Clicks are speech sounds that occur as consonants in many languages of southern Africa, and in three languages of East Africa. Examples of these sounds familiar to English speakers are the ''tsk! tsk!'' (American spelling) or ''tut-tut'' (British spelling) 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.
Technically, clicks are obstruents articulated with two closures (points of contact) in the mouth, one forward and one at the back. The enclosed pocket of air is rarefied by a sucking action of the tongue (in technical terminology, clicks have a lingual ingressive airstream mechanism). The forward closure is then released,〔This is the case for all clicks that constitute consonants in words. Paralinguistically, however, there are other methods of making clicks: ''under'' the tongue and by releasing the rear occlusion first. See #Places of articulation.〕 producing what may be the loudest consonants in the language, although in some languages such as Hadza and Sandawe, clicks can be more subtle and may even be mistaken for ejectives.
==What clicks sound like==
Click consonants occur at five principal places of articulation. IPA represents a click by placing the assigned symbol for the place of click articulation adjacent to a symbol for a non-click sound at the rear place of articulation. The IPA symbols are used in writing most Khoisan languages, but Bantu languages such as Zulu typically use Latin , and for dental, lateral, and alveolar clicks respectively.
* The easiest clicks for English speakers are the dental clicks written with a single pipe, . They are all 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, and sometimes to call an animal, and is written ''tsk!'' in American English and ''tut!'' in British English.
* Next most familiar to English speakers are the lateral clicks written with a double pipe, . They are also squeaky sounds, though less sharp than , 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!''
* Then there are the labial clicks, written with a bull's eye, . These are lip-smacking sounds, but without the pursing of the lips found in a kiss.
The above clicks sound like affricates, in that they involve a lot of friction. The other two families are more abrupt sounds that do not have this friction.
* With the alveolar clicks, written with an exclamation mark, , 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. These sounds can be quite loud.
* Finally, the palatal clicks, , are made with a flat tongue, and are sharper popping sounds than the clicks, like sharply snapped fingers.
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』