Mitchell F. Chan sent us a link to this amazing music-driven kinetic sculpture piece. He explains how it works:
The project on display in the video is titled “Visions of the Amen” by Mitchell F. Chan. It’s being brought to life by the voice of talented young soprano Ashleigh Semkiw. It’s a kinetic sculpture in which strings, weighed down on one end by brass bars and attached at the other end to motors, spin at various speeds to sweep out those ghostly sine-wave forms, and pull up and down on the brass rods. The resultant visual effect, overall, looks something like 16 brass rods dancing, bobbing up and down in a forest of ghostly columns.
Each string in the arrangement is activated by a different note, and spins with a velocity dependent on the volume of that note. So each song and unique delivery creates a different ballet. The microphone feeds into a software that I wrote in Processing, which does some pitch and volume analysis, and then exports PWM values for all the motors via serial protocol to a set of microcontrollers. I originally set it up with Arduinos, but I found that for addressing multiple controllers, the protocol was simpler using the new ArtBus controller being developed at the School of the Art Institute of Chicago. (http://www.artbusinterface.com/SAIC)