||{{IPA|𝼊}}
|}
# {{note|doke|a}} {{angbr IPA|ʞ}} was proposed as the IPA letter for a palatal click by [[Daniel Jones (phonetician)|Daniel Jones]], but in his writing he called it 'velar', which was evidently misunderstood by other phoneticians. Replacement with {{angbr|🡣}} was proposed by [[Clement Martyn Doke|Clement Doke]],<ref>{{cite book |first=Clement M. |last=Doke |orig-year=1926 |year=1969 |title=The phonetics of the Zulu language |location=Johannesburg |publisher=University of the Witwatersrand Press }}</ref> and with {{angbr IPA|𝼋}} by [[Douglas Martyn Beach|Beach]].<ref>{{cite book |first=Douglas Martyn |last=Beach |year=1938 |title=The phonetics of the Hottentot language |publisher=W. Heffer & sons |oclc= }}</ref> (The former is not supported by Unicode, and is here substituted with an arrow.) Doke and Beach used [[click letters|additional letters]] for voiced and nasal clicks, but these did not catch on.
# {{note|pal|b}} The labial and palatal clicks do not occur in written Bantu languages. However, the palatal clicks have been romanized in Naron, [[Juǀʼhoan language|Juǀʼhõasi]] and !Xun,{{which|date=December 2012}} where they have been written {{angbr|tc}}, {{angbr|ç}} and {{angbr|qc}}, respectively. In the 19th century, palatal clicks were sometimes written with the letter {{angbr|v}}, which may have been the source of the Doke letter {{angbr|🡣}}.

There are a few less-well-attested articulations. <!--Note: the 2nd lateral click in Mangetti Dune could not be reproduced, and the authors have retracted their claim (vd. Miller & Shah 2009). Former text: ''such as a noisy laminal denti-alveolar lateral articulation ({{angbr IPA|⦀}} in an ''ad hoc'' transcription), which contrasts with an apical postalveolar lateral in Mangetti Dune !Kung;''--> A reported subapical retroflex articulation {{angbr IPA|𝼊}} in Grootfontein !Kung<ref group=note>{{angbr|⦀}} (a triple pipe) in Doke (1954) and Cole (1966) is an ''ad hoc'' phonetic pipe letter for Doke's orthographic click letter {{angbr|ψ}}.</ref> turns out to be alveolar with lateral release, {{angbr IPA|ǃ𐞷}}; Ekoka !Kung has a fricated alveolar click with an s-like release, provisionally transcribed {{angbr IPA|ǃ͡s}}; and Sandawe has a "slapped" alveolar click, provisionally transcribed {{angbr IPA|ǃ¡}} (in turn, the lateral clicks in Sandawe are more abrupt and less noisy than in southern Africa). However, the Khoisan languages are poorly attested, and it is quite possible that, as they become better described, more click articulations will be found.

Formerly when a click consonant was transcribed, two symbols were used, one for each articulation, and connected with a tie bar. This is because a click such as {{IPA|[ɢ͡ǀ]}} was analysed as a voiced uvular rear articulation {{IPA|[ɢ]}} pronounced simultaneously with the forward ingressive release {{IPA|[ǀ]}}. The symbols may be written in either order, depending on the analysis: {{angbr IPA|ɢ͡ǀ}} or {{angbr IPA|ǀ͡ɢ}}. However, a tie bar was not often used in practice, and when the manner is [[tenuis consonant|tenuis]] (a simple {{IPA|[k]}}), it was often omitted as well. That is, {{angbr IPA|ǂ}} = {{angbr IPA|kǂ}} = {{angbr IPA|ǂk}} = {{angbr IPA|k͡ǂ}} = {{angbr IPA|ǂ͡k}}. Regardless, elements that do not overlap with the forward release are usually written according to their temporal order: Prenasalisation is always written first ({{angbr IPA|ɴɢ͡ǀ}} = {{angbr IPA|ɴǀ͡ɢ}} = {{angbr IPA|ɴǀ̬}}), and the non-lingual part of a contour is always written second ({{angbr IPA|k͡ǀʼqʼ}} = {{angbr IPA|ǀ͡kʼqʼ}} = {{angbr IPA|ǀ͡qʼ}}).

However, it is common to analyse clicks as simplex segments, despite the fact that the front and rear articulations are independent, and to use diacritics to indicate the rear articulation and the accompaniment. At first this tended to be {{angbr IPA|ᵏǀ, ᶢǀ, ᵑǀ}} for {{angbr IPA|k͡ǀ, ɡ͡ǀ, ŋ͡ǀ}}, based on the assumption that the rear articulation was velar; but as it has become clear that the rear articulation is often uvular or even pharyngeal even when there is no velar–uvular contrast, voicing and nasalisation diacritics more in keeping with the IPA have started to appear: {{angbr IPA|ǀ̥, ǀ̬, ǀ̃, ŋǀ̬}} for {{angbr IPA|ᵏǀ, ᶢǀ, ᵑǀ, ŋᶢǀ}}.

{| class="wikitable"
|+Variation in the transcription of accompaniments
|-
! !! Tenuis !! Aspirated !! Voiced !! Nasal !! Delayed ("uvular") !! True uvular
|-
! rowspan=2|Tie bars
| {{IPA|k͡ǀ}} || {{IPA|k͡ǀʰ}} || {{IPA|ɡ͡ǀ}} || {{IPA|ŋ͡ǀ}} || {{IPA|ǀ͡k, ǀ͡kʰ, ǀ͡ɡ, ǀ͡ŋ}} || {{IPA|q͡ǀ, ǀ͡q}} etc.
|-
| {{IPA|k͜ǀ}} || {{IPA|k͜ǀʰ}} || {{IPA|ɡ͜ǀ}} || {{IPA|ŋ͜ǀ}} || {{IPA|ǀ͜k, ǀ͜kʰ, ǀ͜ɡ, ǀ͜ŋ}} || {{IPA|q͜ǀ, ǀ͜q}} etc.
|-
! Digraphs
| {{IPA|kǀ}} || {{IPA|kǀʰ}} || {{IPA|ɡǀ}} || {{IPA|ŋǀ}} || {{IPA|ǀk, ǀkʰ, ǀɡ, ǀŋ}} || {{IPA|qǀ, ǀq}} etc.
|-
! Superscripts
| {{IPA|ᵏǀ}} || {{IPA|ᵏǀʰ}} || {{IPA|ᶢǀ}} || {{IPA|ᵑǀ}} || {{IPA|ǀᵏ, ǀᵏʰ, ǀᶢ, ǀᵑ}} || {{IPA|𐞥ǀ, ǀ𐞥}} etc.
|-
! Diacritics
| {{IPA|ǀ̥}} || {{IPA|ǀʰ}} || {{IPA|ǀ̬}} || {{IPA|ǀ̬̃}} || NA || NA
|}

In practical orthography, the voicing or nasalisation is sometimes given the anterior place of articulation: ''dc'' for {{IPA|ᶢǀ}} and ''mʘ'' for {{IPA|ᵑʘ}}, for example.

In the literature on Damin, the clicks are transcribed by adding {{angbr|!}} to the homorganic nasal: {{angbr|m!, nh!, n!, rn!}}.

==Places of articulation==
{{main|bilabial click|dental click|palatal click|alveolar click|lateral click|retroflex click|velar click}}

[[Place of articulation|Places of articulation]] are often called click ''types, releases,'' or ''influxes,'' though 'release' is also used for the accompaniment/efflux. There are seven or eight known places of articulation, not counting slapped or egressive clicks. These are ''(bi)labial affricated'' {{IPA|ʘ}}, or "bilabial"; ''laminal denti-alveolar affricated'' {{IPA|ǀ}}, or "dental"; ''apical (post)alveolar plosive'' {{IPA|ǃ}}, or "alveolar"; ''laminal palatal plosive'' {{IPA|ǂ}}, or "palatal"; ''laminal palatal affricated'' {{IPA|ǂᶴ}} (known only from [[Ekoka !Kung]]); ''subapical postalveolar'' {{IPA|𝼊}}, or "[[Retroflex click|retroflex]]" (only known from [[Central !Kung]] and possibly Damin); and ''apical (post)alveolar lateral'' {{IPA|ǁ}}, or "lateral".

