Why You Can Trust CNET Noise-canceling vs. noise-isolating headphones: What's the difference?
These two types of headphones both filter out noise, but they do it in very different ways.
Is there a difference between noise-canceling headphones and noise-isolating headphones? Yes, and despite their similar-sounding names they work in fundamentally different ways. One isn't necessarily better than the other, it's more that each is intended for different uses. Most noise-canceling headphones have noise isolating properties, but can work without the latter. Noise-isolating headphones only "cancel" noise in that you hear less of it.
Confused? You're not the only one. Some headphones claim to be be "noise canceling" when they're really noise isolating. And it's not a trivial difference. Depending on your budget, how you intend to use them and a few other factors, you might be more interesting in noise canceling over noise isolating, or vice versa. Here's the difference.
Read more: Best noise-canceling headphones for 2021
Noise canceling (aka "active noise canceling" or ANC)
- Needs power (has batteries)
- Not as reliant on fit as noise isolating
- Good for low-frequency droning sounds
- Not good for quick or high-frequency sounds
Generally speaking, noise canceling is what most people are actually looking for when they think of either of these terms. Those famous Bose and Sony headphones you see reviewed and advertised? Those are noise-canceling. Today noise-canceling headphones are available in over-ear and in-ear (a.k.a. earbud) models.
Read more: Best noise-canceling true wireless earbuds for 2021
The fundamental difference is that noise canceling is an active, electronic process. Noise isolating is, basically, passive -- something to wedge in your ears to block out sound. They're basically earplugs, except they can pipe in your Spotify.
How noise canceling works is actually rather fascinating. Sound waves are, well, like waves. The compressions and rarefactions "move" through the air, your eardrum moves with them, and your brain processes this as sound. These compressions and rarefactions are like the peaks and troughs of waves in the ocean.
Microphones built into noise-canceling headphones listen to and analyze the sound waves of the world around you. Then, an inverse of that wave is created by the headphone. Sending a trough when there's a peak, and sending a peak when there's a trough. Sending a compression when there's a rarefaction, and sending a rarefaction when there's a compression. When the "real" sound of the outside world and this manufactured "opposite" sound hit your ear, they cancel each other out.
Instead of waves if you want to think in numbers, if the outside world is creating a +1, the headphones create a -1, so your ear gets a 0. The sweet 0 of silence. Well, mostly. But we'll get to that.
Done well, the results are impressive. The best noise canceling headphones can reduce certain noises significantly. They work best on low-frequency, droning sounds. Aircraft engines are a great example. Car tire and engine noise on the highway is another. Even noisy air conditioners can be reduced fairly well.
However, most sounds are not affected by noise canceling. Fast, transient sounds, like an alarm beeping, or higher-frequency sounds like babies crying, aren't going to be reduced by much, if at all. This is the main reason people are disappointed with noise-canceling headphones. The marketing implies they'll create a cone of silence. They don't. They reduce sound, they don't really "cancel" it.
That said, with the sounds they're good at reducing, they're great. I've flown hundreds of thousands of miles over the last 9 years and I wouldn't step foot in a plane without a good pair of ANC headphones. They make flying significantly more pleasant. You'll still hear neighbors crying and babies talking or whatever, but the tiring, endless engine drone is minimized significantly. If you take a train or bus for your commute, these will likely make that a lot less annoying too.
One other important thing to keep in mind. Just because a headphone has noise canceling, doesn't mean that noise canceling is any good. Like the performance of most tech, there's good and bad noise canceling. Cheap, mediocre noise canceling likely won't do much, if anything, to reduce any noise. Frustratingly, the amount of claimed noise reduction does nothing to tell you how well a headphone will cancel noise. Two headphones, both claiming "15 dB of noise canceling" could perform completely differently.
Lastly, know that those noise-canceling waves can create a sense of pressure, and for some folks with sensitive eardrums, that can cause a bit of discomfort.
