Hey guys, I have an average-man knowledge in physics so please simplify your question so anyone could understand :) I had no place for this so I'm writing it here in the general forum. I asked a friend of mine if you can supress sound waves entirely, so you won't hear a thing. to keep things short, he answered but I thought of something else: I thought of when you hear music with headphones for example and can't hear your surroundings. well, what if you did the same thing, only with sound at frequency that humans can't hear? you won't hear anything. I asked my friend, he told me that the sound from your surroundings aren't getting "canceled" - so it won't work, so I told him that if it's a wave, a stronger wave should completely runover a weaker wave, just like at the beach/sea. so we both don't know why it doesn't work. I'm hoping to find an answer here. What I tried: I'm a programmer so I built a quick program to generate those waves. I turned on the TV and played music in my headphones to make sure the volume is high enough not to hear anything from the TV. So I (turned the music off of course and) played a sound with a frequency that's out of the ear's range, and I really couldn't hear it but I did hear the TV (and so it failed). Could you guys explain to me please why it didn't work? (to be honest, I wasn't sure at all that it will work, but had to give it a shot. Thanks! EDIT: By the way, just to make things clear: my goal was not to hear the TV + nothing at all! the wave (which I can't hear) would "block" anything else, just like the music did.