|Voiceless alveolar implosive|
A voiceless retroflex implosive is a rare consonantal sound, used in some spoken languages. There is no official symbol in the International Phonetic Alphabet that represents this sound, but ⟨ᶑ̊⟩ or ⟨ʈʼ↓⟩ may be used, or the old convention ⟨⟩ (ƭ̢).
Features of the voiceless retroflex implosive:
- Its manner of articulation is occlusive, which means it is produced by obstructing airflow in the vocal tract. Since the consonant is also oral, with no nasal outlet, the airflow is blocked entirely, and the consonant is a plosive.
- 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 subapical articulation, the tongue contact can be apical (pointed) or laminal (flat).
- Its phonation is voiceless, which means it is produced without vibrations of the vocal cords.
- It is an oral consonant, which means air is allowed to escape through the mouth only.
- 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.
- The airstream mechanism is implosive (glottalic ingressive), which means it is produced by pulling air in by pumping the glottis downward. As it is voiceless, the glottis is completely closed, and there is no pulmonic airstream at all.
A rare and evidently unstable sound,  has been described from Oromo of Ethiopia.