The world we live in is full of noise. It is difficult to perceive it because it is so pervasive-there are few silences that are not given shape by the hum of the computer or the faraway roar of traffic or the steady whisper of the lighting. Silence, like many other aspects of preindustrial human experience, is now among the privileges reserved for the very wealthy. They and a few others have the necessary frame of reference to understand how pervasive, and how definitive, noise is to the world we have created. The sound of the contemporary world is absolutely unprecedented in human history.