Silicon chips shuffling all those electrons around inside modern PCs, gaming consoles and home theater systems generate a lot of heat that needs to be dissipated to stop the machines going into meltdown and ruining your day. Fans are the most common form of cooling for modern electronic devices but they can generate a lot of noise that can leave your lounge room or study sounding like an airport runway. Sweden-based company RotoSub has developed an active noise control (ANC) system that is built into the fans themselves that promises to almost eliminate the fan's mechanical noise and leave little more than the sound of the air blowing through the fan.
Noise-cancelling technology like that found in noise-cancelling headphones cancels out ambient noise by generating an "antinoise" signal. This is a sound wave with the same amplitude as the original sound wave, but with inverted phase, so that when the two sound waves combine they effectively cancel each other out. Such systems require a microphone to pickup the original sound wave and a speaker to generate the antinoise signal. Additionally, in the case of a fan where noise is being generated on either side, two speakers would be required to combat both the downstream and upstream noise.
To overcome this problem, RotoSub has built the ANC system into the fan itself so that it requires no speakers at all. This is accomplished by slightly bending the fan's blades to alter the angle of attack so that they act as the speakers to generate the antinoise signal. And because the antinoise is aligned in both directions, the noise is reduced both upstream and downstream. The company says fans incorporating its ANC technology have the same form factor and aren't any larger than traditional fans.
RotoSub isn't selling fans using its ANC technology itself, but is instead licensing the technology to other companies. If the video demonstration below is any indication of the system's performance, here's hoping a few companies take them up on their offer.