{| class="wikitable"
|+Place of articulation of initial release<ref>Click releases are not in themselves consonants (segments). To transcribe a click consonant, a second IPA letter is needed for the rear place of articulation, as in {{angbr IPA|k͡ǂ}} or {{angbr IPA|ǂ͡qχʼ}}</ref>
|-
![[labial click|Labial]]||[[dental click|Dental]]||[[alveolar click|Alveolar]]||[[slapped click|Slapped]]||[[retroflex click|Retroflex]]||[[domed click|Domed]]||[[palatal click|Palatal]]||[[lateral click|Lateral]]||[[linguolabial click|Linguolabial]]||[[velar click|Velar]]
|-align=center
|rowspan=2|{{IPA|ʘ}}||rowspan=2|{{IPA|ǀ}}||rowspan=2|{{IPA|ǃ}}||{{IPA|ǃ¡}}||rowspan=2|{{IPA|𝼊}}||rowspan=2|{{IPA|ǂᶴ}} ({{IPA|𝼋}})||rowspan=2|{{IPA|ǂ}}||rowspan=2|{{IPA|ǁ}}||{{IPA|ǀ̼}}||{{IPA|ʞ}}
|-
|(allophonic)||colspan=2|(paralexical only)
|}

Languages illustrating each of these articulations are listed below. Given the poor state of documentation of Khoisan languages, it is quite possible that additional places of articulation will turn up. No language is known to contrast more than five.

{| class=wikitable
! Click place<br />inventory !! Languages !! Notes
|-
| 1 release, variable {{IPA|ǀ ~ ǁ}} || [[Dahalo language|Dahalo]] || Various nasal clicks only.
|-
| 1 release, variable {{IPA|ǀ ~ ǃ}} || [[Sotho language|Sotho]], [[Swazi language|Swazi]] || In Sotho the clicks tend to be alveolar, in Swazi dental.
|-
| 1 release, variable {{IPA|ǀ ~ ǃ ~ ǁ or ǂ}} || [[Fwe language|Fwe]], [[Gciriku language|Gciriku]] || Tend to be dental.
|-
| 3 releases, {{IPA|ǀ}}, {{IPA|ǂ}}, {{IPA|ǁ}} || [[Kwadi language|Kwadi]] || {{IPA|ǂ}} and {{IPA|ǁ}} not found with all manners, but these may be accidental gaps, as Kwadi is poorly attested
|-
| 3 releases, {{IPA|ǀ}}, {{IPA|ǃ}}, {{IPA|ǁ}} || [[Sandawe language|Sandawe]], [[Hadza language|Hadza]], [[Xhosa language|Xhosa]], [[Zulu language|Zulu]] || In Sandawe, {{IPA|ǃ}} is often "slapped" {{IPA|[ǃ¡]}}.
|-
| 3–4 releases, {{IPA|ʘ}}, {{IPA|ǀ}}, ({{IPA|ǃ}},) {{IPA|ǁ}} || [[ǁXegwi language|ǁXegwi]] || {{IPA|ǃ}} reacquired in loans
|-
| 4 releases, {{IPA|ǀ}}, {{IPA|ǂ}}, {{IPA|ǃ}}, {{IPA|ǁ}} || [[Korana language|Korana]], [[Khoekhoe language|Khoekhoe]], [[Yeyi language|Yeyi]], [[Juǀʼhoan dialect|Juǀʼhoan]] ||
|-
| 4 releases, {{IPA|ǀ}}, {{IPA|ǂᶴ}}, {{IPA|ǃ}}, {{IPA|ǁ}} || [[Ekoka !Kung]] || 
|-
| 5 releases, {{IPA|ʘ}}, {{IPA|ǀ}}, {{IPA|ǂ}}, {{IPA|ǃ}}, {{IPA|ǁ}} || [[ǂHoan language|ǂHõã]], [[Nǁng language|Nǀu]], [[ǀXam language|ǀXam]], [[Taa language|Taa]] ||
|-
| 5 releases, {{IPA|ǀ}}, {{IPA|ǂ}}, {{IPA|ǃ}}, {{IPA|𝼊}}, {{IPA|ǁ}} || [[Grootfontein !Kung]] ||
|-
| 5 releases, {{IPA|ʘ}}, {{IPA|ʘ↑}}, {{IPA|ǀ}}, {{IPA|ǃ}}, {{IPA|𝼊}} || [[Damin]] || Aside from {{IPA|/ʘ↑/}}, which is not technically a click, all are nasal.
|}

Extra-linguistically, [[Coatlán Zapotec]] of [[Mexico]] uses a [[linguolabial]] click, {{IPA|[ǀ̼ʔ]}}, as [[mimesis]] for a pig drinking water,<ref name="Azcona">{{cite web |first=Rosemary |last=Beam de Azcona |title=Sound Symbolism |url=http://www.linguistics.berkeley.edu/~rosemary/55-fall2003-onomatopoeia.pdf |archive-url=https://web.archive.org/web/20070623145306/http://www.linguistics.berkeley.edu/~rosemary/55-fall2003-onomatopoeia.pdf |archive-date=23 June 2007 }}</ref> and several languages, such as [[Wolof language|Wolof]], use a [[velar click]] {{IPA|[ʞ]}}, long judged to be physically impossible, for [[Backchannel (linguistics)|backchanneling]] and to express approval.<ref>{{cite book |first=Lenore |last=Grenoble |year=2014 |chapter=Verbal gestures: Toward a field-based approach to language description |editor-last=Plungian |title=Язык, константы, переменные : памяти Александра Евгеньевича Кибрика |trans-title=Language. Constants. Variables: In memory of A. E. Kibrik |pages=105–118 |publisher=Aleteija |location=Saint Petersburg |isbn=978-5-906705-14-3 }}</ref> An extended dental click with lip pursing or compression ("[[sucking-teeth]]"), variable in sound and sometimes described as intermediate between {{IPA|[ǀ]}} and {{IPA|[ʘ]}}, is found across West Africa, the Caribbean and into the United States.

The exact place of the alveolar clicks varies between languages. The lateral, for example, is alveolar in Khoekhoe but postalveolar or even palatal in Sandawe; the central is alveolar in Nǀuu but postalveolar in Juǀʼhoan.<ref>{{cite book |first=Amanda |last=Miller |year=2011 |chapter=The Representation of Clicks |title=The Blackwell Companion to Phonology }}</ref>

===Names found in the literature===

The terms for the click types were originally developed by Bleek in 1862.<ref>{{cite book |first=Wilhelm |last=Bleek |year=1862 |title=A Comparative Grammar of South African Languages |volume=1 |pages=12–13 }}</ref> Since then there has been some conflicting variation. However, apart from "cerebral" (retroflex), which was found to be an inaccurate label when true retroflex clicks were discovered, Bleek's terms are still considered normative today. Here are the terms used in some of the main references.

