Active noise suppression

Active noise suppression technology is used in headphones. Does any one out their know how to do this for a computer fan?

you mean something that scans the sound vibrations and the frequencies and then emits a counteracting sound pulse to equalize the sound?

it works like adding 2 overlapping sine graphs offset by 180*

is this what you mean?

Headphones do it by detecting incoming noise and putting out the same noise 180 degrees out of phase out of a very low power speaker, thus cancelling the noise. This works only because the headphones are close to the ear.

To do it at the source of the noise you would need a good microphone, a DSP to do the processing, and a speaker. Or maybe you could take headphones with this feature, rip them apart and hook up a more powerful speaker, but I'm pretty sure it wouldn't work very well, if at all.

With all the reverberations occuring in and around the case, I don't think there's anywhere such a system could be placed and work properly except near your ears.

Well, the technology exists and works for sounds in car interiors. It has 4 or five mics around the interior and compensates for unwanted noise. The working model actually uses the standard spearkers for the car stereo. It's however pretty advanced and only works for a few "spots" in the car. Canceling audio is one thing, cancelling vibrations is a totally another ballgame.
Audio is differencies in airpressure, vibrations is parts moving (in any direction). For home use, you'd need to mount speakers and mics in YOUR ROOM to cancel the PC.... I think it's easier to dampen it(the PC) or put the PC somewhere else.

it is relatively simple to cancle out audio from a speaker outputting music since it is digitally reproduced and is very basic in nature. true vibratioinal audio is alot more complex and is not reproduced well on speakers (enter the whole dvd audio thing that is trying to fix that)

if you wanted a true noise supression system in the room you would need about $5000 of speakers all within different ranges ie 20 - 120 hz then a midrange at 110 to 1500 hz, etc, etc, etc

the regular 3 range speakers will not work since there is way too much info to convey with that setup. you need more like 5-7 bridges.

Okey big_bertha, you are up for some explaining now. Either I don't understand you, or, you're not explaining it clearly enough leaving room for misinterpretation.
Me: A dude who's genuinely intrested in Home Theater. I got a $10000 audio(surround capable, any format such as DTS, AC3, THX prologic etc.) system at home. I don't consider myself an audiophile, but pretty close. I totally rearranged my livingroom symmetrical into a home theater, nailing dampeners to the wall, built extra stiff reinforced door, hanging up thick thick carpets to absorb and dampen rebounds. There were just speakers, tvstand, and heavy audio equipment.

Who are you? You choose to write in a very technical way, but making very little sense to me.

big_bertha said:

it is relatively simple to cancle out audio from a speaker outputting music since it is digitally reproduced and is very basic in nature.

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I'd say that the music is reproduced by an analog device in the end, the speaker. The audio may be stored in digtal form. But a lot of sources are still analog, radio, tv, vcr.

big_bertha [/i][B]true vibratioinal audio is alot more complex and is not reproduced well on speakers (enter the whole dvd audio thing that is trying to fix that)[/B][/QUOTE] I belive that speakers would qualify as an "true vibratioinal audio" device. It shuffles back and forth said:

if you wanted a true noise supression system in the room you would need about $5000 of speakers all within different ranges ie 20 - 120 hz then a midrange at 110 to 1500 hz, etc, etc, etc

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Or a slightly bigger box filled with dampening material around the PC. It will feel pretty "truely supressed" if you do it right, and it won't kill your wallet.

big_bertha said:

the regular 3 range speakers will not work since there is way too much info to convey with that setup. you need more like 5-7 bridges.

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If there isn't too much square wave into the audio spectrum I don't think you need anything really special speakerwize. I still havent heard any computer sounding more annoying than listening to square wave tones. THAT is a murder on the mind.. (at least my mind)
Well... I can't claim that my speaker system can cancel audio and vibrational "disturbances" since I haven't tried it. Nor am I intrested in trying it either. I the guy who creates vibrations and audio disturbances! *waking up the neighbors! T2 playing!!*

I was thinking of only trying to cancel the noise from the CPU fan not every sound the computer creates. I was thinking the fan spins at a constant speed and puts out a fairly constant sound. How can I sample that sound and reproduce it out of phase 180 to quiet it down. Not like 100 percent perfect, like 60 or 70 percent. Is it possible and not cost to much. Like $100 or less.

Here's my active noise suppression: Turn up the volume!!!

same thing here... turn up that music.
soon you will forget that your computer makes noise

or remove the damn fans and get watercooling...

Mr.DLucey said:

I was thinking of only trying to cancel the noise from the CPU fan not every sound the computer creates. I was thinking the fan spins at a constant speed and puts out a fairly constant sound. How can I sample that sound and reproduce it out of phase 180 to quiet it down. Not like 100 percent perfect, like 60 or 70 percent. Is it possible and not cost to much. Like $100 or less.

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As big_bertha pointed out, there is the actual sound from the fan spinning + air hissing. Then there is also a sound that is created by fan vibrations interacting with the motherboard and case.
Air hissing is easiest to dampen with soft absorbing material(like sponge-a-like materials. I'll be back with more, gotta go!