How do noise-cancelling headphones work?
Microphones pick up the noise around you, a chip creates a mirror-image sound wave, and the speaker plays it so the two waves cancel each other out.
The headphones listen to the world
Tiny microphones on the outside pick up the noise around you, thousands of times every second.
Share this stepA mirror-image wave is calculated
A small chip creates the exact opposite wave. Where the noise goes up, the new wave goes down.
The waves cancel each other out
The speaker plays the anti-noise at the same moment the noise reaches your ear. Up plus down adds up to almost nothing.
Silence, almost.
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It works best on steady, low sounds like engine rumble and fans. Sudden sounds and voices partly slip through.
Common follow-up questions
Does it block out voices?
Partly. Steady, low sounds are removed best. Voices and sudden noises change too quickly to be cancelled completely.
Why does it feel like pressure in my ears?
The low rumble disappears, and your brain reads the silence a bit like riding in an elevator. It is harmless and usually fades as you get used to it.
Is it good for your hearing?
Usually, yes. With less background noise you don’t need to turn the volume up as much.
What is transparency mode?
The same microphones work the other way around: they deliberately let outside sound in so you can hear your surroundings.
