Active Noise Cancellation (ANC)
Active noise cancellation uses microphones and a speaker to produce sound that cancels steady background noise before it reaches your ears.
On this page 3 sections
How it works
Small microphones on the outside of an earphone or headphone listen to the noise around you. A chip then creates a sound wave that is the exact opposite of that noise and plays it through the speaker. When the two waves meet, they largely cancel each other, so you hear less of the hum.
Types you will see
- Feedforward: microphones sit outside the ear and catch noise early.
- Feedback: a microphone sits inside the ear cup and checks what actually reaches you.
- Hybrid: uses both together for a stronger effect.
Many models also have a transparency mode. It does the reverse and passes outside sound in through the microphones, so you can hear announcements or traffic.
What it does not promise
ANC works best on steady, low sounds such as engine drone, fans and air-conditioner hum. It handles sudden or high sounds, such as speech or a horn, far less well. It does not block all sound, because the ear tip or ear cup also isolates noise physically. Running ANC uses battery power, so playback time is usually shorter with it on. A decibel figure quoted for ANC depends on the test method and does not show how quiet it will feel in daily life.