In normal speech production the velum does not completely close off the pharyngeal passage to the nose, and the degree of velic opening is variable.

Larger ships try to maintain an average water draft when they are light (without cargo), in order to make a better sea crossing and reduce the effects of the wind (high centre of velic force).

Since the articulations involved are probably to a degree mutually exclusive (velic and pharyngeal), and since they seem to contribute similar auditory components (nasalization and "turbidity"), they are more likely to be allophones resulting from assimilation.

"Beatboxing," as it came to be known, includes laryngeal lowering and lingual retraction, labial approximation, velic raising (to seal the nasopharynx off from the oral vocal tract, of course) and rapid raising of the tongue dorsal.