Noise-canceling headphones, like the NoiseBuster in Figure A, are designed to remove the background noise of the environment, allowing you to hear more of the finer details in the music you're listening too, and to be able listen at a lower volume, thus reducing any potential hearing damage.

FIGURE A

The NoiseBuster noise-canceling headphones. Click picture for a larger image.

How it all works
Pro Tech Communications, maker of the NoiseBuster, uses what I like to call "Star Trek" technology to cancel out background noise. Figure B has a diagram showing how it works.

FIGURE B

Star Trek technology cancels the noise. Click picture for a larger image.

It goes like this; the NoiseBuster uses a microphone inside and outside the listening cup (numbers one and two in the diagram). The onboard electronics (number three in the diagram) analyze the signals from both and create a sound wave that is the inverse, or exact opposite, of the difference between the two, this is the "noise-canceling" wave. The noise-canceling wave is then projected through another speaker in the ear cup (number four), resulting elimination, or dramatic reduction of offending noise (number five).

So where does Star Trek enter into all this? Well, this is the exact same technology used on the TV show to penetrate enemy shields, nullify weapons systems, and protect the crew and vessels from dangerous space anomalies. Now do you see why I refer to it as Star Trek technology? Mr. Data himself could have invented it.

How well does it work?
I must confess to having a bit of a misunderstanding of how this technology and these headphones were supposed to work. I expected that when turned on, the headphones would cancel out ALL noise, but instead it merely removes the annoying "white noise" in the background that we all get used to and naturally tune out. You have no idea how loud and intrusive this white noise is until it's no longer there. Everything is so much more clear and sharp.

The NoiseBuster actually works so well that I was able to pick out details in songs and movies that I have previously missed due to background noise. The great thing is, you don't have to be listening to anything on the headphones in order to take advantage of the noise-canceling feature. Because the electronics that create the noise-canceling operate from their own power source, you can use the NoiseBusters as noise-reducing hearing protection.