Ok Remy, this time i'm on the fish!

Posted: Sun Jul 13, 2008 2:25 am

I know that if you have a sound and add its inverse wave (out-of-phase) the sound will cancel.

So here is the theoretical science experiment:

I live next to a heating and cooling building for the University, the building has these giant smoke stacks reaching out of the building straight up to the heavens.

When I go to sleep at night, I can hear a faint rumble of LF generated by these big pipes or by the building in general.

Is it possible to use phase cancellation to remove the rumble from my listening space (by that I mean pillow) by placing a mic a few inches above my face then putting the sound out of phase, then playing it through speakers on either side of my bed?

I'd always wondered if these ideas are feasible, in the sense of using the same method to make a busy highway silent for a residential neighborhood.

So lets stand by the water-cooler and explore the feasibility of this.

Posted: Sun Jul 13, 2008 6:55 am

Smoking fish before you sleep makes you wonder cool things.

You can cancel the noise out, but not with a microphone in front of your face.

And not without some seriously insane acoustics studies and some probably un-invented speaker system.

Every solid piece of the structure is what is resonating at that LF, You would need to phase cancel every wall, and without creating other reflections.

Man, my head pops thinking about the maths.

Pass the fillet.

Posted: Sun Jul 13, 2008 9:54 am

This ones for you Greener :

Cost-Effective Noise Masking Systems
http://www.rane.com/note116.html

Posted: Sun Jul 13, 2008 10:20 am

That stinks of something.
Maybe it's something my tiny mind can't comprehend.
Maybe it's because it's not written coherently.

Believe it when I see it.

Or more accurately, when I stop hearing it.

Posted: Sun Jul 13, 2008 1:24 pm

Just grow older by a few years and listen to black metal at 11, your LF hearing will go and you won't have to worry Smile

until then...uhhh...

Posted: Sun Jul 13, 2008 2:02 pm

yea, well, I think it's the difference between air borne and structure borne vibration, you can mask one...sorry, I should have waited for Ms. Remy...'scuse me Smile

Posted: Mon Jul 14, 2008 12:16 am

Speaking of masking, have a look at this:

http://www.flat-d.com/chairpadblack.html

Posted: Tue Jul 15, 2008 9:34 pm

Is it a reference to backwards masking?

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