When using noise-canceling headphones, the unwanted sounds are canceled out by creating an opposing sound wave to the one you want to eliminate.

It means that when one sound wave is at its highest peak, the other is at its lowest, canceling each other out.

• The microphone on the earcup listens out for ambient noise.
• When the noise is registered, the microphone sends the frequency and amplitude of the incoming wave back to the noise-canceling circuitry.
• An out-of-phase sound is created, then fed into the headphone speakers...