# Is it possible to use “negative sound waves” to “cancel out” a sound to create silence?

I saw youtube videos that claimed to do this, although I'm quite certain the videos just excluded sound and lied.

However, I am wondering if the physics of this is actually possible - to create a completely negative sound wave that cancels the sound out to a flat line i.e. complete silence.

p.s. I am not referring to white noise, which prevents the sound from being heard by overriding it with a different sound (white noise). Rather, I am referring to making a sound be completely silent by generating the inverse, opposite, or "negative" sound wave.

• You can cancel sound in one location in space but not everywhere without the second signal that causes the destructive interference also coming from the same point in space as the source. – Brandon Enright Oct 25 '14 at 6:05
• Look up "noise cancelling headphones". – DanielSank Oct 25 '14 at 6:06
• by using destructive interference of waves it should be possible (at some locations/conditions) – Nikos M. Oct 25 '14 at 10:58

• so, when it comes to light, intensity doesn't matter? Is it possible to have a light cancelling torch for any given torch? – Saravanabalagi Ramachandran Dec 27 '16 at 13:22
• even in sound, we need to have the cancelling speaker right exactly at the source, so the intensity distributes so evenly, right? – Saravanabalagi Ramachandran Dec 27 '16 at 14:47