What is active noise cancellation?


The first time I tried headphones with active noise cancellation, I fell in love. I don’t just take them on planes, I use them in the office. I keep them with me whenever, because you never know when a loud truck is going to park outside or whatever. Those things are pure magic, worth what I paid for them.

Active noise cancellation works off a principle that doesn’t seem like it would make sense. If you take a sound, and play back another sound that is its mathematical opposite (more on that in a second) then both sounds go away. All I can tell you is, it works.

Sounds are really complex pressure waves; half the time they’re “up” meaning positive pressure, half the time they’re “down” meaning negative pressure. All you need to do to make them go away is more or less instantly create a wave that is up when the original wave is down. Of course, “all you need to do” makes it seem easy, when it actually takes complex, fast microprocessors to make this happen. If you create the “anti-sound” a fraction of a second too late it will actually amplify the original sound and that’s not helping anyone.

What’s even cooler is that you can manipulate the wave so it blocks out some sounds and lets others in. You can stop the sound of cement mixers outside your door but let the sound of your coworkers or your computer in easily.

I use active noise cancellation a lot in my job, even though it’s not by nature a noisy environment, but the folks who really benefit are people in loud vehicles. At Solid Signal, we sell a ton of these BlueParrot headsets because truck drivers love them. They are specifically tuned to eliminate the kind of noises trucks make while letting in things like sirens blaring behind you. They’re also wireless, using Bluetooth technology for connection, and they’re the ultimate in comfort for long hauls.

Trust me, if you work in any sort of environment with low-frequency noise you’re going to want something with active noise cancellation. Most devices are tuned so that you’ll still be able to hear the important stuff around you without having to hear the loud noises that distract from your day. This makes them a lot better than plain hearing protectors which essentially cut you off from the world.

Active noise cancellation… seems like it shouldn’t work but I’m oh, oh, oh so glad it does.

About the Author

Stuart Sweet
Stuart Sweet is the editor-in-chief of The Solid Signal Blog and a "master plumber" at Signal Group, LLC. He is the author of over 5,000 articles and longform tutorials including many posted here. Reach him by clicking on "Contact the Editor" at the bottom of this page.