This Demonstration simulates the mechanism of noise cancellation in headphones. The graph is divided into three parts. The left side shows a superposition of two distinct sound waves, with a dashed line designating the resultant wave. This superposition is translated to the center, where a phase shift is introduced. This is what produces noise cancellation by destructive interference. The resultant waveform is shown by the dashed curve in the center, as well as by the wave on the right.