There are three ways to cancel noise. Passive noise cancelling blocks sound physically, with cushioning and a tight seal. Active noise cancelling (ANC) goes further, using a microphone and a chip to build an inverse sound wave that cancels noise before it reaches your eardrums. Both of those only clean up what you hear. The third method, AI or software noise cancellation, works on the microphone signal itself, in real time, and removes background noise from your voice before it ever reaches whoever you’re talking to.
A century of trying to make the world quieter
Long before “ANC” was an acronym, people were stuffing wax in their ears, building padded flight helmets, wrapping headphones in foam and leather, just to make the world quieter for as long as they could stand wearing the new thing on or inside their ears. The full history of noise cancelling headphones runs from those wax earplugs through flight helmets to the first commercial ANC headset, but the idea never changed. It’s still the foundation of every pair sold today, and it still works, for what it was built for. Put a pair on during a flight or while you’re listening to music, and it does its job. But the moment you’re actually talking to someone, on a call, in a meeting, ANC is only solving half the problem.
Mic-side noise reduction wasn’t a new idea either, but it could only dampen a steady hum, an air conditioner, a low hiss. What it couldn’t do was tell the difference between your voice and a dog barking, or your voice and someone talking behind you, because it wasn’t listening for speech, it was just filtering out anything that looked like a constant, predictable pattern.
For a long time that didn’t matter much, because most calls came from somewhere quiet, a kitchen, a hallway, a desk in a study. The noise riding along with your voice only became a real problem once calls stopped happening from one fixed, quiet spot and started happening from wherever people actually are: a car with kids in the background, a co-working space, an airport. That’s the gap a real speech-recognizing model would eventually need to close.
What is passive noise cancellation?
Passive is the low-tech option, and it’s been around the longest. No electronics involved. It just physically blocks sound from reaching your eardrum. It’s the same idea as covering your ears with your hands, just built into foam and cushioning instead, freeing up your hands for more important things, like flying an airplane. It’s cheap, it needs no battery, and it works the second you put it on. Where it struggles is low frequencies. It’s decent at blocking higher-pitched sound, but a jet engine, an HVAC unit, road noise, all of that rumbles right through foam. That’s the gap active noise cancellation showed up to close.
What is active noise cancellation, and how does it work?
ANC stands for active noise cancellation. It adds a layer of electronics on top of passive isolation, and the physics behind it is genuinely clever. It’s called destructive interference, and here’s roughly what’s happening: Tiny microphones in the ear cup or earbud are constantly listening to the noise around you. A chip analyzes that sound wave in real time and builds an “anti-noise” wave, the exact inverse of what it just picked up. That anti-noise wave gets played back through the speaker alongside your music or call audio. When the original wave and the anti-noise wave meet, they cancel out, the peaks of one filling the troughs of the other, and the sound disappears before it hits your eardrum.
That’s why ANC handles steady, low-frequency noise so well, engine hum, cabin noise on a plane. It’s a predictable wave shape, easy to invert. What it’s bad at is anything sudden or irregular, a dog barking, a door slamming, someone talking, since there’s no stable pattern to build an inverse of fast enough.
That’s not the only limit, however. Above roughly 1–2 kHz, sound wavelengths get short enough that tiny errors in timing or microphone position can throw off the anti-noise wave entirely, adding to the noise instead of cancelling it. That’s why ANC stays confined to low frequencies no matter how fast the chip gets, the ceiling comes from the physics of the wave, not the electronics.
How do noise-cancelling headphones work?
Put those two together and you’ve got a pair of noise-canceling headphones. The seal blocks what it can, the electronics handle what gets through, and most of the time you never notice where one stops and the other starts.
What’s doing the work is the microphones, and where they sit changes a lot. A feedforward mic lives on the outside of the ear cup, so it hears noise before it reaches you, which makes it fast but leaves it guessing about what actually made it to your eardrum. A feedback mic sits inside, next to the driver, listening to roughly what you’re hearing, so it can correct its own mistakes, just a beat later. Most decent headphones now run both, which is why you’ll see “hybrid ANC” on the box.
Two settings worth knowing. Adaptive mode adjusts the cancellation as your surroundings change, so a train platform and a quiet office don’t get the same treatment. Transparency mode does the opposite, deliberately letting outside sound back in, for when you’d rather hear the barista than not.
What is AI noise cancellation, and how does it work?
Passive and ANC have one thing in common, no matter how different the engineering underneath: both only clean things up for the person wearing the headphones. Neither one touches the noise you’re sending out to someone else. That’s the actual gap AI noise cancellation fills, and it’s solving a different part of the problem entirely. Instead of working on sound coming into your ear, it works on sound leaving your microphone, before it’s transmitted anywhere.
A trained AI model listens to the raw mic signal, many times a second, and decides: is this a human voice, or is it something else? Keyboard clatter, a dog barking, someone talking in the background, wind, a construction crew outside, the AI model decides voice or not, and strips out the rest. This is really the whole idea behind Krisp’s AI noise cancellation: not making your world quieter, but making your voice clearer to whoever you’re talking to.
