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How headphone noise cancellation works

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Headphones can reduce distractions for the user by blocking incoming sound in one of two ways: passive and active. If you’ve ever wondered how they work, let us tell you the exciting story of…

How headphone noise cancellation works

Passive

Passive noise reduction works much as you’d expect: the headphones create a physical barrier that stops noise from reaching your ears.

Although headphones can’t block all incoming noises, the effectiveness increases as more of your ear is covered, and the design of the headphones improve.

Earbuds
Earbuds block the least amount of sound. However…
Blockage
Some earbuds come with plastic stoppers to reduce noise.
Heaphoo
Over-ear headphones block more sound. Some only go ON the ear, however.
Fully over-ear headphones have the greatest potential for passive noise cancellation.

Active

This is where things get interesting!

Higher-level headphones come equipped with active noise cancellation: they literally use sound to block other incoming noises, thus creating a clearn listening environment around your ears.

That’s pretty cool!

But how does blocking sound with sound work? To put it simply: sound travels in waves, which are picked up by receptors in the human ear. When two sound waves that are in perfect opposition (180 degrees out of phase) collide, they cancel each other out. Imagine ocean waves smashing each other, reduced to utter nothingness!

Better yet, watch this awesome science video for a clear example:

So, how do headphones ensure their noise canceling waves are 180 degrees out of phase with incoming distractions? Many advanced headphones pick up sound with a built-in microphone and quickly adjust to cancel it out.

As an unfortunate side effect, the crashing sound waves can develop “cabin pressure,” and uncomfortable sensation of force on the eardrums. Luckily, better headphone designs reduce the sensation drastically.

For example, Bose QC35’s send their noise cancellation through the ear cushions to keep the cabin pressure away from the inner cup:

Earcups

The end result? Better listening, less distracting noises, and more awesome music!

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