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 (British spelling) or tsk! tsk! (American spelling) used to express disapproval or pity (IPA [ǀ]), the tchick! used to spur on a horse (IPA [ǁ]), and the clip-clop! sound children make with their tongue to imitate a horse trotting (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 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, 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. (Full article...)