That is the theory, the real world does not always follow suit. There are good noise cancellation headphones and bad ones. The bad ones sound terrible and only mute the outside noise a little and eat up batteries. To be successful at canceling noise, everything must be in order. The lower the quality on any one component, the less effective the noise reduction will be. So how do they work? Basically the headset has a small circuit inside it that samples the outside noise. It then creates the exact opposite noise and plays it through the headphones along with the music. The noise from the outside plus the sound injected from the noise canceling circuit will cancel each other out at your ear resulting in music without the noise. How successful this is in practice varies wildly with different headsets. Another point worth mentioning is that high price doesn’t always mean better performance. Some very high priced headphones out there are simply terrible at noise reduction. You really have to put a set on and try them out before buying. This task is best done in a store, not trying out and sending back every headset in a catalog online.

Last, but of course not least, when evaluating noise cancellation headphones, keep in mind the estimated battery life. If you aren’t getting at least 20 hours or so on a single set of batteries, then you are going to need a lot of batteries. If the best set of headphones is a battery cruncher, though, I guess it’s time to get rechargeable batteries.

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