Not Sure If This Would Work

[atiVidia]

has anyone tried using one of those noise cancelling thingies and connecting them to the speaker set? if u dont understand, heres wht i mean:


speakers----<-----------
                       |
                       ^
                       |
                       -----<-------noise canceller--<------inside the comp
                                               |
                                               ^
                                               |
                  comp. speaker output(for regular sounds)

u think it might work for producing an "artificial" silence?

[DarthInsinuate]

i'm not sure about the diagram, is the 'inside the comp' thing supposed to be a mic? i'm assuming this is some sort of negative feedback system - the theory for these systems is sound ( :huh: ), apparently farmers in tractors use them :unsure:

so by all means why not try this thing out?

[tesco]

I dont understand the diagram at all lol... explain it a bit better?

from what i understand, you want to plug in the computer's sound + the sound inside the computer (fans, drive, etc) and amplify them both through the same speakers. :unsure: :lol:

[Livy]

im sure the speakers have to be setup specifically in certain places for it to work properly.
all it does is play the negative of the noise so that the two noises add, since one is the negative the sum is zero. so no noise.
but im sure it would cost alot.

[atiVidia]

Originally posted by Livy@19 March 2004 - 20:30
im sure the speakers have to be setup specifically in certain places for it to work properly.
all it does is play the negative of the noise so that the two noises add, since one is the negative the sum is zero. so no noise.
but im sure it would cost alot.
heres 1 that mite work better: just buy a speaker (crappy cheapass one) and hook it up to the noise canceller. hook a mic to the noise canceller as well, and keep the entire contraption inside the case.

shuld stay below $170, and might even work better than conventional silencing methods!!!

[lynx]

I think Livy is right on this one.

At some points the sounds add together, but since one is reversed that is like subtracting the sound so you get silence. But in other places (depending on the wavelength of the sound) the reversed sound will be effectively inverted itself so when the two sounds are added you get twice as much noise.

The only way to avoid this would be to have both sound sources located in the same place, in other words your speaker would have to be part of your fan.

Sound cancelling systems often work in cars because the sound they want to cancel comes through a specific point such as the wheel arch - the wheel arch itself is actually vibrating. They can then mount a speaker at that point so that the speaker vibrates with the metal panel, and issues sound waves which are a reverse of the motion of the speaker thus giving proper cancellation.

Edit: the alternative is to cancel the noise as it enters your ears. I think that's what Darth meant when he talked about tractors - the farmers wear head phones which are fed a reversal of the noise from the angine and equipment.

[Livy]

yeah, you also get mobile phones and handsfree kits with noise cancelling in it now,
we done something like this in physics. two speaker about 3m apart hooked up to the same source, a signal generator. and as you walked through the room, it went from loud to quiet as the waves intercepted. creating normals, highs and lows.

[tesco]

How can i try this out? what equipment should i use?

[Livy]

bump, more info
http://www.headwize.com/projects/noise_prj.htm