What is ANC and how does it improve my headphones? – Review Geek



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Headphones and earbuds used to be pretty basic. They had only one job: to make music. But a relatively new feature called ANC or “active noise cancellation” has turned everything upside down. It is now impossible to buy headphones without encountering this feature, which claims to reduce background noise in any environment. And let me tell you, ANC is awesome.

Here’s the problem; ANC headphones or earbuds often cost a lot of money, and no one wants to spend extra on something they don’t understand. Therefore, it is time to learn how ANC works and evaluate any limitations or problems you may encounter when using ANC.

What is Active Noise Canceling?

Since headphones and earbuds cover your ears, they all offer some degree of noise cancellation. But this “passive” cancellation isn’t very effective, especially if you’re on an airplane, in a noisy office, or next to an air conditioner.

And that’s where ANC or “active noise cancellation” comes in. Headphones or earbuds with ANC don’t just cover your ears; they also use digital processing to suppress background noise. The result is truly amazing, as ANC can instantly turn a noisy environment into a quiet haven.

Most high-end wireless headphones and earbuds now come with ANC, although the feature tends to work pretty well even in affordable products. Additionally, some headphones and earbuds allow you to adjust the ANC intensity via an app, which is a handy feature if you only want to cancel certain sounds.

If you ever find yourself in a noisy environment that is uncomfortable or disruptive, ANC is an essential feature to look for in a new pair of headphones. But how does ANC work, and is it always a good thing?

How does active noise cancellation work?

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You probably know that sound, like light, travels in “waves”. And while light and sound are two very different things (light is radiation, sound is pressure), their respective waveforms work in similar ways.

We are going to focus on the waveform frequency as that is the most important part of understanding ANC. In unscientific terms, frequency is the speed at which a wave shakes. For example, low-frequency light waves are red, and low-frequency sound has a low pitch.

Oddly enough, low-frequency waveforms are also very good at traveling through space. That’s why the sky looks red at night. And unfortunately, it’s also why your neighbor’s music booms through your house. Old-fashioned headphones can ‘passively’ block high-frequency sounds, but they can’t protect your ears from low-frequency noise, hence the need for something as sophisticated as ANC.

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Now that you know a bit about waveforms, the science behind ANC is actually quite simple. Basically, headphones or earphones with ANC use microphones to pick up external noise. Then they reverse the polarity of this sound (they flip the waveform upside down) and pump it into your ears. Since sound is a form of pressure, the “anti-noise” wave physically cancels out any unpleasant background noise that manages to penetrate your headphones.

The efficacy of ANC headphones or earbuds may vary depending on the design. For example, high-end headphones can use external and in-ear microphones. The external microphones allow your headphones to respond quickly to noise, while the in-ear microphones can “hear” any low-frequency rumble that manages to reach your ears. (Some headphones use in-ear microphones to detect if an ANC signal is malfunctioning.)

Earbuds rarely have room for in-ear mics, so they tend to be less accurate than full-sized ANC headphones. So ANC earbuds can react quickly to external noises, have a harder time canceling low-frequency rumble and can’t correct themselves if something goes wrong.

Does ANC affect sound quality?

Sony

Unfortunately, you can’t use ANC without sacrificing some sound quality. The technology isn’t 100% accurate, so you can expect a slight hissing sound when you activate ANC on most headphones or earbuds. You will also notice a decrease in sound quality if the headphones cannot create a good seal over your ears.

And if you’re a born audio tracker, you may notice a change in sound quality when you activate ANC. That’s because your headphones need to add an “anti-noise” ANC signal to your music, which requires digital processing. While this processing shouldn’t harm your music, it does require additional power consumption, which can cause problems.

In wireless headphones or earbuds, using extra power will significantly reduce battery life. Manufacturers are forced to share the difference. Otherwise, customers will complain that their headphones don’t work long enough. So when ANC is active, the drivers in your headphones get less power, which reduces dynamics and frequency range, but extends battery life.

Headphones and earbuds usually apply an EQ to music when ANC is active, which can counteract the change in audio quality. Often this trick doesn’t work, although high-end headphones that go through a lot of development can sound the same whether ANC is active or not. (The change in audio quality is most noticeable in budget earbuds, mainly because of cheaper hardware and a lack of R&D.)

By the way, wired headphones are not free from this problem. Most wired ANC headphones contain a battery, as the “passive” signal from a 3.5mm cable cannot power a digital audio chip. When this battery is activated, the amount of power available to the headphone drivers changes, changing their sound profile.

Are ANC Headphones Comfortable?

Apple

When people first try ANC, they may feel a strange “pressure” on their ears. It’s a weird phenomenon that can be painful for some people, although it usually goes away once you get used to the feel of ANC.

As with all things in life, the human brain is responsible for this problem. Our brains rely in part on our ears to detect changes in air pressure, so when an ANC headset suppresses a rumbling sound (especially one that is loud and persistent), it can trick our brains into thinking the air pressure has suddenly changed.

People usually pop their ears to accommodate shifts in air pressure. But this doesn’t change the feeling of wearing ANC headphones. As a result, you may feel a little uncomfortable while using ANC.

Again, this problem usually goes away once you get used to wearing ANC headphones or earbuds. But some people just aren’t made for ANC. Fortunately, the ANC mode on your headphones is optional, so you can turn it off at any time.

The opposite of ANC: transparency mode

All current-generation AirPods models support Transparency mode. Justin Duino

Now that ANC is a relatively common feature, headphone makers are looking for other ways to make their products stand out. A new feature, which is actually the opposite of ANC, is usually called Transparency or Ambience mode.

Transparency mode picks up external noise and pumps it into your ears so you can hear your surroundings. It may not sound intuitive, but Transparency mode can help you avoid unwanted or dangerous situations when you’re walking outdoors, going to the gym, or traveling on public transportation.

This feature isn’t just for security, of course. You can use Transparency mode to hear, for example, family or friends without pausing your music. I actually use it while cooking as I can hear the food sizzling in the oven or simmering on the stove.

I should also mention that, like ANC, the transparency mode is usually adjustable. In some cases, headphones or earbuds even have a Transparency setting that focuses on voices and ignores other outside noises.

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