Noise isolating
- Passive (no batteries needed for the noise isolation)
- Good fit is crucial
- Good for mid- and higher-pitched sounds
- Rarely as effective as noise canceling at lower frequencies
As you've probably figured out by reading this far, noise isolating is the far easier way of reducing noise. It's basically the equivalent of sticking your fingers in your ears, though probably a bit more comfortable.
Most in-ear headphones (aka earbuds) that go into your ear canal are, to some extent, noise isolating. How much ambient sound noise-isolating headphones reduce is a combination of their design and how well they fit in your ears. Everyone's ears are different, and getting the right fit is crucial with any headphone. Doubly so if you're trying to keep out the noise around you. Not only will a bad fit let in more ambient noise, but it will "let out" bass. Changing the tips on your earbuds could radically change the sound, and perhaps greatly improve their noise isolation abilities. Most headphones come with multiple tips. It's worth trying them all to see what you like best. There are also aftermarket tips available for many earbuds, some even with memory foam that might work better for you.
Read more: AirPods vs. AirPods Pro: Should you spend the extra $80?
A good representation of noise-isolating versus not are the Apple AirPods models. The standard AirPods -- the newest model is the AirPods 3 -- just sit in your outer ear, which is why many people find them comfortable, but not especially effective at blocking external noise. By contrast, the AirPods Pro push into your ear canal and seal you off from outside noise (assuming you get a tight fit). Of course, the AirPods Pro also offer active noise-canceling -- so they are both noise isolating and noise-canceling. (As we said: Yes, it's confusing.)
Over-ear headphones, at least the ones that aren't the "open back" variety, typically offer a fair amount of passive noise isolation just by covering your ears. Some are designed to do this to an extreme degree. For example, in many industrial settings, big noise isolating headphones are required so the workers don't go deaf.
The main advantages of noise isolating headphones is that they're typically cheaper than noise canceling and they're passive. No batteries. Well, unless they need batteries because they're wireless.
Presuming you get a good fit, and they're made to isolate sound, you can get a fair amount of noise reduction with noise-isolating headphones. They're far more reliant on fit, however. A good set of noise-canceling headphones will outperform all but the most heavy-duty noise-isolating headphones, at least when it comes to the situations and sounds where noise-canceling headphones work best. Which is to say, on a long flight NC headphones will offer a greater reduction in airplane engine sound than noise isolating headphones. Standing next to a jackhammer, or a baby, or a baby with a jackhammer, you're going to want some industrial-strength noise-isolating earmuffs.
Shure Aonic 215 noise-isolating true wireless headphones.
The best of both worlds
There is some overlap. If you find a pair of noise isolating headphones that fit you perfectly, they might work better for everything compared to a mediocre pair of ANC headphones. And, as noted above, most noise-canceling models also offer a fair amount of noise isolation (since the former isn't much good without the latter).
The flip side is if you can't find a pair that fits perfect (remember, everyone's ears are different), even an average ANC headphone will likely work better. A general best-to-worst ranking would look something like this:
- Noise canceling (in situations where they work best)
- Noise isolating (good fit and in situations where ANC isn't suited)
- Noise canceling (all situations if you can't get a good noise isolating fit)
- Noise isolating (mediocre fit)
- Noise canceling (bad/cheap noise canceling performance)
The bottom two there are barely better than nothing at all. The trick is finding headphones that fall into the top two categories. Reading spec lists and marketing frustratingly won't help. There is no agreed-upon measurement for noise cancelling. One company's -15dB could be another company's -5dB.
Reading reviews is the best way to get an idea how they sound and perform. And in that, CNET's got you covered. Check out our best noise-canceling headphones, best noise-canceling headphones under $100, the best noise-canceling true wireless earbuds, and the best headphones.
As well as covering TV and other display tech, Geoff does photo tours of cool museums and locations around the world, including nuclear submarines, massive aircraft carriers, medieval castles, airplane graveyards and more.
You can follow his exploits on Instagram and YouTube about his 10,000 mile road trip. He also has written a bestselling sci-fi novel about city-size submarines, along with a sequel.