What that means in practice is the person on the other end hears you, not the room you happen to be sitting in. Doesn’t matter if you’re on a laptop, a phone, or a desk mic, no special hardware is needed. It’s also why this isn’t really a third flavor of the same two technologies, it’s its own category. Passive and ANC work on the input side, shaping what reaches your ear. AI noise cancellation works on the output side, shaping what leaves your mic. You can run all three at once, and they’re not competing with each other, they’re solving three different problems. If you want the technical side-by-side, ANC vs. AI-based noise cancellation goes deeper on the engineering behind each one.
Passive vs. active vs. AI noise cancellation
|
Passive |
Active (ANC) |
AI / software |
| What it does |
Physically blocks sound |
Electronically cancels sound waves |
Removes noise from your voice signal |
| Who benefits |
You, the wearer |
You, the wearer |
Whoever you’re talking to |
| How it works |
Foam, cushioning, a tight seal |
Microphone, chip, inverse sound wave |
AI model isolates voice from noise, in real time |
| Needs headphones? |
Yes |
Yes |
No, works with any mic |
| Best against |
Higher-frequency sound |
Steady, low-frequency sound (engine hum, HVAC) |
Any background noise on a call, barking, traffic, keyboards, crowds |
| Common products |
Foam earbuds, sealed ear cups |
Bose, Sony, AirPods Pro |
Krisp, built into meeting and calling apps |
Which type of noise cancelling do you actually need?
Worth asking yourself before assuming you need all three. Are you mostly trying to drown out a loud environment, a flight, a commute, an open office? That’s an ANC problem. Are you mostly on calls, and more worried about what the other person hears on their end? That’s not something headphones can fix at all, no matter how good they are, that’s a microphone problem, and it’s the one Krisp was built for.
A lot of people have the first kind covered and have never even thought about the second.
“ANC makes your world quieter. Krisp makes your voice clearer — in both directions.
Foam and chips can handle an airplane engine. But a barking dog, a siren, an espresso machine, and a toddler negotiating for snacks — leaking out of your mic or pouring in from everyone else’s? That’s not a headphone problem. That’s an AI problem.”
— Artavazd Minasyan, Co-founder at Krisp
On the software side, Krisp is one of the original names in this space. It’s been building AI noise cancellation since 2017, it’s used by teams at Sony, Cisco, Okta and Autodesk, and it’s often the benchmark other noise-cancellation tools compare themselves to. If AI noise cancellation is the fix for what headphones alone can’t handle, Krisp is the go-to choice for it.
FAQs
What is ANC?
ANC stands for active noise cancellation, the electronic process of using a microphone and chip to build an inverse sound wave that cancels ambient noise before it reaches your ear.
What does ANC mean on headphones?
On a pair of headphones, “ANC” just tells you whether the electronic noise-cancelling feature is built in, on top of whatever passive isolation the design already has.
What is ANC mode?
A setting on many headphones that turns active noise cancellation on or off, often paired with a “transparency” or “ambient sound” mode that does the opposite, letting outside sound in on purpose.
Does noise cancellation really work?
Yes, but how well depends entirely on what you’re trying to cancel. Against steady low-frequency noise, a plane cabin, a train, an air conditioner, good ANC is dramatic. Against a barking dog or a conversation two desks over, it barely moves the needle. Passive blocking is the reverse, better on higher-pitched sound and useless against rumble. That’s why the two are almost always sold together.
AI noise cancelling apps like
Krisp work differently, using AI to remove background noise from your audio in real time, making them especially effective for online meetings and calls.
What's the difference between noise cancelling and noise isolating?
Noise isolating is just another name for passive, the physical seal doing the work, no electronics and no battery. Noise cancelling usually means active, a mic and a chip building an inverse wave. Almost every pair of ANC headphones does both at once, so the distinction matters more on a spec sheet than it does on your head.
Do noise cancelling headphones work without music playing?
Yes. ANC runs independently of whatever you’re listening to, so you can switch it on with nothing playing and get the quiet on its own. That’s how most people use it for focus.
Can I still hear people talking with noise cancelling on?
Sharp, irregular sounds like speech are the hardest thing for ANC to cancel, so you’ll usually still hear voices, just quieter. A lot of headphones also include a transparency mode for exactly this reason.
AI noise cancellation on a call works the other way around, it’s built to keep the other person’s voice perfectly clear while stripping everything else out.
Is noise cancelling bad for your ears?
The technology itself isn’t the risk, your volume is. ANC’s anti-noise is just low-level sound, not pressure on the eardrum, and because you don’t have to crank the volume to hear over a noisy room, it can actually lower your total exposure.
Whether noise cancelling damages your hearing gets into what the research actually shows, and where it’s still an open question.
How do I block 100% of noise?
You can’t, not with anything on the market right now. Passive and ANC combined get close in controlled situations, like on a plane, but neither is a perfect seal, and ANC specifically struggles with anything sudden or irregular, like a voice or a sharp sound. That’s the hardware, not a fixable bug, so total silence isn’t really on the table.
If what you’re actually after is a quiet-sounding call rather than a quiet room, that’s a different question. No headphone technology fixes what the other person hears, since ANC only cleans up your side. That one’s solved by software noise cancellation instead.
Can software cancel noise without headphones?
Yes, that’s exactly what AI noise cancellation does. It works directly on your microphone’s signal, whether that’s a laptop, a phone, or a standalone desk mic — no special headphones or hardware required. AI noise cancelling software can work across
Windows,
macOS, and other desktop operating systems.
