The labial–velar nasal is found in West and Central Africa and eastern New Guinea, as well as in certain contexts in Vietnamese.[1][2]
Features
Features of the voiced labial–velar nasal:
Its manner of articulation is occlusive, which means it is produced by obstructing airflow in the vocal tract. Because the consonant is also nasal, the blocked airflow is redirected through the nose.
Its place of articulation is labial–velar, which means it is simultaneously articulated with the lips and with the back part of the tongue (the dorsum) against the soft palate (the velum). The dorsal closure is made and released slightly before the labial closure, but they overlap for most of their duration.
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.
In the Banks Islands languages which have it, the phoneme /ŋ͡mʷ/ is written ⟨m̄⟩ in local orthographies, using a macron on the corresponding bilabial.
In other languages of Vanuatu further south (such as South Efate, or Lenakel), the same segment is spelled ⟨m̃⟩ with a combining tilde.