I'm finding this topic very interesting...

My office is in a server room and my desk right next to the racks. It wasn't too bad when I started 8 months ago, but since then the number of servers has doubled and with it the noise level. Currently there's no budget for noise mitigation materials, so I've been thinking of other ways to counter the noise.

Earlier this week I brought in a pair of ATH-M40 to listen to music with and found that they had the side effect of blocking a bit of the noise. Today I had the realization that it shouldn't be too hard to have a piece of software running on my Macbook to sample the ambient noise with the built in microphone, then pipe out the inverse-wave to the headphones, giving me a degree of noise canceling with gear that I'm already using.

I can't be the first person to have thought of this solution, but I haven't been able to find any examples of this being implemented. Anyone else know of a solution like this?