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What are noise cancelling headphones?

Noise cancelling headphones
(Image credit: Getty)

It’s all very well having a five-star pair of headphones to liven up your commute, but if all you can hear while you’re wearing them is the screech of the train and the honking phone conversation of the tedious ego in a suit next to you, you’ll soon begin to think your money might’ve been better spent on a good pair of earplugs.

Just turning your music up to drown everything out is what your doctor might describe as A Bad Idea, plus it could easily annoy the person on the other side of you to the bellowing dullard. In the interests of your own hearing, what you need is a pair of noise-cancelling headphones.

Active noise-cancelling (sometimes referred to as ANC) uses built-in microphones to listen to the world around you and filter out as much racket as possible, leaving you in your own little oasis of calm. They’ll never block out absolutely everything – at least not yet – but a good pair can remove the general low-frequency drone of everyday life, meaning you can listen to your tunes at a lower volume. 

Without wanting to get too techy, these wired and wireless headphones work by creating a sound wave that’s inverse to the one coming from outside, which when played through your headphones negates the racket around you. That means they’re more effective at dealing with constant, predictable hums than erratic, spontaneous crashes or bangs, meaning you should still hear if a meteorite lands next to you at the bus stop.

It does also mean that having noise-cancelling turned on can affect the performance of your headphones and change the way your music sounds, so be careful when picking out a cheapo pair that seems too good to be true. 

More advanced pairs, such as B&W’s PX and Bose QuietComfort 35 II offer more than just on and off when it comes to their noise cancelling, with different settings available for different environments, allowing for more or less sound to be let in depending on how willing you are to be disturbed. It’s all very well wearing a pair in the office, for example, but your colleagues won’t be so keen on your new headphones if you can never hear them when it’s your turn to make the tea.

To get around this, the PX and Sony’s WH-1000XM3 headphones allow you to briefly change the job of the built-in microphones, using them instead to pipe in outside noises, such as train station announcements or enquires from cabin crew when you’re onboard a plane. 

B&W PX

The B&W PX in action.

Speaking of air travel, differences in atmospheric pressure can also affect how things sound, so the Sonys also adjust how their noise-cancelling works when at altitude to make sure they block out the drone of the plane’s engines as effectively as possible.  

All of this requires power to work, as does the Bluetooth connection to your phone, but when the battery dies, some pairs will allow you to plug in a cable to keep listening, you just lose out on their ANC skills.  

That doesn’t necessarily mean you have to hear every crash, bang and wallop around you though. If your headphones completely cover your ears, there’s an element of acoustic sealing going on that’ll keep out some sounds in the same that way that clamping your hands over them would, it’s just nowhere near as advanced as using ANC.

That means pairs of headphones without ANC can still offer a level of noise reduction, but they do so without using any fancy electronics, instead relying on physically blocking out the sounds like a good old-fashioned pair of earplugs. That’s why a snug-fitting pair of in-ear headphones will offer much more blockage than a pair of folding cans that just sit lightly on your ears.

Pairs of ANC headphones do still tend to be over-ears, though, mainly because it allows for more reliable acoustic sealing, which makes the noise-cancelling more effective, plus there’s space for a bigger battery. 

If you’ve been convinced by the ways of the quiet, here’s our pick of the top noise-cancelling headphones available.

Black Friday music deals are fast approaching. Keep your eyes peeled to our Black Friday wireless headphones deals page for the very latest offers on in-ear, on-ear, wireless and noise-cancelling headphones.

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