How Noise Cancelling Works — and What It Cannot Do
Why ANC kills engine rumble but not a crying baby, what our decibel numbers mean, and how to get the most from any pair.
Active noise cancelling uses microphones to sample outside sound and plays an inverted copy through the drivers so the two cancel. It works best on steady, low-frequency noise — engines, air conditioning, road roar — because those sounds are predictable.
What our numbers mean
We play recorded aircraft cabin noise and measure how much reaches an ear simulator with ANC on. The Bose QC Ultra removed 32 dB and the Sony XM6 31 dB; the Anker Space One 22 dB. Each 10 dB is roughly a halving of perceived loudness, so the flagships make a cabin sound about a quarter as loud as the budget pair does.
What it cannot do
Voices, babies, keyboards and sudden sounds are irregular and higher-pitched; ANC reduces them a little and the earcup seal does the rest. Nothing in the ranking makes an open office silent.
Getting the most from any pair
- Fit matters more than the model: glasses arms break the seal.
- Run the app's optimiser (Sony) or ear-tip/fit test where offered.
- Turn off adaptive modes on planes; they hunt.
» See the full rankings: Best Noise-Cancelling Headphones of 2026, Best Headphones for Travel and Flights .