{|class="wikitable"
|+ Names in the literature
! Click type !! Bleek (1862) !! Doke (1926)|| IPA (1928) || Beach (1938) || IPA (1949) || IPA (1989) || Unicode || Miller et al. (2009)<ref>{{cite journal |last=Miller |last2=Brugman |last3=Sands |last4=Namaseb |last5=Exter |last6=Collins |year=2009 |title=Differences in airstream and posterior place of articulation among Nǀuu clicks |journal=Journal of the International Phonetic Association |volume=39 |issue=2 |pages=129–161 |doi=10.1017/S0025100309003867 }}</ref> || Vossen (2013)<ref>{{cite book |first=Rainer |last=Vossen |authorlink=Rainer Vossen |year=2013 |chapter=Introduction |title=The Khoesan Languages |publisher=Routledge |isbn= }}</ref>|| other
|-
| {{IPA|ǀ}} || dental || dental || dental || dental affricative || dental || dental || dental || denti-pharyngeal || dental || alveolar affricated; denti-alveolar; apico-lamino-dental
|-
| {{IPA|ǃ}} || cerebral || palato-alveolar ||cerebral || alveolar implosive || retroflex || (post-)alveolar || retroflex || central alveo-uvular || alveolar || palatal; palatal retroflex; apico-palatal
|-
| {{IPA|ǁ}} || lateral || lateral || alveolar lateral || lateral affricative || lateral || (alveolar) lateral || lateral || lateral alveo-uvular || lateral-alveolar || post-alveolar lateral; lateral apico-alveo-palatal
|-
| {{IPA|ǂ}} || palatal || alveolar|| velar || denti-alveolar implosive || velar || palatoalveolar || alveolar || palato-pharyngeal || palatal || alveolar instantaneous; dental
|-
| {{IPA|ʘ}} ||  || || ||  ||  || bilabial || bilabial || labio-uvular || bilabial || labial
|}

The dental, lateral and bilabial clicks are rarely confused, but the palatal and alveolar clicks frequently have conflicting names in older literature, and non-standard terminology is fossilized in Unicode. However, since Ladefoged & Traill (1984) clarified the places of articulation,<ref>{{Cite journal |last=Ladefoged |first=Peter |last2=Traill |first2=Anthony |date=1984 |title=Linguistic Phonetic Descriptions of Clicks |url=https://www.jstor.org/stable/414188 |journal=Language |volume=60 |issue=1 |pages=1–20 |doi=10.2307/414188 |issn=0097-8507|url-access=subscription }}</ref> the terms listed under Vossen (2013) in the table above have become standard, apart from such details as whether in a particular language {{IPA|ǃ}} and {{IPA|ǁ}} are alveolar or postalveolar, or whether the rear articulation is velar, uvular or pharyngeal, which again varies between languages (or may even be contrastive within a language).

==Manners of articulation==
{{main|nasal click|glottalised click|pulmonic-contour click|ejective-contour click}}
Click manners are often called click ''accompaniments'' or ''effluxes'', but both terms have met with objections on theoretical grounds.

There is a great variety of click manners, both simplex and complex, the latter variously analysed as consonant [[consonant cluster|clusters]] or [[contour (linguistics)|contours]]. With so few click languages, and so little study of them, it is also unclear to what extent clicks in different languages are equivalent. For example, the {{IPA|[ǃkˀ]}} of Khoekhoe, {{IPA|[ǃkˀ ~ ŋˀǃk]}} of Sandawe and {{IPA|[ŋ̊ǃˀ ~ ŋǃkˀ]}} of Hadza may be essentially the same phone; no language distinguishes them, and the differences in transcription may have more to do with the approach of the linguist than with actual differences in the sounds. Such suspected allophones/allographs are listed on a common row in the table below.

Some Khoisan languages are [[Linguistic typology|typologically]] unusual in allowing mixed [[phonation|voicing]] in non-click consonant clusters/contours, such as {{IPA| ̬d̥sʼk͡x}}, so it is not surprising that they would allow mixed voicing in clicks as well. This may be an effect of epiglottalised voiced consonants, because voicing is incompatible with epiglottalisation.

===Phonation===
As do other consonants, clicks vary in [[phonation]]. Oral clicks are attested with four phonations: [[tenuis consonant|tenuis]], [[aspirated consonant|aspirated]], [[voiced consonant|voiced]] and [[breathy voice]]d (murmured). Nasal clicks may also vary, with plain voiced, breathy voiced / murmured nasal, aspirated and unaspirated voiceless clicks attested (the last only in Taa). The aspirated nasal clicks are often said to have 'delayed aspiration'; there is nasal airflow throughout the click, which may become voiced between vowels, though the aspiration itself is voiceless. A few languages also have pre-glottalised nasal clicks, which have very brief prenasalisation<!--creaky-voiced nasal?--> but have not been phonetically analysed to the extent that other types of clicks have.

All languages have nasal clicks, and all but [[Dahalo language|Dahalo]] and [[Damin]] also have oral clicks. All languages but Damin have at least one phonation contrast as well.

===Complex clicks===
Clicks may be pronounced with a third place of articulation, glottal. A [[glottal stop]] is made during the hold of the click; the (necessarily voiceless) click is released, and then the glottal hold is released into the vowel. Glottalised clicks are very common, and they are generally nasalised as well. The nasalisation cannot be heard during the click release, as there is no pulmonic airflow, and generally not at all when the click occurs at the beginning of an utterance, but it has the effect of nasalising preceding vowels, to the extent that the glottalised clicks of Sandawe and Hadza are often described as prenasalised when in medial position. Two languages, [[Gǀwi dialect|Gǀwi]] and [[Yeyi language|Yeyi]], contrast plain and nasal glottalised clicks, but in languages without such a contrast, the glottalised click is nasal. Miller (2011) analyses the glottalisation as phonation, and so considers these to be simple clicks.

Various languages also have prenasalised clicks, which may be analysed as consonant sequences. [[Sotho language|Sotho]], for example, allows a syllabic nasal before its three clicks, as in ''nnqane'' 'the other side' (prenasalised nasal) and ''seqhenqha'' 'hunk'.

There is ongoing discussion as to how the distinction between what were historically described as 'velar' and 'uvular' clicks is best described. The 'uvular' clicks are only found in some languages, and have an extended pronunciation that suggests that they are more complex than the simple ('velar') clicks, which are found in all. Nakagawa (1996) describes the extended clicks in [[Gǀwi dialect|Gǀwi]] as [[consonant cluster]]s, sequences equivalent to English ''st'' or ''pl'', whereas Miller (2011) analyses similar sounds in several languages as click–non-click [[contour (linguistics)|contours]], where a click transitions into a pulmonic or ejective articulation within a single segment, analogous to how English ''ch'' and ''j'' transition from occlusive to fricative but still behave as unitary sounds. With ejective clicks, for example, Miller finds that although the ejective release follows the click release, it is the rear closure of the click that is ejective, not an independently articulated consonant. That is, in a simple click, the release of the rear articulation is not audible, whereas in a contour click, the rear (uvular) articulation is audibly released after the front (click) articulation, resulting in a double release.

These contour clicks may be ''linguo-pulmonic'', that is, they may transition from a click (lingual) articulation to a normal pulmonic consonant like {{IPAblink|ɢ}} (e.g. {{IPA|[ǀ͡ɢ]}}); or ''linguo-glottalic'' and transition from lingual to an ejective consonant like {{IPAblink|qʼ}} (e.g. {{IPA|[ǀ͡qʼ]}}): that is, a sequence of ingressive (lingual) release + egressive (pulmonic or glottalic) release. In some cases there is a shift in place of articulation as well, and instead of a uvular release, the uvular click transitions to a velar or [[Epiglottal consonant|epiglottal]] release (depending on the description, {{IPA|[ǂ͡kxʼ]}} or {{IPA|[ǂᴴ]}}). Although [[homorganic]] {{IPA|[ǂ͡χʼ]}} does not contrast with heterorganic {{IPA|[ǂ͡kxʼ]}} in any known language, they are phonetically quite distinct (Miller 2011).

