Active Noise Cancellation Explained: What Is ANC in Headphones?

Using active noise canceling headphones to block out industrial noise
Using active noise canceling headphones to block out industrial noise

You’ve seen the term “active noise canceling” being used to promote AirPods Pro and other high-end headphones. But what exactly is it?

When you have no choice but to be exposed to constant ambient noise, active noise canceling (ANC) headphones can save the day (and your hearing!). However, if you’re the type who likes to research before jumping into a trend, it’s easy to get lost in all the technical jargon when reading about ANC.

Unfortunately, not knowing what ANC is all about and how it works can lead to wrong choices. You see, not all ANC headphones perform the same way and can block the same sounds.

But while ANC is technical, understanding its concepts is easy with the right resource. To help you with this, we’ve rounded up all the information you need to know about active noise cancellation. Let’s dive right in.

What Is Active Noise Cancellation?

Active noise cancellation (ANC) is a method of reducing unwanted background sounds to provide a better listening experience by adding a second sound to negate them. And for headphones, this is in the form of advanced technology.

In 1933, Paul Lueg started the theory of noise canceling. Then, Lawrence J. Fogel developed the first ANC headphones in the 1950s. But the type of ANC we know today was developed in 1989 by Dr. Amar Bose of Bose Corporation with the Series I Aviation Headset.

Standard headphones rely on noise isolation from the ear cups or ear tips to block outside noises from your ears. It’s like when you cover your ears with the palms of your hands or plug them with your fingers.

The effectiveness of noise isolation depends on the headphones’ fit and materials. But regardless of the quality, noise isolation only effectively reduces mid to high-frequency sounds by about 15 dB – 30 dB. Higher frequency sounds (think power tools, car engines) can still leak through and pollute your listening experience.

On the other hand, Headphones with ANC use additional hardware and software to actively “listen” to background sounds and nullify them. But what ANC headphones excel at is negating persistent noises, like a running car engine, large air conditioner, and power tools.

ANC headphones essentially combine isolation and cancellation, resulting in an average of 30 dB noise reduction.

However, ANC technology cannot completely block out ambient sounds. Even the highly-praised ANC on the AirPods Max still leaks in sounds. It all comes down to the quality of the ANC system integrated within the headphones.

How Does Active Noise Cancellation Work for Headphones

Active Noise Cancellation uses a combination of microphones, to detect ambient sounds and speakers, to generate an inverted sound wave of the same amplitude.

But these aren’t the microphones you’ll be speaking into when you’re on a call. They are additional microphones located in the ear cups to pick up ambient sounds from outside or inside the headphones.

By picking up these ambient sounds, the headphones record the sound wave they produce and add a secondary inverted sound wave of equal amplitude.

How Active Noise Cancellation works
How Active Noise Cancellation works

When the original sound wave and the inverted sound wave meet, they interfere with each other. This results in a single, much flatter sound wave, which your ears perceive as a quieter sound. That combined sound wave is then played alongside your music or audio on your headphones.

The computational processes happen quickly, so the outside noises will never reach your ears.

You can think of ANC as two boxers hitting either side of a punching bag simultaneously with equal force. Since the forces are equal, the punching bag will not move. You can also think of ANC as adding -2 to +2, which results in zero.

While the concept is the same, there are different ways to construct an ANC system in headphones.

Generally, there are four types of ANC systems:

  • Feedback: This setup has a mic inside the ear cup and in front of the speaker. It allows the headphones to hear what you hear and adapt the noise canceling accordingly. However, it doesn’t work as well for canceling sounds in the 1-2 kHz range.
  • Feedforward: The installed mic is on the outer side of the ear cup. It can pick up external noises quickly and produce anti-noise to counter them.
  • Hybrid: This setup combines feedback and feedforward ANC. It uses two mics: one on the outer side of the ear cup and the other one in front of the speaker.
  • Adaptive: The hardware setup for adaptive ANC is similar to hybrid ANC. But it adds a software processor to adjust the level of noise cancellation automatically based on your surroundings and the headphones’ fit. It was first developed by Qualcomm for true wireless earbuds.
Keen to learn more about the different types of ANC? Read our detailed guide here: The Technology Behind Noise Canceling Headphones.

