Noise cancellation, usually called active noise cancellation (ANC), uses microphones to listen to ambient sound and the headphone speaker to play an inverted copy of that waveform. When the original and inverted waves meet, they partly cancel out.
Why it matters
ANC works best on steady, low-frequency noise such as aircraft engines, train rumble, and air conditioning. It is less effective on sudden or high-pitched sounds like speech, which is why passive isolation from a good seal still matters. ANC needs a battery and processing, so it can add a small amount of hiss and affect battery life. Many headphones also offer a transparency or ambient mode that passes outside sound through.
The same idea is used in calls: microphone noise suppression removes background sound from your voice, often with machine learning, and is a separate feature from headphone ANC.
Example
Feedforward ANC uses a microphone on the outside of the earcup, feedback ANC uses one inside near the ear, and hybrid systems use both. A hybrid pair on a flight can noticeably reduce engine drone, while the cabin announcement is still audible.
Common mistakes
- Expecting silence. ANC reduces noise; it does not remove it.
- Wearing earbuds with the wrong tip size, which breaks the seal.
- Mixing up ANC with call noise suppression.
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