Implosive clicks, i.e. velar {{IPA|[ɠ͡ʘ ɠ͡ǀ ɠ͡ǃ ɠ͡ǂ ɠ͡ǁ]}}, uvular {{IPA|[ʛ͡ʘ ʛ͡ǀ ʛ͡ǃ ʛ͡ǂ ʛ͡ǁ]}}, and ''de facto'' front-closed palatal {{IPA|[ʄ͡ʘ ʄ͡ǀ ʄ͡ǃ ʄ͡ǁ]}} are not only possible but easier to produce than modally voiced clicks. However, they are not attested in any language.<ref>{{cite book |first=Kenneth |last=Pike |editor-first=Ruth |editor-last=Brend |year=1972 |title=Selected Writings: To Commemorate the 60th Birthday of Kenneth Lee Pike |page=226 }}</ref>

The 'Khoisan' languages, as well as Bantu Yeyi, have glottalized nasal clicks. Contour clicks are restricted to southern Africa, but are very common there: they are found in all members of the Tuu, Kxʼa and Khoe families, as well as in the Bantu language Yeyi.

===Variation among languages===
In a comparative study of clicks across various languages, using her own field work as well as phonetic descriptions and data by other field researchers, Miller (2011) posits 21 types of clicks that contrast in manner or airstream.<ref group=note>Not counting the egressive "spurt" in Damin, and three additional voiced manners in Western ǃXoo, which pair up with voiceless manners.</ref> The [[homorganic]] and heterorganic affricated ejective clicks do not contrast in any known language, but are judged dissimilar enough to keep separate. Miller's conclusions differ from those of the primary researcher of a language; see the individual languages for details.
* [[Taa language|Taa]] (ǃXóõ) and [[Nǁng language|Nǁng]] (Nǀuu) are [[Tuu languages]], from the two branches of that family.
* [[ǂʼAmkoe language|ǂʼAmkoe]] (ǂHoan) and [[Juǀʼhoan language|Juǀʼhoan]] (ǃKung) are [[Kxʼa languages]], from the two branches of that family.
* [[Korana language|Korana]] and [[Gǀwi language|Gǀui]] (Gǁana) are [[Khoe languages]], from the two branches of that family.
(all spoken primarily in [[South Africa]], [[Namibia]] and [[Botswana]]; [[Khoekhoe language|Khoekhoe]] is similar to Korana except it has lost ejective {{IPA|/ᵏꞰ͡χʼ/}})
* [[Sandawe language|Sandawe]] and [[Hadza language|Hadza]] are [[language isolate]]s spoken in [[Tanzania]]
* [[Dahalo language|Dahalo]] is a [[Cushitic languages|Cushitic]] language of [[Kenya]]
* [[Xhosa language|Xhosa]] and [[Yeyi language|Yeyi]] are [[Bantu languages]], from the two geographic areas of that family that have acquired clicks.
([[Zulu language|Zulu]] is similar to Xhosa apart from not having {{IPA|/ᵑꞰˀ/}})
* [[Damin]] was an initiation jargon in northern [[Australia]].

Each language below is illustrated with Ʞ as a placeholder for the different click types. Under each language are the orthography (in italics, with old forms in parentheses), the researchers' transcription (in {{angbr|angle brackets}}), or allophonic variation (in [brackets]). Some languages also have labialised<!--not just Dahalo--> or prenasalised clicks in addition to those listed below.

