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What is active noise cancellation? ANC headphones explained

Bose 700
(Image credit: Regan Coule/Tom's Guide)

Many of today’s best headphones don’t just pipe sweet sounds into your ears. They can also listen for and quieten — and even completely silence — outside noises that could disturb your listening pleasure.

But what is active noise cancellation (ANC), and how does it work? In this guide we’ll explain how noise-cancelling headphones and earbuds reduce the volume of ambient sounds, examine whether you should pay more for the technology and take a look at which models are the best at active noise cancellation.

What is active noise cancellation?

What is active noise cancellation

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Active noise cancellation (ANC) is a combination of hardware and firmware that makes outside noises sound quieter when you’re listening to a pair of headphones. Unlike passive noise isolation, which simply muffles those sounds by forming a seal with headphone ear cups or in-ear tips, ANC listens out for these sounds then uses some clever audio trickery to “cancel” them out.

ANC works like this: your headphones have tiny microphones that listen for ambient noise. These aren't necessary the microphones you'd speak into, like on the best headphones with a mic for voice and video calls, but they're still built-in. And the sound they pick up could be anything, from the sound of a passing car to the click-clack of your keyboard.

By picking up these sounds, the ANC system records the sound waves they produce. It can then produce its own sound wave, one of equal amplitude but inverted to the original wave. This creates an interference where the two waves cancel each other out, producing a single, much flatter (and therefore quieter) wave. This resulting wave is then played alongside your music, and because the whole process completes extremely quickly, the original, noisy sound wave never reaches your ear.

If that all sounds a bit complicated, think of it like two boxers hitting a punching bag from opposite directions, at the same time and with the same force: the bag wouldn’t move anywhere. Likewise, the sound waves from outside noise are cancelled out by equal but opposite “anti-noise” waves played by the ANC system.

What is active noise cancellation

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However, there are limits to ANC that make it less effective at silencing certain types of sounds than others. The process is fast but it can’t physically occur in real time, so ANC works best with consistent low-frequency sounds as opposed to higher-pitched, inconsistent sounds like human speech. Vehicle engines and droning air conditioners are easy to cancel out, but the shorter wavelength of high-frequency sounds, like a sudden blast from a car horn, makes it tougher for the ANC’s anti-noise waves to perfectly fill the gaps.

Even so, all sounds will be at least a little quieter when you’re wearing noise-cancelling headphones, and many sounds can be completely silenced even on certain low-cost pairs. The best cheap wireless headphones can certainly count a few ANC models among their ranks

Do I need noise-cancelling headphones?

What is active noise cancellation

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It’s worth clarifying that active noise cancellation doesn’t improve the sound quality of your headphones per se, though it indirectly benefits the clarity of music and podcasts by removing distractions. As such, just about anyone can enjoy the upsides of ANC headphones.

They’re particularly useful for commutes and long-distance travelers, as plane engines and the trundling of trains are exactly the kind of consistent sounds that ANC excels at cancelling out. On an overnight flight, ANC can also help you get some sleep, even if you’re not listening to music.

The most common drawbacks to noise-cancelling headphones is that they usually cost more than headphones without this technology, and the fact that ANC reduces battery life. However, ANC is starting to show up on relatively affordable headphones, such as the JLab Epic Air Sport ANC and the Urbanista Miami. These two pairs also happen to have excellent battery life in their respective classes, so you still find a long-lasting set of cans even with ANC.

One other potential downside to ANC is the reduction in situational awareness; for instance, reducing traffic noise could carry risks if you’re trying to cross a busy street. It’s often harder to tell when someone is trying to speak to you, too. Still, these don’t need to be reasons to avoid ANC headphones. Just exercise caution in situations where your lowered hearing capacity might be a factor — such as if you're out for a run — or simply use your headphones’ ambient/transparency mode. 

Most ANC headphones have such a mode, and it repurposes the onboard microphones to amplify surrounding noises instead of cancelling them out. This is handy for having a quick conversation or giving yourself some extra awareness, and you can switch between ANC and ambient modes at will.

Which noise-cancelling headphones should I buy?

What is active noise cancellation

(Image credit: Regan Coule/Tom's Guide)

In terms of over-ear headphones, our current top pick is the Sony WH-1000XM4. This has it all: highly effective ANC, great overall sound, a comfortable fit and long battery life. It’s also cheaper than our next favorite, the Bose 700 — though the latter makes up for its higher price with noise cancellation that’s even more powerful than the WF-1000XM4. There's a reason the 700 ranks highly on our best wireless headphones and best over-ear headphones lists.

Sony WH-1000XM4: was $349 now $278 @ Best Buy
The Sony WH-1000XM4 is one of the best pairs of headphones overall, let alone one of the best pairs of noise-cancelling headphones, and it's currently equalling it's lowest-ever price.View Deal

Bose 700: $329 @ Amazon
Bose has the best noise-cancelling tech in the game, and the Bose 700 is its finest pair of over-ear headphones. Together, that's an almost essential combination.View Deal

These both sit in the sub-luxury range but there are much more affordable alternatives, like the aforementioned Urbanista Miami and its outstanding 40-hour battery life. The older Bose QuietComfort 35 II also makes a fine choice, if you want high quality without the price of a more recent set.

Urbanista Miami: $149 @ Urbanista
At just under $150, few headphones offer as much as the Urbanista Miami. This is a fun-sounding set of over-ears with great looks, monster battery life and decently effective ANC.View Deal

Bose QuietComfort 35 II: was $299 now $214 @ Bose
This pair of noise-cancelling headphones is just as comfortable as the name suggests, and with Bose-quality ANC and a drastically lowered price, it's compelling for a lot more reasons besides.View Deal

Bose also makes what we think is the best pair of noise-cancelling in-ear buds, the Bose QuietComfort Earbuds. Again, this is a little pricey, but the ANC is impressively adept at cutting out difficult sounds. The Jabra Elite Active 75t is another excellent all-round choice, while the JLab Epic Air Sport ANC and Anker Soundcore Liberty Air 2 Pro provide options at the budget end of the market.

Bose QuietComfort Earbuds: $279 @ Amazon
While not having the secure fit of the best running headphones, the Bose QuietComfort Earbuds successfully squeeze top-quality sound and ANC effectiveness into a compact pair of true wireless buds.View Deal

Jabra Elite Active 75t: was $179 now $139 @ Amazon
The Jabra Elite Active 75t didn't launch with ANC, but had it enabled later via firmware update. Not that you can tell the difference: Jabra's noise-cancelling tech works so well you'd think it was there from the start.View Deal

JLab Epic Air Sport ANC: $99 @ Best Buy
Active noise cancellation, water resistance and a secure fit makes the JLab Epic Air Sport ANC a respectable pair of running and workout headphones. Add in the fact that it only costs $99, and it becomes even better.View Deal

Anker Soundcore Liberty Air 2 Pro: $129 @ Amazon
Another affordable ANC earbud options comes in the Anker Soundcore Liberty Air 2 Pro. In addition to offering several noise cancellation modes to suit your surrounds, this can tune its sound output according to your personal hearing.View Deal