What is Active Noise Cancellation (ANC) in Headphones?

Active Noise Cancellation (ANC) in Headphones

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Modern headphones boast superior sound reproduction and other powerful features.

Active noise cancellation (ANC) is one of those standout traits. Essentially, ANC makes outside noise quieter or even cancels it out completely.

In this post, I’ll try to clearly explain more about active noise cancellation and how this technology ensures a better listening experience overall. 

Basically, shut out the noise and focus on the music.

What Is Active Noise Cancellation?

ANC combines software and hardware to lower external noise in your headphones while listening to music or making a phone call. The system picks up sounds from the background and actively cancels them out.  

Active noise canceling should make the headphones sound clearer and noise-free.

How Does ANC Work?

The headphones need special built-in microphones for active noise cancellation to work correctly. 

These microphones differ compared to regular voice mics. Their intended use involves something other than catching the frequencies of the human voice. 

Instead, these microphones are designed specifically for constant noise, predominantly.

The built-in microphones are embedded into the headphones and are usually hard to spot. In some models, they may be completely invisible. 

c side view
Bose QuietComfort 35 ANC Headphones | Make Life Click

They catch ambient sounds and forward them to the ANC system, which records the noise.

The system then creates a corresponding sound wave with the same amplitude but out of phase by 180 degrees (π radians, or half a wave cycle) compared to the recorded sound. 

In other words, the reproduced wave has peaks where the original has valleys and vice versa.

The resulting sound interference makes the original waveform flatter, i.e., quieter. The headphones play the interfering sound wave simultaneously with your music or whatever you’re listening to, keeping most of the original noise from reaching your ears.

The entire process may sound complex, but the digital system works at extreme speeds, making the effect almost instantaneous.

The Difference Between ANC and Other Types of Noise Cancellation

Active noise cancellation isn’t the only technology used in headphones to neutralize outside noises. 

There are two other types: passive and adaptive noise canceling.

Passive noise cancellation represents the basic, most straightforward solution. It relies on a physical barrier to block outside noise. Headphone pads and foam in-ear tips are typical examples of this technology. This noise cancellation depends on the quality of the seal.

Adaptive noise cancellation is on the other side of the spectrum from the passive type. It uses active noise cancellation as the base but adds powerful algorithms for advanced noise detection. As a result, this system can provide near-perfect results.

ANC falls between the two other types and may represent the best noise-cancellation solution for most users. Quality ANC headphones will cancel noises more reliably than most passive systems. 

On the other hand, adaptive noise cancellation might be overkill for everyone except people working in boisterous environments or traveling a lot. 

Personally, I love ANC headphones for travel and the office but less so at my desk or living room at home. 

ANC has three variants, making each useful for different situations.

Understanding the Three ANC Types

The variants of active noise canceling technologies are feedforward, feedback, and hybrid ANC

All three variants use the same methods but differ significantly in their implementation.

Headphone component
Bose QuietComfort 35 component | Make Life Click

1. Feedforward ANC 

In this technology, the microphones are installed on the outside. The mics “listen” to sounds from the surrounding, maps them, and forward the waves to the system for processing. 

This variant is most suitable for earbuds which often lack sufficient space for microphones on the inside.

Feedforward may not provide the best noise cancellation since it lacks the accuracy of other methods. Plus higher frequencies can bleed through depending on the headphone or earbud fit.

However, this system has certain advantages, as it can pick up specific, mid-frequency sounds like traffic noise and speech, making it suitable for general use.

2. Feedback ANC 

This technology utilizes microphones placed on the inside. The advantage of this system is that it isolates the sounds passing into the wearer’s ear. 

This ensures better accuracy as most of the noise you would otherwise hear gets captured and canceled.

The downsides of the feedback system relate to high-frequency sounds and the audio coming out of the headphones.

Firstly, less high-frequency noise passes the headphone cups, making the microphones less sensitive to that particular range. Lower sensitivity means that feedback ANC users could face the same issues as feedforward users.

Secondly, the feedback system has to account for the sound produced by the headphones, as the mics will also pick that up. The system is under additional strain because it has to perform additional filtering and frequency corrections.

3. Hybrid ANC

This represents a combination of the previous two systems: it has both inside and outside microphones.

Unsurprisingly, this is the best noise-cancellation option of the three as it offers the most benefits, which include:

  • Covering the most extensive frequency range
  • Minimizing feedback chances
  • Ensuring near-ideal isolation
  • Providing high ANC accuracy

The downside of hybrid ANC is the same as with most advanced technology – it’s pricey.

First, there are more microphones in the headphones, but their quantity is one of many aspects affecting the cost. The mics also have to be high-quality to perform their function well. 

Also, the higher microphone count necessitates more processing power. 

Finally, the performance requirements mean more testing, which creates an additional production expense.

Do You Need Active Noise Cancellation?

Noise cancellation can be very convenient for all headphone users who want more unaffected listening experiences. 

OneOdio A10 headphones headband
OneOdio A10 Headphones | Make Life Click

However, it’s worth noting that active noise cancellation has limitations.

For example, although noise canceling is relatively fast, it doesn’t happen in real time. 

As a result, the system will be more reliable with droning, persistent sounds but may struggle to isolate inconsistent noises. In other words, ANC doesn’t guarantee perfection. 

Still, even the most basic feedforward ANC should provide better sound quality than models with passive cancellation, depending on the construction of the particular product.

ANC can also stifle external noise more than passive headphones. 

As a result, you might miss important cues from surrounding traffic. It may also be harder to spot someone talking to you. 

Higher-quality ANC headphones like the QC35, QC45, and Sony WH-1000XM4 have a transparency mode to shut off ANC or a mode that amplifies incoming non-background noise, but they usually come at a premium.

It’s pretty important to approach headphones with active noise cancellation with an understanding of the technology and realistic expectations. If you want to listen to music with fewer distractions, a pair of quality feedback or hybrid ANC headphones will be the best choice. 

However, professionals working in loud environments, travelers, and noise-office types would benefit from adaptive noise cancellation. If you fit any of those situations, it’s pretty cool how quiet your surroundings can be.

A passion for writing and ongoing research projects gives Catherine an incredibly broad knowledge of all things. She has authored an incredible number of articles and can be found in the wilderness when not attached to technology or listening to podcasts.

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