--- title: How Noise-Cancelling Headphones Actually Remove Sound in... description: Noise-cancelling headphones use microphones, digital signal processing and speakers to generate 'anti-noise' that destructively interferes with incoming sound... canonical: https://daily.dev/posts/how-noise-cancelling-headphones-actually-remove-sound-in-real-time-baukw2zwd twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: How Noise-Cancelling Headphones Actually Remove Sound in Real Time | daily.dev og:description: Noise-cancelling headphones use microphones, digital signal processing and speakers to generate 'anti-noise' that destructively interferes with incoming sound... og:url: https://daily.dev/posts/how-noise-cancelling-headphones-actually-remove-sound-in-real-time-baukw2zwd og:image: https://api.daily.dev/og/posts/BAukw2zwd.png og:image:alt: How Noise-Cancelling Headphones Actually Remove Sound in Real Time og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # How Noise-Cancelling Headphones Actually Remove Sound in Real Time **[freeCodeCamp](https://daily.dev/sources/freecodecamp)** · 11 min read · 20 upvotes · 1 comments ## Summary Noise-cancelling headphones use microphones, digital signal processing and speakers to generate 'anti-noise' that destructively interferes with incoming sound near your ear. The adaptive FxLMS algorithm is one of the most established, continuously tweaking filter coefficients using a measured 'error' signal. Three architectures exist: feedforward (external mic), feedback (internal mic), and hybrid, each trading prediction for correction. Low-frequency steady sounds like engine rumble cancel well, but high-frequency or sudden sounds like claps or speech are far harder to track in real time. A 2012 study found ANC users chose listening volumes up to 4 dB lower than with ordinary earbuds. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### What algorithm do noise-cancelling headphones use to generate anti-noise in real time? Many high-end noise-cancelling headphones use the Filtered-x Least Mean Squares (FxLMS) algorithm, one of the most established methods in active noise control. The controller produces a cancellation signal, an internal microphone measures the residual 'error' noise, and the algorithm uses that error along with a digital model of the speaker-to-ear acoustic path to continuously adjust its filter coefficients. _Engineers building real-time audio DSP can find adaptive filtering deep dives like this on daily.dev._ ### Why do noise-cancelling headphones block engine noise but not a crying baby or conversation? Low-frequency sounds like engine rumble or ventilation noise have long wavelengths and change slowly, giving the controller time to estimate the waveform and generate an accurate cancellation signal. High-frequency or sudden sounds, like a slamming door, hand clap, or speech, change faster than the processing loop can track, making them far harder to cancel effectively. _Anyone evaluating ANC hardware trade-offs can track these acoustic engineering explainers on daily.dev._ ### What is the difference between feedforward, feedback, and hybrid active noise cancellation? Feedforward ANC places a microphone outside the ear cup to listen to noise before it reaches the ear, giving a head start but requiring precise delay estimation. Feedback ANC uses an internal microphone to measure residual noise inside the cup and correct output, but has less ability to anticipate sudden sounds. Hybrid systems combine both external and internal microphone data for prediction plus correction. _Developers comparing ANC hardware architectures can keep up with acoustic engineering breakdowns on daily.dev._ ## Community discussion Top comments from developers on daily.dev. **@hardik15** · 1 upvotes > Good to see this from FreeCodeCamp. I was only seeing about programming, Infra and stack only on FCC. This combination of SW/HW is a good expansion. ## Similar posts on daily.dev - [I Built Adaptive Noise Cancellation in MATLAB Then Realized It Was Online Regression](https://daily.dev/posts/i-built-adaptive-noise-cancellation-in-matlab-then-realized-it-was-online-regression-xzqzhhdpa) · Medium · 0 upvotes · 0 comments - [Apple unveils AirPods 5 with improved active noise cancellation](https://daily.dev/posts/apple-unveils-airpods-5-with-improved-active-noise-cancellation-7mbkh6cmq) · TechCrunch · 0 upvotes · 0 comments - [Less Is More: Why Audio on SoundCloud Looks Different](https://daily.dev/posts/less-is-more-why-audio-on-soundcloud-looks-different-hr2cz3zhl) · Backstage Blog · 0 upvotes · 0 comments --- Tags: [#algorithms](https://daily.dev/tags/algorithms), [#embedded](https://daily.dev/tags/embedded) [View this post on daily.dev](https://daily.dev/posts/how-noise-cancelling-headphones-actually-remove-sound-in-real-time-baukw2zwd) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"How Noise-Cancelling Headphones Actually Remove Sound in Real Time","url":"https://daily.dev/posts/how-noise-cancelling-headphones-actually-remove-sound-in-real-time-baukw2zwd","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/how-noise-cancelling-headphones-actually-remove-sound-in-real-time-baukw2zwd"},"datePublished":"2026-10-26T16:35:34.677Z","dateModified":"2026-10-26T16:36:06.638Z","description":"Noise-cancelling headphones use microphones, digital signal processing and speakers to generate 'anti-noise' that destructively interferes with incoming sound...","image":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/ad94b78d3db36ca8d6d1e9d26c3afddb?_a=AQAEuop","thumbnailUrl":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/ad94b78d3db36ca8d6d1e9d26c3afddb?_a=AQAEuop","isAccessibleForFree":true,"articleSection":"freeCodeCamp","inLanguage":"en","publisher":{"@type":"Organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180}},"author":{"@type":"Organization","name":"freeCodeCamp","logo":"https://media.daily.dev/image/upload/t_logo,f_auto/v1628412854/logos/freecodecamp","url":"https://daily.dev/sources/freecodecamp"},"commentCount":1,"discussionUrl":"https://daily.dev/posts/how-noise-cancelling-headphones-actually-remove-sound-in-real-time-baukw2zwd","interactionStatistic":[{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":20},{"@type":"InteractionCounter","interactionType":{"@type":"CommentAction"},"userInteractionCount":1}],"keywords":"algorithms,embedded","timeRequired":"PT11M"} {"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https://daily.dev"},{"@type":"ListItem","position":2,"name":"freeCodeCamp","item":"https://daily.dev/sources/freecodecamp"},{"@type":"ListItem","position":3,"name":"How Noise-Cancelling Headphones Actually Remove Sound in Real Time"}]} {"@context":"https://schema.org","@type":"WebPage","@id":"https://daily.dev/posts/how-noise-cancelling-headphones-actually-remove-sound-in-real-time-baukw2zwd","comment":[{"@type":"Comment","text":"Good to see this from FreeCodeCamp. I was only seeing about programming, Infra and stack only on FCC. This combination of SW/HW is a good expansion.","datePublished":"2026-10-28T06:27:44.658Z","url":"https://daily.dev/posts/BAukw2zwd#c-Qcun9k7tR","author":{"@type":"Person","name":"Hardik","url":"https://daily.dev/hardik15","image":"https://media.daily.dev/image/upload/s--O0TOmw4y--/f_auto/v1715772965/public/noProfile"},"interactionStatistic":{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":1}}]} {"@context":"https://schema.org","@type":"FAQPage","@id":"https://daily.dev/posts/how-noise-cancelling-headphones-actually-remove-sound-in-real-time-baukw2zwd#faq","mainEntity":[{"@type":"Question","name":"What algorithm do noise-cancelling headphones use to generate anti-noise in real time?","acceptedAnswer":{"@type":"Answer","text":"Many high-end noise-cancelling headphones use the Filtered-x Least Mean Squares (FxLMS) algorithm, one of the most established methods in active noise control. 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