Abstract: An exemplary retainer ring for a head of an acoustic drum can produce a visual display that allows an observer to visualize timing associated with percussive sound. An exemplary retainer ring includes a vertical wall disposed at a radius about a central axis and a laser diode module that includes a lens to emit visible radiation as a fan-beam. In such an exemplary retainer ring, the lens is positioned such that the fan-beam crosses the central axis and terminates as an arc in a groove in the vertical wall. When an object interrupts the fan-beam, the object reflects visible radiation of the fan-beam to thereby produce a visual display that allows an observer to visualize timing associated with percussive sound (e.g., sound produced by the object contacting a head of an acoustic drum). Various other exemplary arrangements, devices, systems, methods, etc., are also disclosed.

Abstract: An exemplary retainer ring for a head of an acoustic drum can produce a visual display that allows an observer to visualize timing associated with percussive sound. An exemplary retainer ring includes a vertical wall disposed at a radius about a central axis and a laser diode module that includes a lens to emit visible radiation as a fan-beam. In such an exemplary retainer ring, the lens is positioned such that the fan-beam crosses the central axis and terminates as an arc in a groove in the vertical wall. When an object interrupts the fan-beam, the object reflects visible radiation of the fan-beam to thereby produce a visual display that allows an observer to visualize timing associated with percussive sound (e.g., sound produced by the object contacting a head of an acoustic drum). Various other exemplary arrangements, devices, systems, methods, etc., are also disclosed.

Abstract: 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.

Abstract: 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.