You would have heard the term “noise cancellation” mentioned in headphones and earphones. Sometimes it is even replaced with the phrase “ANC.”

Such earpieces use engineered noise-canceling technologies to cancel out surrounding noise so you can hear what you want.

Noise cancellation is a broad term, and it denotes various techniques for canceling noise from a stream of sound.

This article discusses some primary noise-cancellation techniques used by headphones and earphones.

What is Noise Cancellation?

Two white guys in band suite putting fingers in their ears to block loud sound
A classic noise-cancellation technique. It never gets old! (Image credit: Chris Fithall)

In simple terms, noise cancellation removes or suppresses unwanted sound from an incoming stream of sound waves.

You can achieve noise cancellation through several methods.

At the macro level, you can cancel noise using double-paned windows, air conditioning units, and soundproofing materials.

But at the micro-level, like in headphones or earphones, it is achieved through soft padding, electronic components, or a combination of both.

Such headphones and earphones use additional microphones to pick up ambient/external noise, which is then analyzed and used to generate a similar sound having reversed polarity (known as anti-noise).

When this generated anti-noise is sent through the headphone speakers, noise and anti-noise cancel out, leaving behind the actual sound one wants to hear.

In most modern headphones and earphones, you’ll find some tiny holes. Sometimes it may be for a microphone, but not always.

Small vent hole on an earpiece
Small vent hole on an earpiece

Are you interested in knowing more about these mysterious holes?

I have written a small blog post about the functionality of small holes in earphones.

Introducing ANC

noise cancellation and ANC
Does ANC always work against noise?

The introduction of ANC technology significantly upgraded noise-canceling technology in headphones and earphones.

ANC is an effective noise-cancellation technique widely used in noise-canceling headphones and earphones.

Note that noise-cancellation is an umbrella term. In addition to ANC, there are also other types of noise cancellations.

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Types of Noise Cancelation and Their Working

Types of noise cancellation chart
ANC is a type of noise cancellation

Active Noise Cancellation (ANC) – How does ANC work?

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  • noise cancellation1
  • noise added with anti noise
  • music noise and anti noise
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    ANC, short for Active Noise Control/Cancellation, is an advanced audio technology that uses microphones to capture external noise and generate inverted sound waves of the captured noise through the headphone speakers to target and remove background noise.

    The newly generated inverted sound wave is called anti-noise, which is used to cancel out the incoming ambient noise through destructive interference.

    Unfortunately, ANC is not a complete solution to noise cancellation as it can only cancel out noise from a constant source.

    Noise-canceling headphones work best in airplanes, trains, buses, offices, or anywhere with constant ambient noise.

    If you are exposed to non-uniform sources of noise like a child screaming, vehicle horns, etc., you will be able to hear some parts of it, even with ANC earphones or headphones.

    But again, the amount of noise cancellation varies in each headphone, and they all don’t work the same way.

    Some expensive ANC-integrated noise-canceling headphones have different settings or modes that allow you to adjust the amount and quality of noise suppression.

    There are primarily three types of ANC. The only difference is how they capture and process the surrounding noise.

    Types of ANC

    1. Feedforward ANC
    2. Feedback ANC
    3. Hybrid ANC

    1. Feedforward ANC

    Microphone setup in feedforward ANC
    Microphone setup in feedforward ANC

    Feedforward ANC is the most used ANC technique on headphones and earphones. In a feedforward ANC configuration, the outside noise is captured using an external microphone and fed to the ANC processor.

    The processor then generates an anti-noise and sends it to the speaker along with the audio one was listening to.

    Here we anticipate an effect and program the processor to counter that, so the chances of errors are high.

    2. Feedback ANC

    Microphone setup in feedback ANC
    Microphone setup in feedback ANC

    Feedback ANC uses a microphone in front of a headphone speaker to record the feedback sample of what a user hears.

    Using this feedback as a reference, Feedback ANC adapts to the noise you hear.

