What is ANC? How the hotly contested headphone tech works

Active Noise Cancellation, or ANC, is the hotly contested feature most headphone spec sheets feature on the current market. Using the magic of audio science to produce an additional sound wave that can cancel out some of the noise of the outside world, ANC headphones or earbuds can help you completely block out external noises and lock into your Spotify Daylist or favorite podcast.

Of course, ANC isn’t perfect, and you won’t be able to completely isolate yourself from external noises, but ANC can make a significant difference and allows you to enjoy audio with minimal distractions. In fact, some ANC headphones and earbuds — like the Bose QuietComfort Ultra earbuds — are so good it’s almost too isolating.

But how does ANC technology work to actively keep your music in, and you tuned out of external distraction? Read on for what you need to know.

How does ANC work?

Standing for Active Noise Cancellation, ANC, the technology works to block out external sound from getting to your ear using built-in microphones to listen to the surrounding environmental noise. The ANC tech then creates an equal, but opposite sound wave to counter the envrionmental noise, and therefore flatten the wave or cancel it out.

This method is known as “anti-noise” and it works best when eliminating steady and constant low-frequency sounds like the hum of a fan, because it’s easy to counter with the opposing sound wave. When there are sudden noises, the sound may reach your ear before the opposing sound wave can be generated, so some of the noise will still get through.

How does ANC differ from passive noise cancellation?

With many over-ear headphones, you also benefit from passive noise cancellation, where some external noise is blocked out by the cushions of the headphones.

Physical noise blocking also occurs when you have a good seal around the ear or ear canal. This is why you’ll find high-quality in-ear headphones that have a custom-fit tip design that’s crafted to fill the ear stop noise from the outside world entering your ear canal. This way, you can focus more on your favorite tunes or podcast.

Why you may prefer Active Noise Cancellation…

Passive noise cancellation can only do so much though, which is where active noise cancellation comes in. Active noise cancellation uses a combination of hardware and software to eliminate environmental noise like the hum of an airplane engine, the sound of fans, or the constant white noise of an air conditioner. Good ANC can also block out people talking, the sound of passing cars, and more, although no ANC system will completely isolate you from all outside noise.

The 3 different ANC types

There are several different types of ANC that are used in ANC headphones. Some products use a single method, and others use a hybrid system in order to try to reduce as much noise as possible.

1. Feedforward ANC

Feedforward ANC uses microphones that are built onto the outside of the headphones. These microphones pick up the noise from the outside world and use it to generate the anti-noise that will significantly reduce the noise that they pick up. This type of ANC is ideal for earbuds, which don’t have a huge amount of room to fit additional microphones inside the ear. The Jabra Elite 4 earbuds are an example of headphones that use feedforward ANC.

Jabra

2. Feedback ANC

Feedback ANC uses microphones located within the cup of over-ear headphones, or within the ear itself when using earbuds. The benefit of placing the microphones on the inside rather than the outside is that they pick up the noise as it reaches the wearer’s ear, so it more accurately reflects what the wearer is hearing, since the sound has already passed through the material of the headphones. However, feedback ANC is susceptible to high-frequency external noise and can sometimes generate feedback that makes external noise louder rather than quieter.

3. Hybrid ANC

Essentially, Hybrid ANC is the best of both worlds. It combines both feedback and feedforward active noise cancellation by using microphones both on the exterior and interior of the headphones. This means that hybrid ANC headphones can cancel the majority of the noise that reaches your ears as well as high-frequency noise that the interior microphones may not pick up. Since it requires more microphones, headphones that offer hybrid ANC are often more expensive. The AirPods Max, for example, are headphones that employ hybrid ANC.

Will ANC block every sound out?

Because it works best with constant frequencies and sound waves, you’ll find that active noise cancellation isn’t able to block everything out. You’ll still hear some sounds when using ANC headphones or earphones.

Why are ANC headphones worth it?

You’ll often hear people recommend active noise cancellation for commuting.

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If you’re regularly on a train or a plane, then an ANC-equipped headset can be a great investment, especially if you’re trying to sleep or just don’t want to put up with the constant noise around you. ANC is also great if you just need to block out the world and concentrate.

Does ANC drain my battery?

A drawback is that ANC requires power in order to work. This can mean that the batteries drain faster, and you’ll need to charge your headphones more often than a pair without ANC. However, many ANC headphones have decent battery life, and are worth considering when buying a new pair of headphones.

What is transparency mode?

Sometimes. when you’re wearing your headphones you will want to hear what’s going on around you. Whether that’s to listen to someone talk more clearly or just hearing your surroundings for safety, there may be times when you want the active noise cancellation to stop briefly.

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This is where transparency mode comes in. Instead of canceling the noise of the outside world, transparency mode enables you to hear more of the outside world without taking your headphones off. It can even enhance speaking voices, making them clearer to hear. Transparency mode is available on Apple AirPods, but similar options are also available on other headphones with ANC.

Are ANC headphones safe to use?

Blocking out the sounds of your surroundings comes with some risks. You won’t be able to hear what’s going around you as clearly, which has some potential dangers. When you’re crossing a road, for example, you may not be able to hear cars approaching, especially the low hum of electric cars.

However, some key noises will still come through. If someone is shouting to get your attention, for example, or beeping their horn at you, that noise is unlikely to be completely blocked out. You just need to be mindful to use ANC carefully so as not to put yourself at risk.

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If you’re looking for headphones for working out outdoors, you may prefer something at the opposite end of the spectrum. Bose Open Earbuds, for example, are designed to allow more of the outside world in, not less, so they could be a good choice for your workout headphones.