Cancelling Out CPU Fan Noise

Percy_Blakeney writes "After realizing how noisy his computer was, a professor at BYU has created a new CPU fan that uses small microphones and speakers to cancel out its own noise. It isn't perfected yet -- it only nixes the whine, not the whoosh -- but it looks like it could be promising, especially given the professor's background: making jet engines quieter."

now for the hard drives

[xobes]

The noisest part of all my computers i the hard drive, not the CPU fan.

Why go through all this trouble?

[Zakabog]

Why? Can't you just get a really quiet fan? My CPU fan is noisy but I don't care, if I wanted to I could build some sort of box to enclose the noise so I don't hear it. Or I could use water cooling which is much quieter. Or I could put my computer further away from where I am (like in a closet or something, like the box idea.) This just seems like a complicated solution to fix such an easy problem.

Noise and Heat

[pholower]

It would seem that putting more electronics in the device would only create more heat. Then you would have to increase the fan speed, and then increase the amount of sound cancelation in turn, increasing the fan speed again. An endless cycle. Why not just go with a case that acts as the heatsink?

Re:now for the hard drives

[wed128]

i'm sure in theory the technology could be adapted...

Me too!

[slifox]

I thought of this too, a while back.

The problem is that the fan noise isn't a constant noise and theres no way to create an inverse wave exactly when the sound happens--there will be a delay.

Good to see this concept working though.

Re:Noise and Heat

[thebes]

The amount of heat that a small microphone and speaker generate would be small enough that it would likely be transmitted through whatever the mounting system was made of, into the heatsink itself, and thereby take care of itselt. The heat increase would be negligible.

Re:Why go through all this trouble?

[Anonymous Coward]

Because we're at slashdot. We don't need working and simple solution - we need cool gadgets, strange hacks and non-working geekythings.

Re:Noise and Heat

[Anonymous Coward]

Amazing how this simplistic thinking gets modded +5 Insightful. At least explain why you group together a 1 Watt speaker with a 60W CPU. God forbid you actually think the microphone 'electronics' produces more heat since it - well it's more electronics after all.

Your solutions are crap

[Chuck Chunder]

Quiet fans tend to get noiser with age.

A box is not going to be good for heat dissipation or size constraints.

Water cooling is certainly not going to be cheaper or less complex.

If an active sound nullifier that will automatically adapt to the changing noisyness of a fan as it ages can be made for as little as $20 it is surely a more credible solution than your suggestions...

Wrong direction

[Anonymous Coward]

All this does is allow PC makers to get away with making hotter and noisier systems. We should be pressuring the industry to be cooler and more efficient.

24 volt fans

[cyber_rigger]

If you don't need a massive airflow try a 24 volt fan. They still provide air circulation and are very quiet running on 12 volts.

Power Supply

[jmichaelg]

I installed an 80 mm Panaflow on top of a $30 all-copper heatsink to cut the noise from my computer but it didn't do much. As soon as the cpu fan noise was gone, the power supply noise was that much more noticeable. I ended up installing a new power supply. It was the best $80 I ever spent. The combination of a quiet cpu fan and quiet power supply result in a reasonably quiet computer. Not dead silent but at least it's no longer objectionable.

Or, instead

[lingqi]

Design quieter cooling technologies.

I mean it's not like it's not possible.

Case in point #1: NEC (in japan) has a water cooled computer now on sale to the teeming millions. water runs over the CPU and goes into a radiator to the back of the case. the radiator sits just outside of the power supply fan, which turns at an incredibly low speed (kinda like the apple G5 fans). Damn quiet.

Case in point #2: Mitsubishi, after not building any planes since WWII (zero fighter was by them, after all), entered the business-jet arena. The first thing they did was to design a new shape of turbine intake blades using computer simulation that cuts something like 10dB off the engine noise compared to traditioal strait blade intakes.

So, instead of brute forcing one's way around the noise problem, there are more elegant ways!

Re:I should have patented it...

[Anonymous Coward]

A noise canceller that makes the original noise worse? Errr....that's just a broken noise canceller, not a potentially damaging side effect. Even the most rudimentary testing of it would reveal any accidental reinforcement, and it probably wouldn't wind up being a very popular product.

Not a good use of energy

[vandan]

Cancelling sound with sound sounds cool, but it's a waste of energy. Surely there are cheaper, more environmentally friendly ways of protecting our sensitive ears from the nasty CPU fan noise.

Every little bit counts. Just imagine if we didn't have to invade Iraq for their oil because we could properly manage our energy usage and R&D into renewable energy sources.

Nope

[Sycraft-fu]

Sound is a wave, specifically a compression wave. It is fluctations of air pressure, which your ear interprets. You can see this in how speakers work. They vibrate back and forth to produce compression and expansion waves. Well, as with all wave dynamics, if you hit a wave with it's opposite, it cancels. Quite simple to think of why with sound. You have a high pressure peak and an equal low pressure peak that collide. The net effect is zero pressure (in relation to ambient atmospheric pressure).

Now if you screw it up and don't time it right, yes, you could increase the sound. However provided your system is indeed doing it's job and producing opposite waves in correct time alignment, it cancels out.