<div style="margin:0 auto;overflow:scroll;width:auto;max-width:100%">
{| class=wikitable
! colspan=3 rowspan=2 | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Language ||  colspan=2| Tuu ||  colspan=2| Kxʼa ||  colspan=2| Khoe || rowspan=2| Sandawe || rowspan=2| Hadza|| Cushitic || colspan=2| Bantu || Australian
|-
! Taa || Nǁng || ǂʼAmkoe || Juǀʼhoan<ref group=note>Ekoka ǃKung has an additional manner, {{IPA|ˀᵑꞰ}}. Grootfontein and Mangetti Dune ǃKung, on the other hand, have a substantially smaller inventory: {{IPA|ᵏꞰ, ᶢꞰ, Ʞʰ, ᵑꞰ, ᵑ̊Ʞʱ, ᵑꞰˀ, Ʞ͡χ, Ʞ͡kxʼ}}.</ref> || Korana || Gǀui || Dahalo || Xhosa || Yeyi || Damin
|-
! colspan=3 | Manner&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
| colspan=3 align=center bgcolor="#f2f2f2" | {{IPA|ʘ, ǂ, ǃ, ǁ, ǀ}} || colspan=3 align=center bgcolor="#f2f2f2" | {{IPA|ǂ, ǃ, ǁ, ǀ}} || colspan=2 align=center bgcolor="#f2f2f2" | {{IPA|ǃ, ǁ, ǀ}} || align=center bgcolor="#f2f2f2" | {{IPA|ǀ}} || align=center bgcolor="#f2f2f2" | {{IPA|ǃ, ǁ, ǀ}} || align=center bgcolor="#f2f2f2" | {{IPA|ǂ, ǃ, ǁ, ǀ}} || align=center bgcolor="#f2f2f2" | {{IPA|ʘ, 𝼊, ǃ, ǀ}}
|-
|rowspan=4|Simple<br />oral<br />click
| ''[[Tenuis consonant|Tenuis]]''|| bgcolor="#c0c0f0" align=center | {{IPA|/ᵏꞰ/}}
<!-- !Xoo -->| bgcolor="#f0c0c0" align=center | {{angbr|Ʞ}}*
<!-- N/uu -->| bgcolor="#f0c0c0" align=center | {{angbr|Ʞ}}
<!-- =Hoan -->| bgcolor="#f0c0c0" align=center | {{IPA|[ᵏꞰ]}}
<!-- Ju/hoan -->| bgcolor="#f0c0c0" align=center | ''Ʞ (c, ç, q, x)''
<!-- Korana -->| bgcolor="#f0c0c0" align=center | ''Ʞg''
<!-- G/ui -->| bgcolor="#f0c0c0" align=center | {{angbr|kꞰ}}
<!-- Sandawe -->| bgcolor="#f0c0c0" align=center | ''c, q, x''
<!-- Hadza -->| bgcolor="#f0c0c0" align=center | ''c, q, x (Ʞ)'' || 
<!-- Xhosa -->| bgcolor="#f0c0c0" align=center | ''c, q, x''
<!-- Yeyi -->| bgcolor="#f0c0c0" align=center | {{angbr|Ʞ}} ||
|-
| ''Voiced''|| bgcolor="#c0c0f0" align=center | {{IPA|/ᶢꞰ/}}
<!-- !Xoo -->| bgcolor="#f0c0c0" align=center | {{angbr|gꞰ}}*
<!-- N/uu -->| bgcolor="#f0c0c0" align=center | {{angbr|ᶢꞰ}}
<!-- =Hoan -->| bgcolor="#f0c0c0" align=center | {{IPA|[ᶢꞰ]}}
<!-- Ju/hoan -->| bgcolor="#f0c0c0" align=center | ''gꞰ (dq etc.)'' || 
<!-- G/ui -->| bgcolor="#f0c0c0" align=center | {{angbr|gꞰ}}
<!-- Sandawe -->| bgcolor="#f0c0c0" align=center | ''gq etc.''<br />{{IPA|[ᶢꞰ}} ~ {{IPA|ŋᶢꞰ]}} ||  ||  || 
<!-- Yeyi -->| bgcolor="#f0c0c0" align=center | {{angbr|gꞰ}} ||
|-
| ''Aspirated''|| bgcolor="#c0c0f0" align=center | {{IPA|/ᵏꞰʰ/}}
<!-- !Xoo -->| bgcolor="#f0c0c0" align=center | {{angbr|Ʞh}}*
<!-- N/uu -->| bgcolor="#f0c0c0" align=center | {{angbr|Ʞʰ}}
<!-- =Hoan -->| bgcolor="#f0c0c0" align=center | {{IPA|[ᵏꞰʰ]}}
<!-- Ju/hoan -->| bgcolor="#f0c0c0" align=center | ''Ʞh (qh etc.)''
<!-- Korana -->| bgcolor="#f0c0c0" align=center | ''Ʞkh''
<!-- G/ui -->| bgcolor="#f0c0c0" align=center | {{angbr|kꞰh}}
<!-- Sandawe -->| bgcolor="#f0c0c0" align=center | ''qh etc.''
<!-- Hadza -->| bgcolor="#f0c0c0" align=center | ''qh etc. (Ʞh)'' || 
<!-- Xhosa -->| bgcolor="#f0c0c0" align=center | ''qh etc.''
<!-- Yeyi -->| bgcolor="#f0c0c0" align=center | {{angbr|Ʞh}} (= Ʞx ?) ||
|-
| ''Breathy-voiced''|| bgcolor="#c0c0f0" align=center | {{IPA|/ᶢꞰʱ/}}
<!-- !Xoo -->| bgcolor="#f0c0c0" align=center | {{angbr|gꞰh}}* ||  || 
<!-- Ju/hoan -->| bgcolor="#f0c0c0" align=center | ''gꞰh (dqh etc.)''<br />{{IPA|[ᶢꞰʱ ~ ᶢꞰˠ]}} ||  ||  ||  ||  || 
<!-- Xhosa -->| bgcolor="#f0c0c0" align=center | ''gq etc.''{{refn|Perhaps better described as [[slack voice]]. Tone-depressor effect.<ref>{{cite journal |last=Jessen |last2=Roux |year=2002 |title=Voice quality differences associated with stops and clicks in Xhosa |journal=Journal of Phonetics |volume=30 |issue=1 |pages=1–52 |doi=10.1006/jpho.2001.0150 }}</ref>|group=note}} || ||
|-
|rowspan=4|[[Nasal click consonant|Simple<br />nasal<br />click]]
| ''Voiceless''|| bgcolor="#c0c0f0" align=center | {{IPA|/ᵑ̊Ʞ/}}
<!-- !Xoo -->| bgcolor="#f0c0c0" align=center | {{angbr|nhꞰ}}*<br />{{IPA|[ŋ̊ᵑꞰ]}} ||  ||  ||  ||  ||  ||  ||  ||  ||  || ||
|-
| ''Voiced''|| bgcolor="#c0c0f0" align=center | {{IPA|/ᵑꞰ/}}
<!-- !Xoo -->| bgcolor="#f0c0c0" align=center | {{angbr|nꞰ}}* <br />{{IPA|[ŋ̈ᵑꞰ]}}
<!-- N/uu -->| bgcolor="#f0c0c0" align=center | {{angbr|ᵑꞰ}}
<!-- =Hoan -->| bgcolor="#f0c0c0" align=center | {{IPA|[ᵑꞰ]}}
<!-- Ju/hoan -->| bgcolor="#f0c0c0" align=center | ''nꞰ (nq etc.)''
<!-- Korana -->| bgcolor="#f0c0c0" align=center | ''Ʞn''
<!-- G/ui -->| bgcolor="#f0c0c0" align=center | {{angbr|ŋꞰ}}
<!-- Sandawe -->| bgcolor="#f0c0c0" align=center | ''nq etc.''
<!-- Hadza -->| bgcolor="#f0c0c0" align=center | ''nq etc. (nꞰ)''
<!-- Dahalo -->| bgcolor="#f0c0c0" align=center | {{IPA|/ᵑǀ/}}
<!-- Xhosa -->| bgcolor="#f0c0c0" align=center | ''nq etc.''
<!-- Yeyi -->| bgcolor="#f0c0c0" align=center | {{angbr|ŋꞰ}}
<!-- Damin -->| bgcolor="#f0c0c0" align=center | {{angbr|Nǃ}}
|-
| ''(Delayed) aspiration<br />(prenasalised between vowels)''|| bgcolor="#c0c0f0" align=center | {{IPA|/ᵑ̊Ʞʰʱ/}}
<!-- !Xoo -->| bgcolor="#f0c0c0" align=center | {{angbr|Ʞhh}}<br />{{IPA|[ŋ̊↓Ʞh]}}
<!-- N/uu -->| bgcolor="#f0c0c0" align=center | {{angbr|ᵑ̊Ʞʰ}}
<!-- =Hoan -->| bgcolor="#f0c0c0" align=center | {{IPA|[ᵑ̊Ʞʱ ~ ŋᵑ̊Ʞʱ]}}
<!-- Ju/hoan -->| bgcolor="#f0c0c0" align=center | ''Ʞʼh (qʼh etc.)''
<!-- Korana -->| bgcolor="#f0c0c0" align=center | ''Ʞh''
<!-- G/ui -->| bgcolor="#f0c0c0" align=center | {{angbr|ŋꞰh}} ||  ||  ||  ||  || ||
|-
| ''Breathy-voiced''|| bgcolor="#c0c0f0" align=center | {{IPA|/ᵑꞰʱ/}}
<!-- !Xoo -->| bgcolor="#f0c0c0" align=center | {{angbr|nꞰhh}} ||  || 
<!-- Ju/hoan -->| bgcolor="#f0c0c0" align=center | ''nꞰh (nqh etc.)'' ||  ||  ||  ||  || 
<!-- Xhosa -->| bgcolor="#f0c0c0" align=center | ''ngq etc.''<ref group=note>Tone-depressor effect. Sometimes a prenasalized click with a short, voiced oral occlusion, but usually without.</ref> || ||
|-
| colspan=2| ''Preglottalised nasal click''|| bgcolor="#c0c0f0" align=center | {{IPA|/ˀᵑꞰ/}} <!--Not placed under glottalized because the lingual airstream is not glottalized-->
<!-- !Xoo -->| bgcolor="#f0c0c0" align=center | {{angbr|ʼnꞰ}}*  || 
<!-- =Hoan -->| bgcolor="#f0c0c0" align=center | {{IPA|[ʔᵑꞰ]}} || align=center | (in Ekoka) ||  ||  ||  ||  ||  ||  || ||
|-
|rowspan=4|[[Glottalised click|Glottalised<br />click]]
| ''Oral / velar ejective'' || bgcolor="#c0c0f0" align=center | {{IPA|/ᵏꞰʼ/}}
