Some drones are lilting things that serve as background listening, as emotional cues, as gentle attempts at spatial reconfiguration. Others are dense constructs, enveloping environs that invite investigation, sonic mazes akin to virtual terrains, like the maps of RPGs and the plots of complex fictions. The latter descriptor applies to “Numinous,” from the Kiev, Ukraine”“based Dronny Darko. For a solid seven minutes it traffics in a thick, guttural, slow-motion howl. Its vibrant darkness is occasionally, mustily illuminated, giving hints at vocal intonations, distant noises, anxious activity. It’s a place with no answers to its inherent mystery — and you’ll find yourself visiting it repeatedly for the pleasure provided by their absence.