How Do Noise-Canceling Headphones Work?

Whether you’re on board an aircraft or you’re in an open space, noise-canceling headphones have been our best weapon to fend off those pesky outside noises. But have you ever wondered what’s the magic behind this technology?

Know that noise-canceling headphones come in two forms…

• Active
• Passive

Passive Noise-Canceling Headphones

Technically, any pair of headphones is capable of passively canceling out ambient noise to some degree, due in large part to their design and the materials they are commonly made of. Over-ear headphones, or circumaural in techspeak, often come to mind.

Over-ear headphones have ear cups, which are stuffed with layers of foam, that fully enclose your ears. Just by its design, you can tell this kind of headphones can prevent background noise from penetrating your ears, reducing noise by about 15 to 20 decibels (dB).

Aircraft or subway noise can be as loud as 105 dB, thus ordinary over-ear headphones just won’t cut it.

This is where “active noise-canceling” or ANC headphones come in.

Active Noise-Canceling Headphones

Often referred to in the industry as simply “noise-canceling headphones”, active noise-canceling headphones are engineered to electronically block ambient noise for a smoother undisturbed sound experience.

Bose’s branding heavily relies on its noise-canceling technology, setting itself up as the company to beat in that department, and its QuietComfort series is widely known to be the best among audio circles.

Then there’s Sony MDR-1000X, a pair of badass ANC wireless headphones that will give Bose QuietComfort owners a run for their money.

So next time you bump into a pair of headphones described to have a noise-canceling technology, it usually means active noise-canceling headphones.

How Do Active Noise-Canceling Headphones Work?

But what’s the technology behind it all? Let’s crystallize it in simplest terms possible.

All sound is transmitted in waves described in terms of amplitude, wavelength, and frequency.

For noise-canceling headphones to achieve its purpose, three components make up their inner workings and they are all built into the ear cups.

• Microphone. It captures background noise that cannot be shut passively by the ear cups.
• Noise-canceling circuitry. It picks up the input from the mic and generates an opposing wave based on the incoming wave’s frequency and amplitude. At a point where these waves merge in antiphase (180 degrees opposing each other), the opposing wave negates the incoming wave, resulting in a new combined wave that’s free from ambient noise. This process is called destructive interference.
• Speaker. It absorbs the new noise-free wave generated through destructive interference and feeds it to your ears along with the normal sound.
• Battery. This entire process is made possible through a rechargeable battery, which basically explains why the word “active” is even there.

Here’s an illustration to further illuminate the process:

Noise-canceling headphones are best used in an environment where constant noise persists. Talk flights and train rides. They can cancel out aircraft engine’s noise by about 70%. On the downside, noise-canceling headphones are less effective in noises that change frequently in pitch as it’s more difficult for the headphones to respond in time.

Is It Worth Every Penny?

The best pairs of noise-canceling headphones come at a price and they perform well in distinguishing between a good and a bad sound. However, there have been complaints about compromised sound quality, particularly occasional hisses here and there, given the aforementioned process involved in eliminating background noise and retaining what a user wants to hear.

On a positive note, noise-canceling headphones help in taking the edge off fatigue brought by long-haul flights and road trips.