Noise cancellation on a computer?

[Syborg1211]

They have it on headphones... why not have a speaker on or inside the case that sends out sounds to cancel the noise of the fans? Wouldn't that be awesome?

 

[MercenaryForHire]

Noise + Noise = Noise.

- M4H

 

[PowerMacG5]

Originally posted by: MercenaryForHire
Noise + Noise = Noise. - M4H

Not true. Take a high school physics course. Sound waves cancel out when crest meets trough, and trough meets crest (when the sound waves are same frequency and amplitude and wavelength). Noise + Noise does not necessarily = Noise. Noice cancelling headphones work on a similar principle. Send out sound waves that are a half wavelength off.

 

[MercenaryForHire]

Originally posted by: KraziKid
Not true. Take a high school physics course. Sound waves cancel out when crest meets trough, and trough meets crest (when the sound waves are same frequency and amplitude and wavelength). Noise + Noise does not necessarily = Noise. Noice cancelling headphones work on a similar principle. Send out sound waves that are a half wavelength off.

I'd think if it was as easy as is proposed, it would have been done already.

So you're saying if I take two sonic booms from passing F-117A Stealth Bombers and position them such that they cancel each other out, I won't get blown eardrums? 😛

- M4H

 

[PowerMacG5]

Originally posted by: MercenaryForHire

Originally posted by: KraziKid Not true. Take a high school physics course. Sound waves cancel out when crest meets trough, and trough meets crest (when the sound waves are same frequency and amplitude and wavelength). Noise + Noise does not necessarily = Noise. Noice cancelling headphones work on a similar principle. Send out sound waves that are a half wavelength off.

I'd think if it was as easy as is proposed, it would have been done already. So you're saying if I take two sonic booms from passing F-117A Stealth Bombers and position them such that they cancel each other out, I won't get blown eardrums? 😛 - M4H

The only problem is, the F117 cannot break the sound barrier (Max Speed Mach 0.9 proof). So, there is no sonic boom 😛. But, in theory, two sonic booms created by F-22's 😛 created so that crest meets with trough and trough meets with crest could conceivably be silent.

 

[TheBDB]

It probably hasn't been done due to costs and a lack of demand.

 

[0roo0roo]

tech requires headphones

 

[sharkeeper]

It is possible but impractical for a typical pc application because the noise isn't of a magnitude where it presents a hazard and the design and deployment of such apparatus is prohibitively expensive. (ICACS)

-DAK-

 

[43st]

It can be done and it's a great idea. At this point the tech is a wee pit expensive. Doubtful than an average Joe computer user can afford an active cancellation system (and a small equipment rack to house it). You could build one using pro audio components but it would probably cost you four thousand or more.

If you were more into fiddling around with electronics you could make one for a lot cheaper.

 

[43st]

A bit more...

My company installs noise cancellation systems on occasion (not often). We have to treat the entire room though, not just the source of the noise. This is what makes it really impractical for a consumer type system. I'm sure a DSP could be programmed to estimate a wave form but ultimately it wouldn't be effective, certainly not worth the costs involved.

Here's a link that talks about some different methods being used today. Pretty cool stuff.

 

[Jeff7]

Originally posted by: KraziKid

Originally posted by: MercenaryForHire

Originally posted by: KraziKid Not true. Take a high school physics course. Sound waves cancel out when crest meets trough, and trough meets crest (when the sound waves are same frequency and amplitude and wavelength). Noise + Noise does not necessarily = Noise. Noice cancelling headphones work on a similar principle. Send out sound waves that are a half wavelength off.

I'd think if it was as easy as is proposed, it would have been done already. So you're saying if I take two sonic booms from passing F-117A Stealth Bombers and position them such that they cancel each other out, I won't get blown eardrums? 😛 - M4H

The only problem is, the F117 cannot break the sound barrier (Max Speed Mach 0.9 <a class=ftalternatingbarlinklarge href="http://www.greenwood.wa.edu.au/factory/personal/andrew/stealth.html" target=blank>proof</A>). So, there is no sonic boom 😛. But, in theory, two sonic booms created by F-22's 😛 created so that crest meets with trough and trough meets with crest could conceivably be silent.

Hah! Nice catch!
So there, you can have just ONE F117A and not worry about a sonic boom - no need for a second one. Talk about excellent noise cancellation!

 

[DGath]

I think it works on headphones because the sound is coming from one direction, straight into the ear. But with a phsical object like a computer that produces noise, it's going in every direction. You could put speakers in front of you and have them set right to cancel out any noise coming from the direction of your computer and I guess it would work, but wouldn't it just be easier to wear the headphones?

I could be totally wrong but that's just what my common sense is telling me.

*Disclaimer* Years ago I got a D in physics senior year in high school. 😛

 

[Goi]

I tend to agree with DGath, wouldn't the distance from the speaker as well as the various noise sources(you DO have more than 1 fan in your case don't you?) to the individual cause massive phase logistics to take care of in order for noise cancellation to work?