Soundwave Cancelation Question!!

[smoothbass12]

To all you music science geek people out there! So I have done quite a bit researching trying to understand soundwaves, soundwave cancelation, and all that fun music science stuff, and I haz a question!!!

So if soundwave cancelation is done by playing the opposite sound as the sound played (by changing it by 180 degrees or something like that that i still don't understand completely) and thus "fills" the vacancies of the vally of a sound wave, can you play a sound off sync by the the time of the wavelength along with the original sound and cancel each other out in live time? Like if you have a speaker playing a tone and then set up a second speaker playing the same tone, but start the second speaker at the precise delayed time that it would "fill" the vacancy of the the original wave, would it cancel the other out. So basically can a tone cancel itself out?

Sorry about the complexity, i probably need a picture to better illustrate... Thankyou to all you smart people who can answer this!

[T-Bird]

Hi.

Theoretically yes, and that's a great and easy way to blow up a stack of subwoofers in reality as well.

The active noise cancellation in aviation headsets works with that principle.

Regards
Sam

[Steve]

You mess around with cabs and speakers long enough and sooner or later you'll get one out of phase. The difference can be pretty impressive.

[Munjibunga]

Here's a pic of phase cancellation with subs separated different distances. It also shows the cancellation at different bass frequencies.

[smoothbass12]

Dang... I had no idea there was that much into it. Thats pretty interesting (as well as awesome).

[sonic assassin]

i was at a pool party one time where a buddy was running his laptop into a power amp and a couple mains he had laying around. just set them a few feet apart and turned it up. we (a bunch of audio engineering students) found that if you stood in one particular spot, there was some mild phase cancellation. certain frequencies, not entire signals.

similarly, we found that when playing halo 3, if 2 people fired a cannon at the same time, it would phase out.

also true when i program drums and try to make a flam. if they are too close, they try to cancel each other out. i REALLY need to get some left-hand/right-hand samples for this.

[lowfreq33]

In short the answer to your question is yes, but only if it's exactly the same sound ( like a sine wave) and is coming from the same speaker. Otherwise some frequencies will cancel out and others will be reinforced (get louder).