The IPA provides 5 click symbols: labial, dental, alveolar, palate-alveolar and lateral. These symbols specify the anterior release of these sounds. In order to indicate voicing the symbol for the voiced or voiceless velar plosive is added (clicks are essentially double articulations). Nasal clicks are transcribed by adding the symbol for the velar nasal.
The phonemic use of clicks is quite rare in languages of the world: they are restricted to languages in southern Africa. Clicks occur in all three groups of Khoisan language families and in the neighbouring Bantu languages which borrowed some of them (Zulu, Xhosa, Sotho, Ndebele). In addition to this there are three languages with clicks in East Africa (Hazda, Sandawe and Dahalo). It is generally assumed that clicks in the Bantu languages have been borrowed from Khoisan languages as a result of language contact.
The video adjacent is an X-ray recording of some of the Zulu clicks by a female native speaker who reads a short Zulu sentence 'Iqaqa lega umgwaqo namaqanda ezinkukhu aqhuma athi qhu' (A polecat crosses the road with eggs of chicken and they burst making a qhu sound).
Maddieson, I., Ladefoged, P., Sands, B. (1999). Clicks in East African Languages. In African Mosaic: Festschrift for J.A. Louw. Pretoria: University of South Africa Press. 59-91.
Wright, M. (2011). On clicks in English talk-in-interaction. Journal of the International Phonetic Association, 41/2, pp. 207-229.