<!-- !Xoo -->| bgcolor="#f0c0c0" align=center | {{angbr|Ʞʼ}}* || || || || |
<!-- G/ui -->| bgcolor="#f0c0c0" align=center | {{angbr|kꞰʼ}} || || || ||
<!-- Yeyi -->| bgcolor="#f0c0c0" align=center | {{angbr|Ʞʼ}} ||
|-
| ''Creaky-voiced oral'' || bgcolor="#c0c0f0" align=center | {{IPA|/ᶢꞰʼ/}}
<!-- !Xoo -->| bgcolor="#f0c0c0" align=center | {{angbr|gꞰʼ}}* ||  ||  ||  ||  ||  ||  ||  ||  ||  || ||
|-
| ''Nasal (silent initially,<br />prenasalised after vowels)''|| bgcolor="#c0c0f0" align=center | {{IPA|/ᵑ̊Ʞˀ/}}
<!-- !Xoo -->| bgcolor="#f0c0c0" align=center | {{angbr|Ʞʼʼ}}
<!-- N/uu -->| bgcolor="#f0c0c0" align=center | {{angbr|ᵑ̊Ʞˀ}}
<!-- =Hoan -->| bgcolor="#f0c0c0" align=center | {{IPA|[Ʞˀ ~ ŋˀꞰ]}}
<!-- Ju/hoan -->| bgcolor="#f0c0c0" align=center | ''Ʞʼ (qʼ etc.)''<br /><small>(w/ nasal vowels)</small>
<!-- Korana -->| bgcolor="#f0c0c0" align=center | ''Ʞ''
<!-- G/ui -->| bgcolor="#f0c0c0" align=center | {{angbr|kꞰʔ}} ({{IPA|ŋ̊Ʞʔ}})
<!-- Sandawe -->| bgcolor="#f0c0c0" align=center | ''qʼ etc.''<br />{{IPA|[Ʞˀʔ}} ~ {{IPA|ŋʔꞰˀ]}}
<!-- Hadza -->| bgcolor="#f0c0c0" align=center | ''qq etc.''<br />''(Ʞʼ ~ nꞰʼ)''
<!-- Dahalo -->| bgcolor="#f0c0c0" align=center | {{IPA|/ᵑǀˀ/}}
<!-- Xhosa -->| bgcolor="#f0c0c0" align=center | ''nkq etc.'' ?<ref>According to {{harvtxt|Nurse|Philippson|2003|p=616}}. This is typically transcribed as a prenasalized click, and is not included in Miller.</ref>
<!-- Yeyi -->| bgcolor="#f0c0c0" align=center | {{angbr|ŋꞰʼ}} ||
|-
| ''Nasal (prenasalised initially) ''|| bgcolor="#c0c0f0" align=center | {{IPA|/ᵑꞰˀ/}}
<!-- !Xoo -->| bgcolor="#f0c0c0" align=center | {{angbr|nꞰʼʼ}} ||  ||  ||  ||  ||  ||  ||  ||  ||  || ||
|-
|rowspan=6 bgcolor="#f2f2f2" |[[Pulmonic-contour click consonant|Pulmonic<br />contour]]
| bgcolor="#f2f2f2" |''Tenuis stop''|| bgcolor="#c0c0f0" align=center | {{IPA|/Ʞ͡q/}}
<!-- !Xoo -->| bgcolor="#f0c0c0" align=center | {{angbr|Ʞq}}
<!-- N/uu -->| bgcolor="#f0c0c0" align=center | {{angbr|Ʞq}}
<!-- =Hoan -->| bgcolor="#f0c0c0" align=center | {{IPA|[Ʞq]}}
!  || 
<!-- G/ui -->|  bgcolor="#f0c0c0" align=center | {{angbr|qꞰ}}
!  ||  ||  ||  || ||
|-
| bgcolor="#f2f2f2" |''Voiced (and prenasalised)''|| bgcolor="#c0c0f0" align=center | {{IPA|/ᶢꞰ͡ɢ/}}
<!-- !Xoo -->| bgcolor="#f0c0c0" align=center | {{angbr|gꞰq}}<br />{{IPA|[ᶰꞰɢ ~ Ʞɢ]}}
<!-- N/uu -->| bgcolor="#f0c0c0" align=center | {{IPA|[Ʞɢ]}}<ref group=note>not prenasalized</ref>
<!-- =Hoan -->| bgcolor="#f0c0c0" align=center | ({{IPA|[ᶰꞰɢ]}})<ref group=note>perhaps borrowed from Gǀui</ref>
!  || 
<!-- G/ui -->| bgcolor="#f0c0c0" align=center | {{angbr|ɢꞰ}}<br />{{IPA|[ᶰꞰɢ]}}
!  ||  ||  ||  || ||
|-
| bgcolor="#f2f2f2" |''Aspirated stop''|| bgcolor="#c0c0f0" align=center | {{IPA|/Ʞ͡qʰ/}}
<!-- !Xoo -->| bgcolor="#f0c0c0" align=center | {{angbr|Ʞqh}}
<!-- N/uu -->| bgcolor="#f0c0c0" align=center | {{angbr|Ʞqʰ}}
<!-- =Hoan -->| bgcolor="#f0c0c0" align=center | {{IPA|[Ʞqʰ]}}
!  || 
<!-- G/ui -->|  bgcolor="#f0c0c0" align=center | {{angbr|qꞰh}}
!  ||  ||  ||  || ||
|-
| bgcolor="#f2f2f2" |''Breathy-voiced ''|| bgcolor="#c0c0f0" align=center | {{IPA|/ᶢꞰ͡ɢʱ/}}
<!-- !Xoo -->| bgcolor="#f0c0c0" align=center | {{angbr|gꞰqh}}
!  ||  ||  ||  ||  ||  ||  ||  ||  || ||
|-
| bgcolor="#f2f2f2" |''Voiceless fricative ''|| bgcolor="#c0c0f0" align=center | {{IPA|/ᵏꞰ͡χ/}}
<!-- !Xoo -->| bgcolor="#f0c0c0" align=center | {{angbr|Ʞx}}
<!-- N/uu -->| bgcolor="#f0c0c0" align=center | {{angbr|Ʞχ}}
<!-- =Hoan -->| bgcolor="#f0c0c0" align=center | {{IPA|[Ʞq͡χ]}}
<!-- Ju/hoan -->| bgcolor="#f0c0c0" align=center | ''Ʞx (qg etc.)''
!
<!-- G/ui -->|  bgcolor="#f0c0c0" align=center | {{angbr|qꞰχ}}
!  ||  ||  || 
<!-- Yeyi -->| bgcolor="#f0c0c0" align=center | {{angbr|Ʞx}} (?)
!
|-
| bgcolor="#f2f2f2" |''Voiced fricative (prenasalised) ''|| bgcolor="#c0c0f0" align=center | {{IPA|/ᶢꞰ͡ʁ/}}
<!-- !Xoo -->| bgcolor="#f0c0c0" align=center | {{angbr|gꞰx}}<br />{{IPA|[ᶢꞰ͡χ ~ ɴᶢꞰ͡ʁ]}}
!  || 
<!-- Ju/hoan -->| bgcolor="#f0c0c0" align=center | ''gꞰx (dqg etc.)''
!  ||  ||  ||  ||  ||  ||  ||
|-
|rowspan=5 bgcolor="#f2f2f2" |[[Ejective-contour click consonant|Ejective<br />contour]]
| bgcolor="#f2f2f2" |''Ejective stop''|| bgcolor="#c0c0f0" align=center | {{IPA|/Ʞ͡qʼ/}}
<!-- !Xoo -->| bgcolor="#f0c0c0" align=center | {{angbr|Ʞqʼ}}
<!-- N/uu -->| bgcolor="#f0c0c0" align=center | {{IPA|[Ʞqʼ]}}
<!-- ǂHoan -->| bgcolor="#f0c0c0" align=center | {{IPA|[Ʞqʼ]}}
!  || 
<!-- G/ui -->| bgcolor="#f0c0c0" align=center | {{angbr|qꞰʼ}}
!  ||  ||  ||  || ||
|-
| bgcolor="#f2f2f2" |''Voiced ejective stop'' || bgcolor="#c0c0f0" align=center | {{IPA|/ᶢꞰ͡qʼ/}}
<!-- !Xoo -->| bgcolor="#f0c0c0" align=center | {{angbr|gꞰqʼ}}
!  ||  ||  ||  ||  ||  ||  ||  ||  || ||
|-
| bgcolor="#f2f2f2" |''Ejective fricative''|| bgcolor="#c0c0f0" align=center | {{IPA|/Ʞ͡χʼ/}}
!
<!-- N/uu -->| bgcolor="#f0c0c0" align=center | {{angbr|Ʞχʼ}}
<!-- ǂHoan -->| bgcolor="#f0c0c0" align=center | {{IPA|[Ʞq͡χʼ]}}
!
<!-- Korana -->| bgcolor="#f0c0c0" align=center rowspan=2 | ''Ʞkhʼ''
! ||  ||  ||  || 
<!-- Yeyi -->| bgcolor="#f0c0c0" align=center | {{angbr|Ʞqʼ}}<!--affricated per Miller-->
!
|-
| bgcolor="#f2f2f2" |''Heterorganic affricate /<br /> epiglottalised''|| bgcolor="#c0c0f0" align=center | {{IPA|/Ʞ͡kxʼ/}}
<!-- !Xoo -->| bgcolor="#f0c0c0" align=center | {{angbr|Ʞqxʼ}}
!  || 
<!-- Ju/hoan -->| bgcolor="#f0c0c0" align=center | ''Ʞk (qgʼ etc.)''<br />{{IPA|[Ʞᵸ]}}
<!-- G/ui -->| bgcolor="#f0c0c0" align=center | {{angbr|qꞰχʼ}}
!  ||  ||  ||  ||  ||
|-
| bgcolor="#f2f2f2" |''Voiced heterorganic <br />affricate / epiglottalised''|| bgcolor="#c0c0f0" align=center | {{IPA|/ᶢꞰ͡kxʼ/}}
<!-- !Xoo -->| bgcolor="#f0c0c0" align=center | {{angbr|gꞰqxʼ}}
!  || 
<!-- Ju/hoan -->| bgcolor="#f0c0c0" align=center | ''gꞰk (dqgʼ etc.)''<br />{{IPA|[ᶢꞰˤ]}}
!  ||  ||  ||  ||  ||  ||  ||
|-
| Egressive<ref group=note>Not technically a click, but the only other attested sound with a lingual airstream mechanism.</ref> || ''(Voiceless "spurt"; labial only)'' || bgcolor="#c0c0f0" align=center | {{IPA|/ʘ↑/}}
|  ||  ||  ||  ||  ||  ||  ||  ||  ||  || 
<!-- Damin -->| bgcolor="#f0c0c0" align=center | {{angbr|pʼ}}
|-
! colspan=2 |  || IPA || Taa || Nǁng || ǂʼAmkoe || Juǀʼhoan || Korana || Gǀui || Sandawe || Hadza || Dahalo || Xhosa || Yeyi || Damin
|}
</div>
Yeyi also has prenasalised {{IPA|/ŋᶢꞰ/}}. The original researchers believe that {{IPA|[Ʞʰ]}} and {{IPA|[Ʞχ]}} are allophones.

