How ANC works
ANC explained: how active noise cancelling works, how it differs from passive isolation, what affects quality, and how flagship and mid-price headphones compare.
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At a glance
Active noise cancelling (ANC) uses microphones on the headphone to measure the noise around you, then plays an inverted anti-noise signal through the drivers that cancels it before it reaches your ear. It works best on low, steady sound such as aeroplane engines, train rumble and air conditioning, and least on sudden, high-pitched sound such as voices. ANC quality varies far more than marketing implies: the Sony WH-1000XM6 leads the catalogue, while the Sennheiser ACCENTUM Plus shows how much of that benefit a mid-price pair now delivers.
What active noise cancelling is
Active noise cancelling is electronic noise reduction. Tiny microphones sample the surrounding sound thousands of times a second, a processor calculates the exact opposite waveform, and the drivers play that anti-noise alongside your music. Where the noise and the anti-noise meet, they cancel, so you hear less of the world. It is different from passive isolation, which is just the physical seal of the earcup blocking sound.
How ANC works: feedforward and feedback mics
Good ANC uses two sets of microphones. Feedforward mics sit on the outside of the earcup and hear noise before it reaches you, giving the processor a head start. Feedback mics sit inside the cup, near your ear, and measure what actually got through so the system can correct itself. Headphones that combine both, called hybrid ANC, cancel a wider range of frequencies than either alone. The strength of the processor and the quality of the mic placement are why a flagship cancels so much more than a budget pair, even when both claim ANC.
ANC vs passive isolation
Passive isolation is the noise an earcup or ear tip blocks just by sealing your ear, with no electronics. It handles high frequencies well, voices, clatter and hiss, because short sound waves are easy to physically block. ANC handles the opposite end: long, low-frequency waves such as engine drone that pass straight through a seal. The best headphones combine both, a good seal for highs and strong ANC for lows, which is why fit matters even on an ANC pair.
Transparency mode is the other half
Transparency, or ambient, mode uses the same microphones in reverse: instead of cancelling the outside world, it pipes it through so you can hear a conversation or a train announcement without removing the headphones. The quality of transparency varies as much as ANC. The best, on the Sony WH-1000XM6 and Bose, sound natural; weaker versions sound hollow or hissy. If you will use headphones in shops, offices or on foot, judge transparency as carefully as cancellation.
What actually affects ANC quality
- Processor and tuning: the single biggest factor, and the reason flagships lead. It is not on a spec sheet, so it shows up in reviews, not numbers.
- Hybrid mics: feedforward plus feedback mics cancel a wider band than a single-mic budget design.
- Fit and seal: a poor seal lets high-frequency noise leak in that ANC cannot catch. Over-ears seal more consistently than earbuds.
- Adaptive ANC: the best headphones adjust cancellation to your surroundings and even to wind, rather than running one fixed level.
Flagship ANC: Sony WH-1000XM6
Sony WH-1000XM6 specifications
- Noise cancelling: Yes
- Battery life: 30 h
- Driver size: 30 mm
- LDAC hi-res: Yes
- Weight: 250 g
The Sony WH-1000XM6 shows what the best ANC does. Hybrid microphones and a dedicated processor cancel a wide band of noise deeply, and adaptive modes read your surroundings to adjust on the move. Its transparency mode is among the most natural available. This is the level of cancellation that makes a long-haul flight or an open-plan office genuinely quiet, and it is why the WH-1000XM6 tops our best wireless headphones ranking.
Sony WH-1000XM6 - pros and cons
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Mid-price ANC: Sennheiser ACCENTUM Plus
Sennheiser ACCENTUM Plus specifications
- Noise cancelling: Yes
- Battery life: 50 h
- Driver size: 37 mm
- Weight: 227 g
The Sennheiser ACCENTUM Plus shows how far mid-price ANC has come. It does not cancel quite as deeply or adapt as cleverly as the Sony, and its transparency mode is a step behind, but for everyday commuting and office use most of the benefit is there. The gap is now smaller than the price difference suggests, which is why ANC is no longer a flagship-only feature. For buyers who want strong cancellation without paying the most, mid-price ANC like this is the value sweet spot.
Sennheiser ACCENTUM Plus - pros and cons
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Radar · 0-100 scores
- Sony WH-1000XM6
- Sennheiser ACCENTUM Plus
ANC vs passive isolation at a glance
| Trait | Active (ANC) | Passive isolation |
|---|---|---|
| What it is | Electronic anti-noise | Physical earcup seal |
| Best on | Low, steady noise (engines) | High noise (voices, clatter) |
| Needs power | Yes, uses battery | No |
| Needs good fit | Helps | Essential |
| Varies by model | Hugely (processor) | By earcup and pads |
How much ANC do you actually need
Buy flagship ANC if you commute or fly often
If you spend hours on planes, trains or in a noisy open-plan office, the deepest cancellation is worth paying for, and the Sony WH-1000XM6 leads. The difference between flagship and mid-price ANC is most obvious exactly in those environments.
Mid-price ANC is enough for most people
For occasional commutes and home use, mid-price ANC such as the Sennheiser ACCENTUM Plus delivers most of the benefit for less. Spend the saving on sound quality or battery instead. See the full ranking in Best wireless headphones UK 2026 and the in-ear options in Best wireless earbuds UK 2026.
Verdict
Active noise cancelling uses microphones and anti-noise to cancel low, steady sound; passive isolation blocks high sound with a seal; the best headphones combine both. ANC quality is driven by the processor and mic design, not a spec on a box, so it varies hugely between models. The Sony WH-1000XM6 shows the flagship ceiling, and the Sennheiser ACCENTUM Plus shows how much of that benefit a mid-price pair now delivers.
Frequently asked questions
What is active noise cancelling?
Active noise cancelling uses microphones on the headphone to measure surrounding sound, then plays an inverted anti-noise signal through the drivers that cancels it before it reaches your ear. It works best on low, steady noise such as engines and least on sudden, high-pitched sound such as voices.
How does noise cancelling work?
Microphones sample the surrounding sound thousands of times a second, a processor calculates the opposite waveform, and the drivers play that anti-noise alongside your music. Where the noise and anti-noise meet they cancel. Hybrid systems use outer feedforward and inner feedback microphones to cancel a wider range.
What is the difference between ANC and passive isolation?
Passive isolation is the noise an earcup blocks just by sealing your ear, which handles high frequencies well. ANC uses electronics to cancel low frequencies such as engine drone that pass through a seal. The best headphones combine both, which is why fit still matters on an ANC pair.
Does noise cancelling affect sound quality?
On good headphones the effect is minimal; flagships such as the Sony WH-1000XM6 tune ANC so it barely changes the music. On weaker headphones, aggressive ANC can add a faint pressure sensation or thin the bass. You can usually lower or turn off ANC when you do not need it.
Is expensive noise cancelling worth it?
For frequent flyers and commuters, yes: the deepest cancellation is most obvious in noisy environments. For occasional use at home, mid-price ANC such as the Sennheiser ACCENTUM Plus delivers most of the benefit for less, since the gap is now smaller than the price difference suggests.
Updated · Sam Reid · More over-ear headphones