Feedforward, feedback and hybrid mics, why ANC loves a droning engine, and how much quiet you can really expect.
Updated September 19, 2026
Active noise cancelling (ANC) is the feature people notice most on a plane or a busy commute — and one of the most misunderstood. It doesn't create silence; it uses microphones and inverse sound waves to cancel noise before it reaches your ear. Understanding how it works tells you what to expect and what to look for.
ANC relies on microphones that listen to noise so the headphones can play an opposite "anti-noise" wave. Feedforward systems put the mic on the outside of the earcup, catching noise before it reaches you. Feedback systems place the mic inside, near your ear, measuring what actually gets through. Hybrid ANC — now common on good headphones — combines both, and it's generally the most effective and consistent approach.
ANC is best at constant, low-frequency sound — the drone of a jet engine, air conditioning, road rumble. Those steady waves are predictable, so the system can generate an accurate opposite. Sudden, high-frequency sounds like a voice or a clatter are much harder to cancel, which is why ANC hushes a plane's roar but doesn't mute the person talking next to you. That's also where a good passive seal and physical isolation pick up the slack.
Numbers help set expectations: a solid ANC system commonly delivers between 20 and 40 dB of reduction, which cuts the background noise you perceive to roughly a quarter or less of its original level. That's a dramatic drop in droning noise, but not total silence — and it varies a lot by fit. On earbuds especially, a tip that doesn't seal leaks bass and lets noise in, so trying the included tip sizes matters as much as the ANC circuitry.
When comparing headphones, weigh independent measurements of low-frequency attenuation over marketing claims, and remember that a good transparency mode — to let noise back in when you need it — is part of the same feature set.
This article is original analysis grounded in independently verified references, including non-English outlets. The facts above are sourced so you can check them yourself.