Active Noise Cancellation Modes in Headphones: Explained

Most of today’s ANC headphones come with additional options that allow users to adjust the settings depending on their needs. There are typically four features or configurations that come with ANC headphones:

  • ANC off: In this mode, you rely solely on noise isolation from the headphones. No anti-noise or anything fancy, but you have a longer battery life.
  • Transparency or Ambient mode: This mode uses microphones to actively transmit background sounds to your ears. Consequently, it allows you to listen to other noises outside your headphones as if you weren’t wearing any.
  • Self Voice: This feature allows you to hear your voice– just like how mic monitoring works in recording studios and games. It feeds your mic’s input into your headphones, which helps when you want to hear your voice’s intonation or volume while you’re on a call.
Not all ANC headphones have the self-voice feature, but the Bose 700 are among the few models that do it very well.
  • Adjustability Levels: ANC that is too intense can result in a vacuum-like feeling in your ears, which is uncomfortable. That’s why some headphones allow you to control how intense the noise-canceling protocol is. High-end ANC headphones like the Sony WH-1000XM5 or Bose Quiet Comfort 45 have this feature.
If you’re thinking of getting a pair of ANC headphones but unsure where to look, check out our recommendations for the best noise-canceling headphones.

How Well Do ANC in Headphones Cancel Sounds?

Despite how far the noise-canceling technology has come, it still can’t block all sounds – especially without playing music. However, that’s not to say ANC is bad at all. In fact, it is much better than just relying on passive noise isolation from headphones.

For context, non-ANC headphones can reduce sounds at mid-to-high frequencies by 15-30 dB depending on the form factor, fit, and ear cup material. However, they can’t reduce low-frequency sounds (20-800 Hz) such as a running car engine, air conditioner hum, or airplane engines.

On the other hand, ANC headphones can typically block an additional 30 dB of low-frequency noises under 1 kHz. This means that ANC headphones can reduce up to 60 dB of ambient sounds depending on the implementation.

But that’s not to say ANC is flawless, though. Since ANC works by recording outside noise and passing it through the system, there’s often a slight lag in the process.

Because of this, ANC works best for reducing repetitive noises, like the constant hum of an air conditioner, rather than sudden loud noises, like an ambulance passing by or a dog barking.

Additionally, ANC frequently has trouble isolating noises from crowded spaces. Human speech is more unpredictable and high-pitched, which the ANC system finds challenging to handle.

But all in all, ANC headphones work well for their intended purpose: reducing unwanted noises.

Exposure to loud noises over an extended period can result in overworking the hair cells in the ear, causing them to die. Worse, there’s no apparent hearing damage until 30% – 50% of these cells die – and once you get hearing damage, it’s most likely permanent.

While the comfort of quiet and peaceful listening is undoubtedly a selling point, ANC headphones also help to minimize the risks of hearing damage.

So, if you’re constantly around loud noises, consider investing in a good pair of ANC headphones.

Is it safe to use noise-canceling headphones? Check out our in-depth article on the safety of noise-canceling headphones.

How can you get better noise cancellation?

If you’re considering getting a pair of noise-canceling headphones, there are aspects that you could look for to find the best option.

The general guideline is to get headphones with excellent ANC and passive isolation. As explained earlier, ANC reduces annoying noise like an AC hum effortlessly. But that’s not the case for sudden loud sounds like gunshots, explosions, or even dog barks.

That’s where passive isolation comes in clutch. The headphones’ ear cups act as physical barriers between your ears and surrounding noises – including loud and sudden ones.

High-quality headphones usually come with ear cups and ear pads explicitly designed to block mid and high-frequency noises.

For the best ANC experience, we recommend getting over-ear or circumaural headphones instead of earbuds. Over-ear headphones have ear cups that completely surround the ears – adding noise isolation on top of the ANC.

Generally, leather-based ear pads work best when it comes to noise isolation. So try to look for headphones with either genuine or artificial leather ear pads for even better noise reduction.


You should now have a better understanding of what active noise canceling is and how it works in headphones.

Did this article help you understand ANC? If not, let us know what other information you’d like to see here in the comments!

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