What is ANC – How Does Noise Cancellation Work in Headphones?

If you spend time outside in a bustling city or even indoors with a lot going on, it’s hard to have any moments of peace. How do you focus on work or listen to music peacefully with so much going around you?

Enter noise-cancelling headphones.

They are built with technology to cancel out surrounding sound and put you in a noise-free zone where you can listen to your favourite music peacefully.

Sometimes noise cancelling sounds too good to be true. How does it actually work? We were just as confused, so let’s explore everything behind the technology they use.

History of Noise-Cancelling Headphones

Noise cancelling is a recent technology that has only been perfected in the last decade. Before this, the only form of noise reduction in headphones was passive noise isolation. The build of some headphones and earphones is such that they help isolate outside noises. This enables you to get a peaceful listening experience.

Passive Noise Isolation

The first ever passive noise-isolating headphones date back to 1891. This was when French Engineer Ernest Mercadier designed something similar to today’s in-ear earphones. The rubber tips on them were identical to silicon buds today and created a seal inside the ear that helped isolate outside noises.

First ANC Patent

Dr. Lawrence Fogel brought the first idea of active noise-cancelling headphones. He even submitted patents by the 1950s. He designed these noise-cancelling headphones especially for pilots so they could communicate better and protect their hearing because of the reduced sound.

First Commercially Available ANC Headsets

This technology was only restricted to professionals until Amar Bose in 1978. Amar was taking a flight from Zurich to Boston. He was frustrated that the noise of the air jet was cancelling out all his music.

It took Bose Audio some time to develop them, but they finally came out with the world’s first commercially available Noise Cancelling headphones in 1989.

To understand how noise cancelling works, let’s start from the basics and understand how sound works. This will make it easier to understand the technology noise cancelling headphones use.

What is Sound?

Sound is a form of energy that travels through different mediums. It causes movement as it travels through mediums (in our case, air), so the sound can eventually get to us, and we can hear it.

All sound travels in the form of waves, and every sound wave differs according to pitch, loudness, and several other factors. Each sound wave is made up of peaks and valleys, similar to how sound travels through the air in a series of compressions and decompressions.

If we were to illustrate sound waves, they would look something like this.

Sound Waves

Now that we know how sound works, let’s see what noise-cancelling headphones do to cancel them out.

How Does Noise Cancellation Work in Headphones?

Noise-cancelling headphones have built-in microphones to pick out surrounding sounds. They use something known as destructive interference.

As we discussed earlier, sound waves have both peaks and valleys.

Destructive Interference

If this is combined with a sound wave that is the opposite, has a peak for every valley of the other sound wave, and vice versa, this cancels out both sounds and flattens the sound wave. What ensues is total silence.

Noise-cancelling headphones have microphones to pick out surrounding sounds and create a sound that is the opposite of them. This waveform of the opposite sound is combined with the audio you are playing through your headphones.

When you listen to this combination, you can only listen to your audio, and other noises are drowned out.

What are the Different Components of Noise-Cancelling Headphones?

Here are all the components inside noise-cancelling headphones that make noise cancelling possible.

• Microphones – Noise-cancelling headphones have microphones on the outside of ear cups to pick up environmental sounds. Headphones usually have two or more microphones to pick up sounds from different places. Earphones usually have these microphones placed in their stem.
• Noise-cancelling circuitry – The sounds picked up from the microphones are analysed in their frequency and wavelengths. They use these pre-existing sound waves to create new waves that are the opposite and will cancel them out.
• Speaker – The new sound waves created to cancel out outside noise are combined with the audio playing in the speakers. This combination eliminates outside noise and keeps the normal audio intact.
• Battery – Noise-cancelling headphones utilise extra energy to run the noise-cancelling effect. This is the reason why noise-cancelling headphones run out of charge faster. They use the rechargeable battery of the headphones to run.

Can Noise-Cancelling Headphones Block Out all Noise?

Unfortunately, no. Active noise cancellation is effective for low-frequency, repetitive sounds, such as the sounds of an aircraft or the AC unit in your office.

Since the sound is so repetitive and consistent in these situations, they only have a few hundred peaks and valleys every second.

High-frequency sounds have thousands of wavelengths per second and don’t have a repetitive pattern. This makes it harder for your headphones to create opposite sound waves.

This is why even if you have the best ANC headphones out, some ambient noise will still get to you, such as the sounds of people talking or something unexpected like a car honking.

Pros and Cons of ANC Headphones

Here are some of the advantages and disadvantages of using noise-cancelling headphones.

Pros

Helps You Concentrate

It goes without saying that you won’t be able to concentrate on work if your neighbours have suddenly decided to rebuild their house and now you can’t escape the sounds of sledgehammers.

A lot of us have no choice or control over our environment. What happens when we are exposed to sound?

Research shows that constant noise exposure affects cognition, hinders learning ability in things like studying and work, and disturbs sleep.

This is where noise-cancelling headphones come in clutch. Even if you can’t control the environment around you, you can block out sounds that are keeping you from concentrating.

Improves Your Audio

Ever tried listening to music in a crowded cafe where the sounds of people talking keep drowning out your music? Or worse, you’re in an aeroplane.

There’s constant sound from the aircraft engines, the background noise of people talking, and the occasional baby crying. No matter which movie you put on to watch, you won’t be able to follow along without subtitles.

Any music you try to listen to will also get drowned out. Now imagine noise-cancelling headphones in this scenario. While they won’t block out every noise, they cancel enough so you can hear your music clearer than before.

Have Clear Calls

Since the pandemic hit, we have become all too familiar with having meetings as a part of working from home. While some people have separate home offices, not everyone has access to them.

This is especially a nightmare when your boss is talking about something important you can’t hear. Or you’ve already repeated the same thing three times, and there’s awkward nodding from the other side because no one could make out what you just said.

This is also an area where Noise Cancelling headphones come in handy. Noise cancelling during calls is a feature not available with every noise-cancelling headset, so research beforehand.

Some noise-cancelling headphones will activate ANC during calls to reduce background noise and help you listen to the person you’re talking to, even in crowded places.

You can also download additional apps to help cancel out background noise from your audio, so whatever you say gets heard clearly.

Cons

They are Expensive

If you want a high-quality pair of noise-cancelling headphones, they’ll definitely burn a hole in your pocket. While manufacturers are trying to make them as accessible as possible, like with the new Sony WH-CH720N, they still come at a steep price when compared to regular headphones.

If you’re not ready to make the investment yet, you can explore headphone and earphone options that come with passive noise cancellation. They will reduce background noise to some extent compared to regular headphones.

Make you Unaware of Your Surroundings

Noise-cancelling headphones are great when you’re stationary but pose potential harm if you’re walking around with them. They make you unaware of your surroundings and drown out oncoming traffic sounds.

Some headphones also come with different ANC modes, such as an ambient mode that lets some sound through. Keeping your headphones on is still not a good idea if you’re walking down a busy street.

Shorter Battery Life

Noise-cancelling headphones use a lot of power because of all the behind-the-scenes work they do of picking up audio and synthesising different sound waves to cancel them out. These headphones consume a lot of battery in a relatively short time.

The battery life will be even shorter if you’re looking at wireless earphones with ANC.

The shorter battery life will be an inconvenience if you need to keep travelling and want to avoid having a second device to charge constantly apart from your phone.

Conclusion

If you spend any amount of time in noisy environments and find it hard to concentrate on work or play, noise-cancelling headphones are going to be a potential lifesaver for you.

We hope this article helped you unravel the mystery behind how they work and all the possible things you need to keep in mind before getting a pair for yourself.

They come with advantages and disadvantages, so do thorough research before making your decision.