The retroflex nasal click is a rare click consonant. There is no symbol for it in the International Phonetic Alphabet, but one can be derived with a diacritic, ⟨ǃ̃˞ ⟩ or ⟨ᵑǃ˞ ⟩. The Beach convention is ⟨ᵑ‼⟩, and this use used in practical orthography.
Features of the retroflex nasal click:
The airstream mechanism is lingual ingressive (also known as velaric ingressive), which means a pocket of air trapped between two closures is rarefied by a "sucking" action of the tongue, rather than being moved by the glottis or the lungs/diaphragm. The release of the forward closure produces the "click" sound. Voiced and nasal clicks have a simultaneous pulmonic egressive airstream.
Its place of articulation is retroflex, which prototypically means it is articulated subapical (with the tip of the tongue curled up), but more generally, it means that it is postalveolar without being palatalized. That is, besides the prototypical sub-apical articulation, the tongue contact can be apical (pointed) or laminal (flat).
Its phonation is voiced, which means the vocal cords vibrate during the articulation.
It is a nasal consonant, which means air is allowed to escape through the nose, either exclusively (nasal stops) or in addition to through the mouth.
It is a central consonant, which means it is produced by directing the airstream along the center of the tongue, rather than to the sides.
Retroflex nasal clicks are only attested from two languages, Central !Kung and Damin.
All Khoisan languages have glottalized nasal clicks. These are formed by closing the glottis so that the click is pronounced in silence; however, any preceding vowel will be nasalized.
