Pendulum MusicPendulum Music is the name of a work by Steve Reich, involving suspended microphones and speakers, creating feedback tones.
Four or more microphones are suspended above the speakers by means of a cable and stand. The microphones are pulled back, switched on, and swung back and forth over the speaker. As the microphone nears the speaker, a feedback tone is created. The music created is then the result of the process of the swinging microphones.
Reich specifies the piece should continue until all the microphones are at rest over the speakers, each emitting a continuous tone. The microphone jacks are then to be pulled out simultaneously, cutting the sound off.