Nasal retroflex click

The retroflex nasal click is a rare click consonant. In practical orthography, an ad hoc symbol ⟨‼⟩ is used for the retroflex clicks; a nasal click with a velar rear articulation is ⟨ŋ͡‼⟩ or ⟨ŋ͜‼⟩, commonly abbreviated to ⟨ŋ‼⟩, ⟨ᵑ‼⟩ or ⟨‼̃⟩. The implicit symbol in the International Phonetic Alphabet is ⟨ŋ͡𝼊⟩ or ⟨ŋ͜𝼊⟩, abbreviated ⟨ŋ𝼊⟩, ⟨ᵑ𝼊⟩ or ⟨𝼊̃⟩. Linguists who prefer the old IPA letters use the analogous Doke convention of ⟨ŋ͡ψ⟩ or ⟨ŋ͜ψ⟩, abbreviated ⟨ŋψ⟩, ⟨ᵑψ⟩ or ⟨ψ̃⟩. For a click with a uvular rear articulation, the equivalents are ⟨ɴ͡‼, ɴ͜‼, ɴ‼, ᶰ‼⟩, ⟨ɴ͡𝼊, ɴ͜𝼊, ɴ𝼊, ᶰ𝼊⟩ and ⟨ɴ͡ψ, ɴ͜ψ, ɴψ, ᶰψ⟩. Sometimes the accompanying letter comes after the click letter, e.g. ⟨𝼊ŋ⟩ or ⟨𝼊ᵑ⟩; this may be a simple orthographic choice, or it may imply a difference in the relative timing of the releases.

Features
Features of the retroflex nasal click:

Occurrence
Retroflex nasal clicks are only attested from two languages, Central !Kung and Damin.

Glottalized alveolar nasal click
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.