How Does Noise Cancelling Technology Work?

Image of Noise Cancelling Diagram

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The history of noise cancellation technology dates back to 1930s when a German inventor registered a theoretical patent for canceling noise by using interference and creating ‘zone of quiet.’

Today, the theory serves its purpose right. Whether in the field of military and civil aviation or merely in the arena of music listening, noise cancellation technology has been a great deal for many.

How does noise cancellation technology work?

The family of noise canceling technology comes with twins. And just like identical twins, they may look the same, but they aren’t. These noise-canceling headphones come in two types.

Passive Noise Cancellation

Passive noise cancellation technology relies on the physical design of the earcups. The fit and the shape of the earcups determine the extent of the headphone’s power to block ambient noise.

Circumaural headphones are the best type of passive noise canceling headphones. It’s the most widely used in the market. They’re large and fit entirely to the ears. They seal the ears from unwanted outside noise. Neither earbud headphones or supra-aural headphones offer the work that circumaural headphones do.

Active Noise Cancellation

Compared to the prior, active noise canceling headphones rely upon its electronic circuitry to provide noise cancellation. ANC is about generating ‘anti-noise’ that mirrors and cancels the ambient noise.

In an illustration below, notice that the waves that come from the headphones and the external noise have the same amplitude and frequency. But their crests (compressions) and troughs (rarefactions) are designed that the crests of one wave complement with the trough of the other wave. Think of adding 2 to -2. This phenomenon is known as destructive interference.

For a successful noise cancellation, various components are valuable.

1. Microphone
Located inside the earcup, the microphone ‘listens’ to external sounds that can’t be blocked passively.

2. Noise-canceling circuitry
The electronics in the ear cup help sense the input from the microphone.

These electronics generate ‘fingerprints’ of the noise. This mechanism allows the device to note the frequency and amplitude of incoming waves. Once they’ve created a ‘fingerprint’ of the ambient noise waves, they create a new wave that’s 180° out of phase with the waves associated with the noise.

3. Speaker
The headphone’s speakers receive the ‘anti-sound’ feed created by the noise-canceling circuitry along with the standard audio. As the anti-sound erases the noise, it doesn’t affect the sound waves in the regular audio.

4. Battery
This component is the powerhouse of the entire noise canceling scheme. It gives essence to the word ‘active’ in ANC since it supports the system to produce a noise-canceling effect.

With the help of these components, the noise-canceling headphones may reduce the noise for up to 20 decibels. At this rate, noise-canceling headphones may be ideal for flights and train travel since they may block 70% of the ambient noise. They’re also suitable for open office environments or any other places with high level of ambient noise.

In an ideal world, noise canceling headphones allow you to have a noise-free music experience. But in reality, that world doesn’t exist. There are trade-offs. But no matter how noise canceling tend to disappoint those who expect too much from its technology, the users can’t get enough of the promise that these headphones bring.