Last updated: October 2026
Noise cancelling can feel like magic: you flip a switch and a plane engine nearly disappears. In reality it’s clever physics plus fast processing. Understanding how it works also explains why ANC headphones are brilliant on flights but less impressive in a chatty office.
How Does Active Noise Cancelling Work?
Sound travels as pressure waves. ANC headphones use microphones to sample the noise around you thousands of times a second. A processor creates a mirror-image wave with peaks where the noise has troughs, and the headphone driver plays it. When the two waves meet at your ear, they largely cancel out.
This happens continuously and almost instantly, which is why you hear a sudden drop in background hum the moment you switch ANC on.
What Are Feed-Forward, Feedback and Hybrid ANC?
Feed-forward ANC uses microphones on the outside of the ear cup to hear noise before it reaches you. Feedback ANC uses microphones inside the ear cup to measure what actually reaches your ear. Hybrid ANC uses both, which is why it’s more effective across a wider range of sounds.
| Type | Mic position | Strength |
|---|---|---|
| Feed-forward | Outside the ear cup | Good on mid frequencies |
| Feedback | Inside the ear cup | Good on low frequencies, self-correcting |
| Hybrid | Both | Best overall coverage |
Many budget headphones now use hybrid ANC, including the Soundcore Q20i with two internal and two external mics, featured in our guide to the best noise cancelling headphones under $100.
What Kind of Noise Does ANC Cancel Best?
ANC is most effective on steady, low-frequency sounds: aircraft and train engines, traffic rumble, fans and air conditioning. It’s less effective on sudden or high-pitched sounds like voices, clattering dishes or a baby crying, because they change too quickly and their short wavelengths are harder to predict and cancel.
Where Does Passive Noise Isolation Fit In?
Passive isolation is the physical blocking of sound by well-sealed ear cushions or ear tips. It handles high-frequency sounds that ANC struggles with. The best results come from combining both: good padding blocks the highs, and ANC removes the lows.
That’s why a good seal matters even on ANC headphones. Glasses arms or a loose fit can let noise leak in and make ANC seem weaker.
What Is Adaptive Noise Cancelling?
Adaptive ANC automatically adjusts the strength of noise cancelling to your environment and how the headphones fit. On a quiet street it may ease off; on a plane it ramps up. Some adaptive systems also compensate for sound leaking around glasses or hair.
The Soundcore Space One and JBL Tune 770NC both use adaptive ANC, a feature that used to be limited to premium headphones.
Frequently Asked Questions
Does noise cancelling block all sound?
No. ANC significantly reduces steady, low-frequency noise but can’t eliminate everything. Voices, sudden sounds and high-pitched noises still come through, though passive isolation from the ear cushions helps reduce them.
Is active noise cancelling the same as noise isolation?
No. Noise isolation is physical blocking by cushions or ear tips. Active noise cancelling uses microphones and anti-noise sound waves. Most ANC headphones use both together for the best result.
Why does ANC work better on planes than in offices?
Plane engines produce steady, low-frequency noise, which ANC handles best. Offices are full of voices and sudden sounds, which change too quickly to cancel completely.
Does noise cancelling drain the battery?
Yes, a little. ANC needs the microphones and processor running constantly. That’s why headphones list separate battery figures with ANC on and off, with the ANC-on number usually lower.
Can I use noise cancelling without music?
Yes. Many people wear ANC headphones with nothing playing to reduce noise while studying, working or sleeping on flights. The noise cancelling works independently of audio playback.
The Bottom Line
Active noise cancelling measures noise with microphones and cancels it with an opposite sound wave. It shines on engines and hums, while good cushions handle higher sounds. For affordable headphones that use hybrid and adaptive ANC, see our best noise cancelling headphones under $100.