Phase cancellation is an important concept in audio production and engineering. Phase cancellation is based on the frequency of a sound emitting source and the phase. In simpler terms this is the rate at which sound is coming at something and the amount of the sound coming. Cancellation has to do with combining sound to in effect cancel both sounds. If sound is construed as a wave, phase cancellation combines two opposite waves to cancel each other out. Phase cancellation can be intentional and by accident. If by accident it can lead to problems in audio such as when artists are not mic'd correctly. A common technique to overcome phase cancellation is to use the 3:1 rule and to use production equipment to filter or adjust for cancellation.
"Phase cancellation is when two or more audio wave forms clash with each other, resulting in deconstructive interference."