What is Noise-Cancelling, How it works in Headphones? (PNC & ANC)

Noise Cancellation


Noise cancellation is the phenomena of cancelling or muting the unwanted noise of the background to have a better experience while enjoying content on headphones.

The discovery of noise cancellation was done by Paul Lueg in the year 1933, he realised that he could cancel sounds of a loudspeaker by using phase advancing waves, which causes interference with the sound produced by loud speaker.

This discovery led to the Active noise cancellation we know of today.

Types of noise cancellation

There are three types of noise cancellation:

  • Active Noise Cancellation
  • Adaptive Noise Cancellation
  • Passive Noise Cancellation

People tend to mix these terms, though the goal is same of all three techniques but the way the achieve it is different and also differ in the effectiveness.

Noise cancelling in Hammer Headphones

ANC or Active Noise Cancellation

Active noise cancellation is a very sophisticated technology. It detects the ambient noise in the room with the help of microphones. This detected noise is then analysed and its sound wave and magnitude is identified. After that the system generates the same sound but in opposite phase so as to cancel the ambient noise. This antiphase noise is fed into headphone with the music and it cancels the effect of ambient noise and the user only hears the music.

Adaptive noise cancellation

This is the latest type of noise cancellation technology. It is basically an improvement of Active Noise Cancellation.

In this technology the basic principle of noise cancellation is same, the ambient noise is cancelled with the anti phase noise built by the system but it adds advanced algorithms and more mics to the system to produce nearly perfect anti phase sound to cancel the ambient noise.

It has mics mounted inside the headphone also which detects the noise leakage due to hair, shape of the ear, glasses and fit. With the help of it they try to maintain the best music listening experience possible.

Also, they compare the input audio source with the output audio signal to make sure that noise cancellation algorithm is not interfering with the music produced.

PNC or Passive Noise Cancellation

This is the simplest and most cost-effective type of noise cancellation and also is better known as noise isolation.

In this method headphones do not generate any opposite phased sound waves instead they block outside noise physically by the use of headphone cushions, sound reflecting materials etc.

There are many methods to achieve noise isolation or passive noise cancellation but the central idea remains the same i.e., physically blocking the sound from entering the ear.

Over the ear headphones achieve this by using their foam/cushion as a seal which wraps around the ear and stops sound from entering the ear canal.

Some earbuds achieve this by using their silicone tips to make a seal with the ear and stop other sounds to enter the ear.

Headphones and earphones are trying to achieve a similar effect but they take it a notch higher. Some, designed to work in-ear, are made up of foam that can be squeezed so as to make a perfect seal with your ear canal.

They also combine acoustic materials to reflect the sound and foams and cushions to achieve the goal of eliminating noise.

The effectiveness of this technology depends on the quality of materials used and the ability of acoustic engineer to design the headphone such that it doesn’t allow external sounds to enter the ear.

What type should you go for?

Going with either of three is not a wrong choice, it all depends on your requirements, your budget and the environment you are going to use it in, is it extremely noisy or not.

Sometimes passive noise cancellation works great for example if you are going to use your headphones in your room where not a lot of noise is present, they work just fine but if you work on a construction site where industrial tools are being used continuously you might need to get a good pair of Active noise cancelling headphones and if you are in an environment where a lot of different changing noises are there, you might need to get adaptive noise cancelling headphones.

So, this way depending upon your circumstances you can choose the type of noise cancelling technique you need to go with.