--- title: How noise cancelling headphones work description: A microphone hears the noise, the headphone plays its opposite, and the two cancel. Why that works on engine drone below 1 kHz but not on nearby voices. source: https://oohunt.com/blog/how-noise-cancelling-headphones-work published: 2026-10-25 modified: 2026-10-25 author: Oohunt Deal Desk site: Oohunt disclosure: Product links are Amazon affiliate links. testing: None. This guide makes no hands-on testing claim. Factual claims are attributed to named manufacturer sources and linked inline. --- # How noise cancelling headphones work [Oohunt Deal Desk](https://oohunt.com/how-we-choose-deals) · Buying guides · October 25, 2026 · 7 min read As an Amazon Associate we earn from qualifying purchases made through links on this page. **A microphone listens to the noise around you, and the headphone plays that same sound back with the wave turned upside down.** Where a pressure peak was heading for your eardrum, the headphone sends a trough. They meet, and mostly cancel. The [published description](https://pmc.ncbi.nlm.nih.gov/articles/PMC9572409/) is that the circuit generates anti-noise with a magnitude equal to and a phase opposite to the ambient noise, producing destructive interference. That is the entire idea, and it has one consequence that explains almost every complaint people have about these headphones. ## It only works properly on low sounds The same source puts it plainly: current ANC technology achieves good cancellation for noise **below about 1 kHz**. That boundary sorts the world into two piles. - **Cancelled well:** aircraft cabin drone, road and tyre rumble, train noise, air conditioning, fan and server hum, the low half of traffic. All steady, all low. - **Barely touched:** speech, especially the consonants that carry meaning. Keyboards. Cutlery. A door slamming. A dog. Children. So the person who buys ANC for a flight is delighted, and the person who buys it for an open-plan office is disappointed, and both got exactly what the physics allows. If voices are your problem, what you want is a seal rather than a circuit, which is the subject of [noise cancelling versus noise isolating](https://oohunt.com/blog/noise-cancelling-vs-noise-isolating). There is a reason for the limit. Cancelling a wave means producing its opposite at the right instant, and the shorter the wave, the less margin there is. High frequencies arrive and leave too quickly for the correction to land in the right place, every time, at the particular point in space where your eardrum happens to be. ## Where the microphones sit Three arrangements exist, and the box usually names one. The [patent description](https://patents.google.com/patent/US11678116B1/en) is specific: feedforward microphones are situated externally on the headphone, feedback microphones are placed inside close to the speaker drivers, and the two can be combined into a hybrid with better overall performance than either alone. How much better is not stated, which is worth remembering when a listing makes hybrid sound like a tier rather than a layout. ## The seal is doing half the work This is the part the marketing skips, because you cannot sell it as a feature. Before any electronics run, the physical object is already blocking sound: a cushion against your skull, or a tip wedged in your ear canal. That blocking handles the high frequencies the circuit cannot. Which is why [Apple’s own guidance](https://support.apple.com/en-us/119849) on ear tips says a good seal with your ear canal gives you better noise cancellation and richer bass, and why its earbuds ship with a test for it. A gap at the seal does not just leak high frequencies in; it undermines the cancellation too. Practically: - **In-ear:** try every tip size in the box. The one that came fitted is a guess about an average ear, and you may need different sizes left and right. - **Over-ear:** the cushion has to meet skin all the way round. Glasses arms are the usual leak. - **If it got worse:** Apple notes that losing bass or hearing more background with ANC on can mean the earbuds need cleaning. Blocked mesh and compressed tips both show up as weaker cancellation. ## Why nobody can tell you how many decibels Industrial hearing protectors are tested to a standard and carry a published rating. Consumer headphones are not and do not. So when one box says it removes 95% of noise and another claims twice the cancellation of the previous model, those are each measured in-house, at frequencies of the manufacturer’s choosing, against a baseline of their choosing. They are not comparable with each other, and there is no governing figure to convert them into. We are not going to print a decibel number for the same reason. No source we could read supports one. What you can rely on is the shape of the thing: strong on steady low noise, weak on sudden high noise, and dependent on the seal. ## What this means when buying - **Flying or commuting?** ANC is the right purchase, and even inexpensive hybrid models handle cabin drone well. This is the job it was invented for. - **Open-plan office, or a talkative household?** Prioritize the seal, and expect to cover the remaining speech with sound rather than silence. - **Ignore the percentages.** They are not a shared scale. - **Try the fit before judging the headphones.** More complaints come from a bad seal than from bad electronics. ## Headphones worth a look Prices change often, so check the current one on Amazon. What we would buy (4) Affiliate links - [Soundcore Anker Q20i hybrid active noise cancelling headphones](https://oohunt.com/out/B0C3HCD34R?p=blog-how-anc-works): Says hybrid on the box, meaning microphones inside and out, at the cheap end of the range. - [Sony WH-CH720N wireless noise cancelling over-ear headphones](https://oohunt.com/out/B0BS74M665?p=blog-how-anc-works): Over-ear, so the cushion does the high-frequency work while the electronics handle the drone. - [Bose QuietComfort Bluetooth headphones with active noise cancelling](https://oohunt.com/out/B0CCZ1SQ8G?p=blog-how-anc-works): The line that made ANC a consumer product, and still the default comparison. - [Apple AirPods Pro 3 wireless earbuds with active noise cancellation](https://oohunt.com/out/B0FQFB8FMG?p=blog-how-anc-works): In-ear, where the tip seal matters most. These have a built-in test for whether yours is sealing. No prices or star ratings here. Prices change daily and we do not track them, so Amazon shows you the current one. Nothing on this list has been tested. ## Common questions ### How do noise cancelling headphones work? A microphone samples the sound around you, and the headphone plays a copy of it with the waveform flipped upside down. Equal size, opposite phase. The two waves meet at your ear and cancel, which acousticians call destructive interference. ### Why don't noise cancelling headphones block voices? Because speech sits mostly above the band ANC is good at. Published work puts good cancellation below about 1 kHz, which covers engine drone and fan hum. The consonants that make speech intelligible run well above that, so they get through. ### What is the difference between feedforward and feedback ANC? Where the microphone is. A feedforward system puts microphones on the outside of the headphone to hear noise before it arrives. A feedback system puts them inside, next to the driver, to hear what actually reached your ear. Hybrid uses both. ### Is hybrid ANC better? That is the engineering claim. The patent literature describes combining feedforward and feedback into a hybrid system with superior overall performance to either used on its own. It says nothing about how much better, and neither will we. ### How many decibels do noise cancelling headphones block? There is no answer you can trust across brands. Unlike industrial hearing protectors, consumer headphones carry no standardized noise reduction rating, so the percentages on the box are each measured the maker's own way and cannot be compared. ### Why does noise cancellation get worse over time? Usually the seal rather than the electronics. Apple notes that a loss of bass or more background sound with ANC on can mean the earbuds need cleaning, and worn or wrong-sized ear tips do the same thing. --- The companion to this one is [noise cancelling vs noise isolating](https://oohunt.com/blog/noise-cancelling-vs-noise-isolating), which covers what a seal does that a circuit cannot. More in [electronics](https://oohunt.com/category/electronics). --- ## More guides - [Frigidaire refrigerator water filter: which one fits](https://oohunt.com/blog/frigidaire-refrigerator-water-filter) - [Power banks for laptops: what actually works](https://oohunt.com/blog/power-bank-for-laptop) - [Can you put foil in an air fryer?](https://oohunt.com/blog/foil-in-air-fryer)