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Question:
Does anyone know anything about how antinoise works, or could you point me in the direction of some good references? I am planning on doing a a science fair project on the subject. Part of it would be antinoise "theory" - how it works, and I would build a antinoise device for practical use and measure results. What would be involved in building such a device? I would need to convert Audio to digital sample, perform the antinoise reciprocal function electronically and transmit the new signal almost instaneously going back from digital to audio... I know this is a complicated undertaking. Does anyone have any comments/suggestions/ tips/warnings? Thanks,



Replies:
Arthur C. Clarke wrote a famous short story about this many years ago. I think it is doable but only over a relatively small volume, maybe a small room...

John Hawley


That was in "Tales from the White Hart" by the way (the short story about this). Except real "active noise suppression" does not work nearly as well as the one in the story did.

Basically you have to measure the pressure at various points in the room with a pretty rapid detector, and then feed it into a processor to be sent out to speakers - I think you can do a pretty good job with feedback loops. I recently heard something about plans to put this kind of thing on airplanes to suppress engine noise. You might check recent issues of acoustical journals or leaf through the past few years of scientific American (I think their "science and the citizen" section has had one or two articles on this recently



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