Noise Canceling Headphones

Locked in my office is a roaring beast--the return vent from the climate control system. The white noise might be comforting, but the low-frequency rumble is annoying. Each morning I turn on the radio, but risk bothering my co-workers if I turn it up enough to drown out the background noise. This week I tried out a pair of low-cost noise canceling headphones. Upon putting them on, I immediately noticed the dramatic decrease in background noise. The music sounded great, but I could turn the volume down and still hear it well. I'll look forward to trying them on an airplane. Here's how they work:

NoiseBuster uses a microphone inside and outside the earcup (1) to listen to the offending noise coming into the ear (2). Using electronics (3), the system takes the information from the microphone and uses it to create a noise wave that is identical to, but directly opposite of, the one coming into the ear. The "anti-noise" wave is output through a speaker (4), also located in the earcup. When the two waves (the offending noise wave and the anti-noise wave) meet, the noise is significantly reduced (5).