Discussion in 'Article Discussion' started by Gareth Halfacree, 13 Jun 2013.
Borrows RotoSub tech for silent fan.
WIth an larger electromagnet creating that cancelling effect, will we get the same high frequency whine that you get with an awful lot of devices?
I know i'm not alone, but there are only a few people who can hear it and it annoys the piss out of me. Would rather have a dull hum than me thinking i've got tinitus...
You're thinking of transformer coils "sticking" and "releasing" at AC frequency, aren't you? This system should be "DC" (or at least decoupled from mains ripple by the PSU) and tuned to the "offending" noise only in theory...
Of course if mains ripple does make it through the PSU then this system couple amplify it slightly...
Seems like only the tonal sound was cancelled. Was that the point?
To be honest, I don't mind hearing a low frequency hum, it covers over the slight noise my PSU makes due to the terrible power supply in my area.
Can I get this for my pump please.
More to the point can i get this for the kids
What a fail on so many levels ...
1: As noted in the article, CPU fan is hardly the loudest source of noise in a computer. There are other active sources (GPU and PSU fans, HDDs etc.) that this will no affect, but the one I find by far most irritating is ...
2: Resonance. No matter how many spacers/pads I use and no matter where I put them, some bits (of enclosure ?) will eventually slowly drift in and out of resonance. I can only imagine how an additional noise source that is frequency locked with existing noise source is going to impact that.
3: While active noise cancellation sounds (no pun intended) good in theory, there's always the issue of phase shift (microphone takes finite amount of time to record the noise, speaker takes finite amount of time to reproduce its inverted waveform). Combined with issue #2 this is just begging for more problems (induced oscillations), something that can happen with any system employing feedback loop.
4: And ultimately, a very practical consideration of active noise cancellation: how do they expect to project the inverted noise in exactly same direction(s) as the original (CPU fan) noise ? This is easy in headphones (outside noise comes through the ear canal), not so when dealing with an object that radiates noise in virtually every direction, while there is no such thing as an isotropic loudspeaker (plasma speakers aside, they are not going to employ this kind of technology here, besides it couldn't overlap the original noise source). Inverted noise signal will not cancel out with the original noise the further you move away from the axis of projection of that additional noise, meaning that you'd have to sit in one spot to benefit from this, while you'd get amplified noise (up to twice the sound pressure that CPU fan generates alone) everywhere else.
It's only a tech demo at the moment, but I can see it leading on to things.
Noise cancelling sound is used on top end cars if it can be adaptive enough to cope with a cars cabin why not on the inside of a case?
It may only be a basic tech demo at the moment but I think it shows something that could be very good in the future.
I agree. While it may not currently be perfect and I wouldn't buy the first model released, it's nice to see companies investing in this sort of technology. In a few years a powerful, totally quiet PC may be a possibility.
It's been ages since I browsed Bit-Tech ...
I think the really interesting application here will be if this ever migrates to laptops. My desktop, I don't mind so much. Three active fans, and we can get quiet-enough fans these days that the noise levels are fairly inaudible in a "normal" environment, particularly if you think about silent cases, water cooling, etc.
Laptops, however, are another story. The tendency for heat build up is high, and the noise levels of those tiny fans can be excessive as they try to cope with limited air flow and very tight spaces. And since laptops tend to be much closer to the user's ear, that noise becomes much more oppressive. If this tech makes it into laptops, you'll start seeing much better cooling solutions, as they can start pushing more air with less audible impact to the user, making the laptop experience that much better.
That is a very good point - I could see that working really well.
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