A DoBeS (2008) study of the Western ǃXoo dialect of Taa found several new manners: creaky voiced (the voiced equivalent of glottalised oral), breathy-voiced nasal, prenasalised glottalised (the voiced equivalent of glottalised) and a (pre)voiced ejective. These extra voiced clicks reflect Western ǃXoo morphology, where many nouns form their plural by voicing their initial consonant. DoBeS analyses most Taa clicks as clusters, leaving nine basic manners (marked with asterisks in the table). This comes close to Miller's distinction between simple and contour clicks, shaded light and medium grey in the table.

==Phonotactics==
Languages of the southern African Khoisan families only permit clicks at the beginning of a word root. However, they also restrict other classes of consonant, such as [[ejective consonant|ejectives]] and [[affricate]]s, to root-initial position. The Bantu languages, Hadza and Sandawe allow clicks within roots.

In some languages, all click consonants within known roots are the same phoneme, as in Hadza ''cikiringcingca'' {{IPA|/ǀikiɺiN.ǀiN.ǀa/}} 'pinkie finger', which has three [[tenuis dental click]]s. Other languages are known to have the occasional root with different clicks, as in Xhosa ''ugqwanxa'' {{IPA|/uᶢ̊ǃʱʷaᵑǁa/}} '[[Olea capensis|black ironwood]]', which has a slack-[[voiced alveolar click]] and a [[nasal lateral click]].

No natural language allows clicks at the ends of syllables or words, but then no languages with clicks allows many consonants at all in those positions. Similarly, clicks are not found in underlying consonant clusters apart from /Cw/ (and, depending on the analysis, /Cχ/), as languages with clicks do not have other consonant clusters than that. Due to vowel [[elision]], however, there are cases where clicks are pronounced in cross-linguistically common types of consonant clusters, such as Xhosa {{IPA|[sᵑǃɔɓilɛ]}} ''Snqobile'', from ''Sinqobile'' (a name), and {{IPA|[isǁʰɔsa]}} ''isXhosa'', from ''isiXhosa'' (the Xhosa language).<ref>{{cite book |first=William |last=Bennett |year=2020 |chapter=Click Phonology |editor-first=Bonny |editor-last=Sands |title=Click Consonants |publisher=Brill |pages=115–116 }}</ref>

Like other articulatorily complex consonants, clicks tend to be found in [[lexical words]] rather than in [[grammatical word]]s, but this is only a tendency. In [[Nǁng language|Nǁng]], for example, there are two sets of [[personal pronoun]]s, a full one without clicks and a partial set with clicks (''ńg'' 'I', ''á'' 'thou', ''í'' 'we all', ''ú'' 'you', vs. ''nǀǹg'' 'I', ''gǀà'' 'thou', ''gǀì'' 'we all', ''gǀù'' 'you'), as well as other grammatical words with clicks such as ''ǁu'' 'not' and ''nǀa'' 'with, and'.

===The back-vowel constraint===
[[Image:Clicks and the BVC.svg|thumb|The shape of the tongue in Nama when articulating an alveolar click (blue) and a palatal click (red) [throat to the right]. The articulation of the vowel {{IPA|[i]}} is slightly forward of the red line, with its peak coinciding with the dip of the blue line.]]
In several languages, including [[Nama language|Nama]] and [[Juǀʼhoan dialect|Juǀʼhoan]], the alveolar click types {{IPA|[ǃ]}} and {{IPA|[ǁ]}} only occur, or preferentially occur, before [[back vowel]]s, whereas the dental and palatal clicks occur before any vowel. The effect is most noticeable with the high front vowel {{IPA|[i]}}. In Nama, for example, the diphthong {{IPA|[əi]}} is common but {{IPA|[i]}} is rare after alveolar clicks, whereas the opposite is true after dental and palatal clicks. This is a common effect of [[uvular consonant|uvular]] or uvularised consonants on vowels in both click and non-click languages. In [[Taa language|Taa]], for example, the back-vowel constraint is triggered by both alveolar clicks and uvular stops, but not by palatal clicks or velar stops: sequences such as {{IPA|*/ǃi/}} and {{IPA|*/qi/}} are rare to non-existent, whereas sequences such as {{IPA|/ǂi/}} and {{IPA|/ki/}} are common. The back-vowel constraint is also triggered by labial clicks, though not by labial stops. Clicks subject to this constraint involve a sharp [[retracted tongue root|retraction]] of the tongue during release.

{|class="wikitable"
! !!Abrupt <br />release!!Noisy <br />release
|-
|ballistic tongue retraction<br />& back-vowel constraint
|align=center|{{IPA|ǃ}}||align=center|{{IPA|ǁ, ʘ}}
|-
|no retraction, no constraint
|align=center|{{IPA|ǂ}}||align=center|{{IPA|ǀ}}
|}

Miller and colleagues (2003) used [[ultrasound imaging]] to show that the rear articulation of the alveolar clicks ({{IPA|[ǃ]}}) in Nama is substantially different from that of palatal and dental clicks. Specifically, the shape of the body of the tongue in palatal clicks is very similar to that of the vowel {{IPA|[i]}}, and involves the same tongue muscles, so that sequences such as {{IPA|[ǂi]}} involved a simple and quick transition. The rear articulation of the alveolar clicks, however, is several centimetres further back, and involves a different set of muscles in the uvular region. The part of the tongue required to approach the palate for the vowel {{IPA|[i]}} is deeply retracted in {{IPA|[ǃ]}}, as it lies at the bottom of the air pocket used to create the vacuum required for click airstream. This makes the transition required for {{IPA|[ǃi]}} much more complex and the timing more difficult than the shallower and more forward tongue position of the palatal clicks. Consequently, {{IPA|[ǃi]}} takes 50 [[millisecond|ms]] longer to pronounce than {{IPA|[ǂi]}}, the same amount of time required to pronounce {{IPA|[ǃəi]}}.

