Six series of pulmonic-contour clicks (as classified by the rear release) are attested. There are two manners of articulation (stop and fricative) and four voicing contrasts, each of which is found for each of the places of articulation (as classified by the front release) that clicks use. ;Linguo-pulmonic stops In linguo-pulmonic stops, the rear articulation is released into a
pulmonic stop. This may be tenuis, aspirated, voiced, or murmured (breathy-voiced). The modally voiced and breathy-voiced clicks tend to be
prenasalized in the various languages which use them, for reasons which are not clear. They tend to be written with a before or after the letter for the click, and with an afterward for the aspirated and breathy-voiced clicks. In IPA, using the
alveolar series as an example, the four attested series of linguo-pulmonic stops may be transcribed , , , , with the possibility of or to indicate the prenasalization. The breathy-voiced consonants of some languages such as
Juǀʼhoansi, including clicks, contain a voiceless interval and are sometimes written with mixed voicing. Miller (2003) attributes this to a larger glottal opening than is found in for example
Hindustani breathy-voiced consonants. ;Linguo-pulmonic affricates The rear articulation may also be released as a
fricative, one which may be either voiceless or voiced. Aspiration / breathy voice is not distinctive, as fricatives are not easily aspirated. However, because the forward articulation may be considered a stop, these are called
affricates rather than fricatives. There are two conventions for writing the frication: the English convention, with an , and the Afrikaans tradition, with a . Both are used in the orthographies of Khoisan languages. In Juǀ’hõa, for example, they are written voiceless and voiced , and in the old orthography and ; in Naro, they are (voiceless) , and in Khoekhoe . In the IPA, the two series of
linguo-pulmonic affricates may be written and , though with a cluster analysis they would be and . These clicks are affricates at the posterior place of articulation; they are independent of the
fricated alveolar clicks, which are affricates at their anterior place of articulation, a manner which does not affect the airstream. The fricated alveolar clicks may be lingual or linguo-pulmonic—that is, they may be affricates at both places of articulation, or at one. ==See also==