When are they going to make Noise Cancelling Speakers for the Masses?

I have a set of Bose noise canceling headphones that my dad gave to me. With them on I really can't hear much of anything outside, and when people talk to me i can barely make out their voice.

Now why can't they produce a speaker that you could put inside your computer and just leave it running to cancel out the noise? Possibly all that would be needed would be a tweeter + mic to cancel out the high pitched noises that get annoying, as the lower hz is easily managable.

This post needs to be moved this is the wrong section. To answer the question they do make white noise generators already.

lol, I can't even afford the headphones.

well the "noise" canceling doesnt quiet work like that i dont think -it is a mix of insulation on the headphone it'self as well as the speaker, and since the sounds comes OUT of the speaker, it can be controlled.

ideally what these headphones do is cancel noise from coming INTO your ear from the outside - they dont stop noice going out - which would be the case for your computer.

maybe some sort of noise sbsorbing sponge that absorbs noise in the PC cause before it can reach your ear?

Noise cancelling is not any kind of insulation, its actively using a speaker to produce a "counter-sound" (dunno the terminology) that cancels out the original sound. When you put the two sounds together, you cannot hear either of them. I think Honda uses this in the latest Accords...

sounds in PC's vary greatly, and to cancel out the sound, you need the exact same frequency and loudness, i dont know.. but how "easy" would it be to make something like that?

edit: not to mention that the speaker would also have to be a whole wavelength away from the source, because otherwise it would cancel it out good enough..
edit2: it could even just add to the noise..

deathBOB said:

Noise cancelling is not any kind of insulation, its actively using a speaker to produce a "counter-sound" (dunno the terminology) that cancels out the original sound. When you put the two sounds together, you cannot hear either of them. I think Honda uses this in the latest Accords...

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sound can be described as a waveform, the cancelling waveform would be the identical sound repeated 180* out of phase

im sure we'll see the technology in the future

Mr.Guvernment said:

ideally what these headphones do is cancel noise from coming INTO your ear from the outside - they dont stop noice going out - which would be the case for your computer.

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this makes the most sense

Npetune3000 said:

maybe some sort of noise sbsorbing sponge that absorbs noise in the PC cause before it can reach your ear?

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they make padding stuff you put on the inside of your case... problem is, its pretty much like insulation... and insulation keeps heat in.... not good

I think it will come... But nobody cares! The OEMs can make a quiet computer with current low-tech methods, why invest and research in expensive electronic cancellation techniques? I think dual cores may bring this about...

Active Noise cancellation (or control) is actually a relatively simple concept. I find that the easiest way to explain ANC is this. Visualize sound as a wave form that is going above and below a line. Now imagine another wave that is exactly the same as the other one, except inverted (180 degrees out of phase). Those two waves would cancel each other out. This would leave you with empty air, so to speak. (http://en.wikipedia.org/wiki/Active_noise_control might be helpful to some.)

Now that the basic concept of how ANC works is explained, actual implementation is an entirely different matter. Most highly effective ANC systems (like Bose headphones) have a processor with predefined variables embedded into it in order to compensate for travel time of the data that it must receive, process, output to the headphones, register and process that data again and put it back to the headphones. The reprocessing is my understanding of how the Bose system works, but the rest of the process is solid. For the tech savvy, Analog Dialog did an article on creating a system similar to Bose’s design but it requires a lot of knowledge on the user’s end. (http://www.analog.com/library/analogDialogue/archives/34-02/noise/index.html)

The not so effective systems do simple noise inversion on the waves. The advantages to this are that it is extremely simple to create; unfortunately they are weak in their performance compared to processed system like Bose’s. So much in fact that some people report better sound canceling when they just have the system output sound that the microphone input picked up because the delay is so long that if you invert the output you broad cast a signal that is not 180 degrees out of phase. A sample of this style of ANC is available from headwize (http://headwize.com/projects/showfile.php?file=noise_prj.htm)

For those who are still with me at this point, I have been searching for sound equipment that would ANC an entire room and have yet to find anything. I have formed a conclusion that it is either downright impossible or so very hard that nobody has done it.


Whoo!, that is kind of a long post.

Twigss said:

they make padding stuff you put on the inside of your case... problem is, its pretty much like insulation... and insulation keeps heat in.... not good

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Not so, the insulation that is provided insulates a trivial amount of area. It is supposed to be applied to the case side and other places. When done correctly it has no measurable affect on case or CPU temps. But plunty on the amount of noise.

Actually, I did read an article quite a while back, over a year ago, where research was being done to use active noise cancellation in PCs. It was overly complicated and expensive, though it did work. They had to have multiple microphones and decent quality speakers inside the case with a separate processor to cancel the noise generated by the PC's components. Of course, it wasn't dead silent because you could still hear exhaust case fans, since it can't cancel noise once it's outside the case.

thanks for the clarification as to how NC works. - i had alwasy thought it was more an insulation matter.

Alacritan said:

Actually, I did read an article quite a while back, over a year ago, where research was being done to use active noise cancellation in PCs. It was overly complicated and expensive, though it did work. They had to have multiple microphones and decent quality speakers inside the case with a separate processor to cancel the noise generated by the PC's components. Of course, it wasn't dead silent because you could still hear exhaust case fans, since it can't cancel noise once it's outside the case.

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Two things, do you still have the link to that article?

And, One of my back burner projects is a system can cancel all of its own noise because it only has two fans venting from the top of the case(water cooled with the heater core and fans on top of the case). Put a duct of some sort on top of those fans and you can cancel out their noise.

Mr.Guvernment said:

thanks for the clarification as to how NC works. - i had alwasy thought it was more an insulation matter.

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Welcome! Also, you are right that it is a type of insulation for passively reducing amounts of noise getting through headphones or noise radiating though a room. They just don’t use that a lot on systems like Bose’s QuiteComfort, and QuiteComfort 2.

complicated technical solution that requires powered circuitry and realtime sound sampling < slower fans and larger heatsink surface areas

Sure it might be handy. But there's more than one way to muffle a cat. Use ducts, slower fans, larger heatsink surface areas, etc. I don't see it ever becoming simple enough to work effectively in something as small as a PC.

ANC can reduce the noise to an inaudible range; larger slower fans are still audible.