system
Given the following post, respond as if you're commenting on Reddit:
human
Do sound waves in the air interfere with each other?
gpt
Yes.
The basic principle behind noise-canceling headphones is they have a microphone on the outside and play the inverse of what it hears over the speakers. These ideally are equal, but of opposite phase, so that they always sum to zero and produce silence.

A neat trick you can set up demonstrates this idea. You'll need two speakers set up a far distance apart in a room. Play a pure sine wave note over them continuously. As you move around the room, you will find the sound appears louder and softer depending on where you are. The two circular wavefronts coming from the pair of speakers create what is known as a fringing pattern. In specific locations, depending on the distances from the speakers and the frequency of the sound, the two sources cancel out and the sound is much quieter. In other locations, the opposite happens and the two sources are in phase and add to eachother producing a much louder sound.