Science · 6 pages · 12 min
How noise-cancelling headphones make silence
The headset hears the rumble and adds the opposite pressure at your ear.
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From the opening
Noise-cancelling headphones make a local quiet by adding a sound that is the opposite of the unwanted one. Where the noise would have raised the pressure, the added wave lowers it, and the two changes cancel at the ear. The opening covers an inverted pressure at the ear, why low rumbles cancel better, and passive seal versus active wave.
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Inside
- An inverted pressure at the ear
- Why low rumbles cancel better
- Passive seal versus active wave
- What a sudden clap still does
- Where the idea stops applying
- A distinction worth keeping
Sources
- Destructive interference of opposite sound pressures
- Active noise control and its low-frequency advantage