ANC for computer noise reduction?

[JingP]

I've been interested in Adaptive Noise control for a while. I'm a math guru so I can crunch the LMS figures.



Sadly my physics fails me when I need it most. Plus I am not familiar with the design of these systems outside of leug and the olsen-may classical cases.



Anyone have any idea how well an adaptive feed forward system would work in this case with adaptive feedback error control. Would this cancel globally?



If anyone can give me a run down on this topic as it relates to computer generated noise, it would be greatly appreciated.



But my simpleton ideas is as follws:





NOISE---->control mic
^.................|
^.................|
^.................|
speakers<---DSP 180 shift
............^
Feedback mic^


ignore the .........

 

[Wango]

Active noise cancellation doesn't work well with speakers since the microphone signal is not coming from where you would perceive the noise. In fact, I would venture to say it doesn't work at all with speakers.

There are many headphone-based active noise cancellation solutions you can buy/build, though. In my experience, they also have problems, because the frequency response of the headphone drivers and the microphone is not perfectly flat. Nevertheless, they do work fairly well.