How does noise cancelling work?
Short answer
Active noise cancelling (ANC) uses microphones to pick up outside noise and plays an inverted sound wave that cancels it. It works best against steady low sounds like engines and air conditioning, and less well against voices and sudden sounds.
Active and passive
Passive isolation comes from the fit: ear tips or ear cushions physically block sound, especially high tones. Active cancelling works electronically against low, steady noise. Good headphones combine both.
What it blocks well
- Aircraft and train engines
- Road noise on buses
- Air conditioning and fans
- Office hum
What to look for
The fit matters as much as the technology: earbuds need the right tip size. Many models have a transparency mode that lets voices through when you need them, and adaptive modes that adjust to your surroundings.
Questions and answers
Is noise cancelling bad for your ears?
No. ANC does not harm hearing; it can even help, because you need less volume in noisy places. Some people feel a slight pressure at first.
Over-ear or earbuds for noise cancelling?
Top over-ear headphones still block a bit more, especially high frequencies, but the best earbuds come close and are easier to carry.