Languages do not all behave alike. In [[Nǁng language|Nǀuu]], the simple clicks {{IPA|/ʘ, ǃ, ǁ/}} trigger the {{IPA|[əi]}} and {{IPA|[æ]}} allophones of {{IPA|/i/}} and {{IPA|/e/}}, whereas {{IPA|/ǀ, ǂ/}} do not. All of the affricated contour clicks, such as {{IPA|/ǂ͡χ/}}, do as well, as do the uvular stops {{IPA|/q, χ/}}. However, the occlusive contour clicks pattern like the simple clicks, and {{IPA|/ǂ͡q/}} does not trigger the back-vowel constraint. This is because they involve tongue-root raising rather than [[Advanced and retracted tongue root|tongue-root retraction]] in the uvular-pharyngeal region. However, in [[Gǀwi dialect|Gǀwi]], which is otherwise largely similar, both {{IPA|/ǂ͡q/}} and {{IPA|/ǂ͡χ/}} trigger the back-vowel constraint (Miller 2009).

==Click genesis and click loss==
One genetic study concluded that clicks, which occur in the languages of the genetically divergent populations Hadza and !Kung, may be an ancient element of human language.<ref>{{cite journal |last1=Tishkoff |first1=S. A. |last2=Gonder |first2=M. K. |last3=Henn |first3=B. M. |last4=Mortensen |first4=H. |last5=Knight |first5=A. |last6=Gignoux |first6=C. |last7=Fernandopulle |first7=N. |display-authors=1 |year=2007 |title=History of click-speaking populations of Africa inferred from mtDNA and Y chromosome genetic variation |journal=Molecular Biology and Evolution |volume=24 |issue=10 |pages=2180–95 |doi=10.1093/molbev/msm155 |pmid=17656633 |doi-access=free }}</ref> However, this conclusion relies on several dubious assumptions (see [[Hadza language]]), and most linguists{{citation needed|date=June 2019}} assume that clicks, being quite complex consonants, arose relatively late in human history. How they arose is not known, but it is generally assumed that they developed from sequences of non-click consonants, as they are found allophonically for [[doubly articulated consonant]]s in West Africa,{{sfn|Ladefoged|1968}} for {{IPA|/tk/}} sequences that overlap at word boundaries in German,<ref name=germ /> and for the sequence {{IPA|/mw/}} in [[Ndau language|Ndau]] and [[Tonga language (Zambia)|Tonga]].<ref group=note>Here the labial {{IPA|[m]}} may have assimilated to the velar place of the {{IPA|[w]}}, as {{IPA|[m͡ŋw]}}, with the release of the labial before the velar later generating a click {{IPA|[ᵐʘw]}}</ref> Such developments have also been posited in historical reconstruction. For example, the [[Sandawe language|Sandawe]] word for 'horn', {{IPA|/tɬana/}}, with a lateral affricate, may be a cognate with the root {{IPA|/ᵑǁaː/}} found throughout the [[Khoe languages|Khoe family]], which has a lateral click. This and other words suggests that at least some Khoe clicks may have formed from consonant clusters when the first vowel of a word was lost; in this instance *{{IPA|[tɬana]}} > *{{IPA|[tɬna]}} > {{IPA|[ǁŋa] ~ [ᵑǁa]}}.

On the other side of the equation, several non-endangered languages in vigorous use demonstrate click loss. For example, the [[Khoe languages|East Kalahari languages]] have lost clicks from a large percentage of their vocabulary, presumably due to [[Bantu languages|Bantu]] influence. As a rule, a click is replaced by a consonant with close to the [[manner of articulation]] of the click and the [[place of articulation]] of the forward release: alveolar click releases (the {{IPA|[ǃ]}} family) tend to mutate into a velar stop or affricate, such as {{IPA|[k], [ɡ], [ŋ], [k͡x]}}; palatal clicks (the {{IPA|[ǂ]}} family) tend to mutate into a palatal stop such as {{IPA|[c], [{{thin space}}ɟ], [{{thin space}}ɲ], [cʼ]}}, or a post-alveolar affricate {{IPA|[tʃ], [dʒ]}}; and dental clicks (the {{IPA|[ǀ]}} family) tend to mutate into an alveolar affricate {{IPA|[ts]}}.{{Citation needed|date=April 2011}}

==Difficulty==
Clicks are often presented as difficult sounds to articulate within words. However, children acquire them readily; a two-year-old, for example, may be able to pronounce a word with a lateral click {{IPA|[ǁ]}} with no problem, but still be unable to pronounce {{IPA|[s]}}.<ref>{{cite conference |first=Kirk |last=Miller |date=2009 |title=Highlights of Hadza fieldwork |url=https://www.lsadc.org/files/2009_Annual_Meeting_Handbook.pdf#page=171 |conference=LSA |location=San Francisco }}</ref> [[Lucy Lloyd]] reported that after long contact with the Khoi and San, it was difficult for her to refrain from using clicks when speaking English.<ref>{{Harvnb|Beach|1938|p=269}}.</ref>

==See also==
{{Div col||colwidth=20em}}
* [[Bilabial click]]s
* [[Dental click]]s
* [[Alveolar click]]s
* [[Fricated alveolar click]]s
* [[Lateral click]]s
* [[Retroflex click]]s
* [[Palatal click]]s
* [[Back-released click]]
* [[Nasal click]]s
* [[Glottalised click]]s
* [[Pulmonic-contour click]]s
* [[Ejective-contour click]]s
* [[Click letter]]s
* [[List of phonetics topics]]
* [[Sublaminal lower alveolar click]]
* [[Clicking noise]]
* [[The Click Song]]{{div col end}}

==Notes==
{{Reflist|group=note}}

==References==
{{Reflist}}

==Bibliography==
* {{cite book|last=Ladefoged|first=Peter|year=1968|title=A phonetic study of West African languages: An auditory-instrumental survey|publisher=Cambridge University Press |edition= 2nd|isbn=0-521-06963-7}}
* {{SOWL}}
* {{cite book |first=Amanda |last=Miller |first2=Levi |last2=Namaseb |first3=Khalil |last3=Iskarous |year=2003 |title=Tongue Body constriction differences in click types }}
* {{cite book |first=Amanda |last=Miller |year=2011 |chapter=The Representation of Clicks |editor-last=Oostendorp |title=The Blackwell Companion to Phonology }}
* {{cite journal |last=Traill |first=Anthony |first2=Rainer |last2=Vossen |year=1997 |title=Sound change in the Khoisan languages: new data on click loss and click replacement |journal=J African Languages and Linguistics |volume=18 |issue=1 |pages=21–56 |doi=10.1515/jall.1997.18.1.21 }}

==External links==
* [http://homepage.ntu.edu.tw/~karchung/Phonetics%20II%20page%20four.htm Collection of click-language links and audio samples].
* [http://www.ling.su.se/fon/perilus/2003_21.pdf Hartmut Traunmüller (2003) "Clicks and the idea of a human protolanguage", ''Phonum 9:'' 1 – 4 (Umeå University, Dept. of Philosophy and Linguistics)] {{Webarchive|url=https://web.archive.org/web/20120722123112/http://www2.ling.su.se/fon/perilus/2003_21.pdf |date=22 July 2012 }}
* [http://esciencenews.com/articles/2009/07/15/classifying.clicks Classifying clicks]

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