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Noise cancellation for PC's?

J

jaydee

Diamond Member
We all want quiet PC's spending quite a bit of money sometimes to achieve it, and usually going with fans that aren't as high performing to eliminate as much noise as possible. But what if... instead trying to eliminate the noise, why not just 'cover it up' with a noise cancellation unit? Have a microphone near your case, a hardware noise canceller device, and 'line-in' it into your speakers (headphones would obviously be ideal).

Is it feasible? I know it would cost a bit (I don't know, $50?), but it should last quite a while and you could put any sort of fan in you want.
 


Bump

I asked this a few months ago and go no input. Hopefully you will do better.

It's seems with all the spare GHz we have laying around the computer should be able to

A: analyze the fan noise/case vibration noise
B: Generate a wave that cancels that noise

Imagine a lil software plugin that silences your PC...............

 
That's not a bad idea either... You could even run it right through your sound card, making it completely discrete!
 
they have stuff like this for industrial combustion engines. It would be hard to do in a case since the noise is coming from different places and not just one direction. How stuff works explains it a little bit if you are into a short read. Here is the linky for your enjoyment.

Muffler

Active Noise-Canceling Mufflers
 
It would be hard to do in a case since the noise is coming from different places and not just one direction.
Click to expand...
But what if it's outside your case (near you). You could program in the frequency from a reading when they (the fans in your case) are the only thing making noise, then you could digitally adjust the phase shift each time you boot up, ensuring perfect deconstructive interference.

Would that work?
 
FYI, there is a company that makes something which does just what you're asking (for noise in general, not necessarily computer generated). I had investigated this because my brother lives next to a restaurant that has a weekend band. The device I found was for home use, but I wanted to try to mod it to work outside and on a larger scale. Do a search on Yahoo, which is where I found it (sorry, no longer have the link).
 
lookin4dlz

I've seen such a device too and it was like a grand for home use.

What I want is say a $50 software program I can just run on my existing hardware.

Gotta do something with all that extra horse power...........
 
There's no reason it can't be done in software. There are plenty of freeware frequency analyzers (simple FFT's) out there already. All you'd need is some sort of user interface to manually adjust the phase, and output it back through your speakers (amplitude should be taken care of already).

Programmers out there: how hard would it be to write code for this user interface?
 


I think SETI is a good thing

But it runs in the background when you are not using your computer right? Need the use the HP I am waisting as I type this my CPU is online at 5 to 25% utilization.........

OTOH they almost fired a guy at work the other day for running it, so be aware of your companies policies before you try to help out at work......
 
Originally posted by: trikster2
I think SETI is a good thing

But it runs in the background when you are not using your computer right? Need the use the HP I am waisting as I type this my CPU is online at 5 to 25% utilization.........

OTOH they almost fired a guy at work the other day for running it, so be aware of your companies policies before you try to help out at work......
Click to expand...
That's an understatement to say the least. Remember Dave McCowen?
 

Yeah but Dave was ambitious running it on a ton of computers he was responsible for.

This poor guy was just running it on his own workstation, no place else, and upper management wanted to sack him. So be careful out there!
 
Noise cancellation is tricky. The problem is that noise waves propagate from the noise sources, bounce off of things and eventually make it to your ears. It is relatively easy to cancel noise using headphones - you are cancelling at the receiver (your ears). But when you add external speakers into the equation, it becomes more tricky. Say you put a speaker in your case and have it emit "anti-noise" (180 phase-shifted sound waves). This will result with a noise "dead spot" at a point in your case that you don't care about, but it won't change anything where you actually are - in fact if the waves coincidently peak where you are sitting you can double the noise you actually hear (constructive interference). Plus merely moving your head slightly could change the effectiveness of the scheme. Bottom line: this won't work very well - if it works at all. Noise cancellation at the walls of the case is an interesting possibility to reduce vibration, but adding vibration absorbing material makes more economic sense.

Ideally, you could add microphones to points near your ears and come up with a complex algorithm to have external speakers induce destructive interference at these points. But this would be very complex and I'm not sure whether anyone outside of labs has technology like this. It would take a fair amount of CPU power to process the signals.
 
Ideally, you could add microphones to points near your ears and come up with a complex algorithm to have external speakers induce destructive interference at these points. But this would be very complex and I'm not sure whether anyone outside of labs has technology like this. It would take a fair amount of CPU power to process the signals.
Click to expand...



Found it. I guess it's not available for home use yet.........

His patented Silence Machine comprises microphones for sound sampling, a powerful computer for generating anti-noise, and loudspeakers for blasting that anti-sound at the incoming noise.

The size of the shadow areas where the sound and anti-sound waves cancel each other can be varied by changing the number of loudspeakers or their positions. Any microphones or loudspeakers will work, says Wright, but the more directional they are in terms of sensitivity the better the result.

Signal processors in the computer measure the frequency of every component in the noise signal, and use this information to create the anti-noise-sound with an identical frequency but the opposite phase. This means that a peak in the noise wave meets a trough in the anti-noise, cancelling out the sound.
...

A Silence Machine suitable for use in factories is ready for commercialisation, says Wright ...

He expects an industrial-scale Silence Machine to cost around £10,000, while smaller domestic versions will sell at about £1000. It could be used to create quiet zones in a garden, for example, or around your house, blocking out railway, aircraft and motorway noises, without affecting pleasant sound such as birdsong.
 
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