Try it yourself some time. Take two identicle speakers and feed them both the same sound (as in one mono sound to both channels, not a single stereo source). Reverse the polairty on one speaker (plug the black plug into the red and vice versa). If you have them setup normally and listen to the sound far away, it'll simply sound defocused, as though it has no apparent centre or source. This is a good way to focus your speakers, the more defocused an out of phase sound is, the more in focus an in phase sound is. However now take them, get them right next to each other, and point them at eachother. You'll hear almost nothing. PRetty much all you hear is the sound that radiates from the cabinets.

I use this trick when I'm burning in speakers. New speakers come from the factory with everything a little tight, as everything does new. Over the first month of playing they slightly change their sound as they get to their normal "burned in" point. It reach it quicker, you can just pump some white noise through your speakers. Well loud white noise is likely to piss off the neighbours, so I invert one speaker and have them face each other. Reduces it to a pretty minimal level and gives the speakers the desired workout.

woosh would be hard to cancel

[nomel]

cause it varies depending on listenning angle, where the whine is pretty constant.

probably why he's having trouble.

Re:Your solutions are crap

[Zakabog]

The fan will change noises as it gets older and somehow the microphone and speaker will remain perfect forever? If either the microphone or the speakers are damaged they'll end up creating more noise then they cancel out. What happens if the microphone starts picking up feed back then your computer's creating more noise than it started off with?

Re:Wow

[Genda]

Actually it has been used in a variety of applications for some time. Back in the 70s a huge diesel generator had mikes place on it, then further out was surrounded by large speakers. The mikes picked up the motors full spectrum and the speakers played it back at the motor. There were two marked effect;
1. The generation room went from deafening to almost whisper quiet...
2. The motor efficiency jump markedly. It seems that one of the significant causes of mechanical inefficiency, is the increased friction due to vibration (both resonant and nonresonant) in the motor. By canceling out that vibration, the motor operated more smoothly, wore out more slowly, ran cooler, and used less fuel.

Of course, at the time, this only made economic sense with huge motors who's cost of maintenance, operation, and replacement justified spending megabucks in improving performance and endurance.

With the new technologies available to produce sound, or damp it in a given space... this technology could be used to improve efficiency and eliminate noise pollution from automotive engines, turbines, and a whole host of noisy machines including the fans in our computers.

I mean, if Bose can do it with your headphones, why shouldn't we do it with our environment...

Genda

- Why are there so few Zen performers? Because it's no fun making a curtain call to the sound of so many people clapping with one hand.

Re:Nope

[Anonymous Coward]

Even more amusing than the supposed audiophiles who believe their speakers should be burned in are those who believe that solid-state electronics and even cables should be burned in. They buy (or download via BitTorrent nowadays) CDs from scam artists that supposedly contain "precisely computed noise" that stresses their equipment just so. It's really quite hilarious, if pathetic.

I have disgustingly acute hearing, perfect pitch, and have listened to a hell of a lot of music of all kinds, and I still find all of these sorts of audiophile claims to be hokum. It's an entire industry founded on lies and bullshit elitism. So frankly, let them waste their money - they deserve it.

Re:Not a good use of energy

[Vellmont]

Whaa? Less than a watt of energy used to power speakers is a "waste of energy"? Your post is a waste of energy. Every little bit does NOT count. I'm really sick and tired of this nonsense of adding up miniscule "savings" and making them into big sounding numbers to the ignorant masses.

There's this attitude that's developed among the eco-freaks in this country that they can save the world by reducing their own personal consumption by .01%, because "every little bit counts. Not flushing your toilet to "save water" is idiotic. If you want to "save water" don't water your lawn, or stop lettings farmers irrigate farm land. Worrying about a watt of energy to do noise cancellation is equally idiotic. If you want to use less oil stop driving the goddamn gas guzzling SUVs.

Re:Not a good use of energy

[AVGVSTVS]

I think you miss the point, its not about saving the world, its about totalitarianism. "It is a waste of energy" is not an objective, rational, scienfitic statement of efficiency, is a value assesment. 'Your personal comfort and way of life is unacceptable if you do not conform to my political idealogy and support my causes'. That is why they often border on the rediculous, the mindset is so entrenched that anything not deemed valueable in thier world view is automatically declared wasteful under a catch-all excuse of energy conservation and "saving the world".

I'm just going to say it

[Anonymous Coward]

This is how I think it should be. We go down to the point where processors are low power enough we don't need active cooling and we add power within those constraints. To get more power we just add more processors. So for like a powerful desktop we could have 4 or 8 fanless processors...

And we'll all be yeomen farmers in 2012.

But seriously, isn't it obvious chip manufacturers have relied increasingly on "overclocking" their chips in order to show meaningful performance gains? It's a clear indication that the current trend in microprocessor performance has levelled off. More and more exotic cooling solutions are required for even the most humble new PC. What ever happened to the 486 days when we didn't need heatsinks for the top of the line machine?

Results will vary with frequency

[sammyo]

This is not a new idea and with a fairly constant tone may be possible but a complete solution for any frequency, direction, range and environmental configuration will be incredibly hard. Different frequencies will bounce and be absorbed by different materials, ah differently. ;-) So unless the damping tone is generated from the precise location as each 'annoying sound, a different calibration may be needed.