An exemplary device includes a first emitter to emit radiation from a first perspective substantially parallel to a head of a drum or other surface, a second emitter to emit radiation from a second perspective substantially parallel to the head of the drum or other surface, detectors to detect interruptions in the radiation from the first perspective as caused by an object; and detectors to detect interruptions in the radiation from the second perspective as caused by an object, wherein detected interruptions allow for one or more determinations (e.g., sounds, sound effects and control actions). Emitters optionally emit radiation as a fan-beam and detectors are optionally arranged along an arc. Various other exemplary arrangements, devices, systems, methods, etc., are also disclosed.