#89: Laptop antinoise

As the owner of a laptop which had begun to sound like a jetplane at takeoff, the issue of quietening such machinery has been at the forefront of my mind (or at least my auditory cortex).

The various sources of online Ubuntu help were scoured (thanks, K) for insights into how reduce the fanspeeds without frying the chips. This was pretty successful but it left me wondering what I had to do to get absolute silence.

speaker181.jpg

Today’s invention is to supply each laptop (or desktop box, come to that) with an antinoise generator. Given that the fans tend to have a very small number of operational speeds, it should be possible to tune an antinoise system to cancel each of these quite effectively…so that even if you happen to find yourself solving 3-D acoustic wave equations, the machine can stay silent and still not melt.

No need for aftermarket hardware of course -simply record some fan noise samples, invert the amplitude (you might get away with a simple phase shift of 180 degrees, if you have a pitch-perfect machine) and play it back through the speakers.

Probably a good idea to run a synchronisation program once at startup, and only periodically thereafter, to account for drift and changes of fan speed (running a big dsp program continuously in the background might rather defeat the purpose of the exercise).

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