    Here we analyze the effect in real time and use that data to counter noise accordingly.

    3. Hybrid ANC

    Microphone setup in hybrid ANC
    Microphone setup in hybrid ANC

    Hybrid ANC is a combination of both feedforward and feedback ANC. It employs two microphones to analyze the noise.

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    One microphone is in front of the speaker to record the feedback of what the user hears, and another mic is on the headphone’s body facing outward to capture external noise.

    The ANC processor uses input data from both these microphones to cancel noise with higher accuracy.

    Hybrid ANC is rarely used in noise-canceling headphones, but some high-end manufacturers use it on their headphones to give better performance to the user.

    Passive Noise Cancellation (PNC)

    A with noise cancelling earmuffs in a shooting range
    Earmuffs used for hearing protection while shooting is an example of PNC (Image credit: Karolina Grabowska)

    Passive Noise Cancellation (PNC) happens when you close your ear canal with an earplug or finger. It physically shields the outside noise from pushing into your eardrums.

    PNC is known by many names, like Environmental Noise Cancellation (ENC), noise isolation, sound isolation, noise blocking, etc.

    “Passive Noise Cancellation” is a fancy word for physically blocking unwanted sound. Since it can only passively cancel out the noise, it’s called passive noise cancelation.

    Here external noise is shielded from reaching your ear with closed-back headphones that provide good sealing or clamping around your ear.

    Headphones with tight sealing around your ear will, by default, provide some form of physical isolation from external noise. Headphones with soft padding generally are very good at this.

    Adaptive Noise Cancellation

    Adaptive noise cancellation is a technique wherein the surrounding noise is observed in real time to cancel out the noise effectively.

    It is also known as Pure ANC, as it filters out most of the external noise. Adaptive noise cancellation is the best noise-canceling technique, but it’s rarely used.

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    Is Noise-canceling Feature Worth it?

    Advantages

    Some of the advantages of using noise-canceling headphones include

    • Reduced fatigue
    • Improved concentration
    • Increased productivity
    • Reduced stress
    • Great at blocking monotonous sounds

    Disadvantages

    Some disadvantage of noise-canceling headphones is that

    • In most cases, the sound you hear won’t be as crisp as regular headphones or earphones.
    • Some noise-canceling headphones could damage sound quality if there is no noise to cancel.
    • Most noise-canceling headphones will have a strong clamp force causing pain around the jaw and ear.
    • Noise-canceling headphones are power-intensive, so you require good battery backup.

    Conclusion

    noice cancellation in headphones

    In short, noise cancellation reduces the amount of noise that reaches your eardrum.

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    Noise-canceling headphones and earphones are fabulous for people exposed to noisy environments who want to drown out the noise. They can also be used while traveling, where there is often a lot of background noise.

    Though noise-canceling headphones and earphones are not a total solution to noise cancellation, they offer a significant advantage over their generic counterparts.

    All headphones and earphones won’t react similarly to noise. Instead, each will have its limitations and advantages depending on its design and integrated technology.

    To know more about what to look for in a headphone, check out our “headphone selection guide.”

    Frequently Asked Questions

    What does noise-canceling do?

    Noise-canceling is a process that cancels out noise from an incoming stream of sound waves. It can be physical or software-based noise cancellation.

    Does noise-canceling hurt ears?

    No, noise-canceling doesn’t hurt your ears. When you initially start using noise-canceling headphones or earphones, you may hear a slight buzzing sound, but you’ll get used to it eventually. If something is hurting your ear while using headphones, it might be because of the pressure it applies to your ear.

    What is CVC noise cancellation?

    In audio, CVC is shot for Clear Voice Capture. It is a software-based technology that suppresses and filters background noise to capture a person’s voice. CVC technology is mainly used in two-way communication devices like cell phones.

    What are anti-noise and anti-sound?

    Anti-noise is an inverted audio signal of background noise. It is used to filter out noise from an audio output. Anti-sound is a sound produced by the speaker once it receives an anti-noise signal.

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