Technology
How do noise-cancelling headphones work?
Noise-cancelling headphones work by listening to outside noise with tiny microphones, then generating a sound wave that is its exact opposite. When the two waves meet, they cancel out, leaving you with much quieter surroundings.
See it in motion.
Watch a 2-minute animated lesson that shows exactly how noise-cancelling headphones works.
Step by step
- 1Built-in microphones pick up the surrounding noise.
- 2A chip instantly creates an 'anti-noise' wave — the mirror image of that sound.
- 3When the original and opposite waves overlap, they cancel (destructive interference).
- 4It works best on steady, low rumbles like engines and air conditioning.
- 5Sudden, high-pitched sounds are harder to cancel than constant drones.
Frequently asked questions
- How do noise-cancelling headphones cancel sound?
- They play a wave that's the exact opposite of the incoming noise; the two cancel each other out, a trick called destructive interference.
- Why can't they cancel all sounds?
- Sudden or high-frequency sounds change too fast to mirror in time, so steady low rumbles cancel best while sharp noises leak through.
- Do noise-cancelling headphones need power?
- Yes — the microphones and processing chip need a battery, which is why active noise cancellation stops when the battery dies.