The voiced retroflex implosive is a type of consonantal sound. Wadiyara Koli phonemically distinguishes it from the alveolar /ɗ/. Sindhi has an implosive that varies between dental and retroflex articulation, while Oromo, Saraiki and Ngad'a have /ᶑ / but not /ɗ/.[1]
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 can be apical (pointed) or, in some fricatives, laminal (flat).
Its phonation is voiced, which means the vocal cords vibrate during the articulation.
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. Since it is voiced, the glottis is not completely closed, but allows a pulmonic airstream to escape through it.
^In Mangbai/ɗ/ may also be retroflex, but it appears to be a preglottalized [ʔ͡ɖ] rather than an implosive (Anonby 2008).
^Handbook of the International Phonetic Association, 1999, p. 166, 179.
^Kirk Miller & Michael Ashby, L2/20-252R Unicode request for IPA modifier-letters (a), pulmonic
^Shackle, Christopher (1976). The Siraiki language of central Pakistan : a reference grammar. London: School of Oriental and African Studies. pp. 22–23.
