How Do Noise Cancelling Headphones Work

Noise cancelling headphones have become increasingly popular in recent years. Their ability to block out external noise makes them ideal for listening to music or podcasts on a noisy commute or getting work done in a busy office.

But how exactly do noise cancelling headphones work their magic?

Active noise cancelling headphones use the built-in microphones and sound processing technology to actively generate sound waves that cancel out incoming noise. However, passive noise cancelling headphones uses physical barrier and design of the headphones, which helps block out external sounds.

Let’s take a closer look at the technology behind these clever devices that can silence the world around you.

What is Noise Cancellation

Noise cancellation, also known as active noise control (ANC), is a technology that reduces unwanted background sound by generating a soundwave that actively cancels it out. This is achieved by using built-in microphones to pick up low frequency ambient noise, generating an inverse sound wave to that noise, and playing it simultaneously through the headphones speakers.

The original sound wave and the inverted wave cancel each other out through destructive interference, resulting in silence or greatly reduced background noise.

This differs from passive noise isolation used in some headphones and earplugs, which rely solely on physical barriers like foam cushioning to muffle sound.

Types of Noise Cancellation for Different Needs

Noise cancelling headphones actually utilize various types and settings to suit different environments and user preferences:

  • Active Noise Cancellation: Uses microphone input and speaker output to analyze and cancel exterior noise in real-time. Long used in over-ear models, the tech now fits into earbuds too.
  • Passive Noise Cancellation: Relies on physical barriers like snug ear cup and earbud designs to passively block noise without powered electronics.
  • Adaptive ANC: Automatically adjusts active cancellation levels based on the ambient noise environment.
  • Adjustable ANC: Allows manual control over the amount of active noise cancellation applied.
  • Transparency Mode: Enables desired ambient sounds to pass through clearly on demand.

Active noise cancellation allows more dramatic sound reduction across a broader range of frequencies. It requires power and electronics to generate the anti-noise soundwave, so noise cancelling headphones are battery powered rather than fully passive.

Overall noise cancellation is typically limited to around 20 decibels of attenuation.

However, according to a study published in Hearing Review, the average amount of noise reduction provided by noise cancelling headphones in 85 dBA of white noise is significant, around 15-20 dB. Though the amount of reduction varies based on the frequency of the ambient noise.

ANC performance also depends on achieving a tight seal from over-ear cups or in-ear earbuds. In very loud environments, passive isolation remains important as well.

I have written a detailed guide analyzing whether noise cancelling headphones are worth the investment. This article looks closely at the pros, cons, and key factors to consider when deciding if ANC headphones are right for you. Make sure to check it out if you want to know more about the value proposition of noise cancellation technology.

And if you’re still unclear on the distinction between types of noise reducing headphones, my guide on noise cancelling vs. noise isolating headphones breaks down how the technologies differ. Check out this piece to better understand these two approaches to audio and when each is most effective.

How Do Noise Cancelling Headphones Work

Noise cancelling headphones use built-in microphones to detect ambient sound and generate inverted soundwaves that destructively interfere, reducing unwanted noise. Active noise cancellation technology analyzes and cancels sound in real-time, differing from passive isolation methods relying solely on physical barriers.

Several components work together in noise cancelling headphones to monitor ambient noise and generate the noise cancelling signal:

Microphones: Small microphones on the exterior of each ear cup monitor external noise across various frequencies. This allows the headphones to analyze background noise in the environment so it can be cancelled out.

ANC circuitry: Advanced digital signal processing (DSP) analyzes the sounds picked up by the microphones. It then mathematically generates inverse sound waves with the same amplitude but inverted phase to cancel out the ambient noise. This circuitry requires power to function.

Speakers: Once the inverse noise signal is generated, it is sent to the headphones’ speakers where it destructively interferes with and cancels out the incoming ambient noise. This results in only the audio signal you want to hear coming through the speakers.

Battery: Noise cancelling circuitry requires power, so most noise cancelling headphones have an internal rechargeable battery. Some may allow you to continue using the headphones passively when the battery runs out.

On-ear/over-ear design: Most noise cancelling headphones are physically designed to passively muffle some sound before active cancellation. This on-ear or over-ear style with closed-back ear cups provides physical isolation so the ANC doesn’t have to work as hard to block sound.

User controls: Controls like power and noise cancellation buttons allow you to turn ANC on or off as needed to preserve battery life or let in ambient sound. This lets you adjustable how much noise cancellation is applied.

How Do Passive Noise Cancelling Headphones Work

Passive noise cancelling headphones work by physically blocking external noise from entering the ear. This is accomplished through their over-ear cup or in-ear bud design which passively isolates the ear from outside sounds. Passive noise reduction does not analyze and cancel noise electronically.

How Do Active Noise Cancelling Headphones Works

Active noise cancellation works by using built-in microphones to detect ambient noise and generate inverse soundwaves that destructively interfere, reducing unwanted sounds. This real-time sound analysis and cancellation differs from passive isolation methods that rely solely on physical barriers to block noise.

Here is the step-by-step process:

Microphones on the headphones pick up ambient noise from your surroundings across a range of low frequencies. This includes droning sounds like engines or AC units.

The ANC circuitry analyzes the sound waveform characteristics of this ambient noise. It then inverts the waveform to generate an anti-noise signal of the same amplitude or loudness.

This inverted signal is shifted 180 degrees out of phase with the incoming soundwave from the environment. This anti-noise waveform has identical amplitude but inverted phase.

The anti-noise signal is amplified and sent to the speakers in each ear cup. The speakers play this phase-shifted signal.

When the original ambient noise wave meets the inverted anti-noise wave played through the headphones, the two identical but phase-shifted sound waves cancel each other out through destructive interference.

With the ambient noise wave eliminated, all that remains is the audio from your music or call carried over the headphone speakers. This allows you to hear clearly with background noise greatly reduced.

The whole process of analyzing, inverting, amplifying, and cancelling ambient noise occurs continuously and nearly instantly as you wear noise cancelling headphones. This real-time active cancellation means ANC can adjust and block out changing environmental sounds as you move through a noisy world.

How Active Noise Cancellation Works in Earbuds

Active noise cancellation in earbuds works by generating inverse soundwaves that destructively interfere with ambient noise, reducing unwanted sounds. Miniature microphones pick up environmental sounds to enable this real-time sound analysis and cancellation system.

Benefits of Active Noise Cancellation

Noise cancelling technology provides several key advantages:

  • Reduced distracting noise: By cancelling out ambient sounds, noise cancelling headphones greatly reduce distracting background noise that can disrupt work, reading, or music listening.
  • Improved audio clarity: With reduced distracting noise, the audio you want to hear through the headphones becomes much clearer. You can pick up more detail in music and accurately hear conversations.
  • Lower hazardous noise levels: For very loud environments like planes or construction sites, ANC can reduce the level of constant loud noise that could potentially cause hearing damage with prolonged exposure.
  • Increased concentration: The reduction in disruptive ambient noise can help increase focus when you need to concentrate in noisy environments where passive isolation isn’t enough.
  • Relaxation: The elimination of unpleasant ambient noise provides a calming, peaceful listening environment for many people trying to relax.

For these reasons, frequent travelers, office workers, and others often rely on noise cancelling headphones to provide a tranquil oasis of calm in even very noisy environments. The technology gives you control over your audio environment wherever you go.

Limitations and Considerations

Active noise cancellation isn’t perfect. There are some limitations and factors to keep in mind:

  • Works best on consistent low frequency noise: The technology is very effective at cancelling out steady, predictable ambient noise like engines. But it may struggle with voices or irregular spikes in volume.
  • Can’t cancel all noise: There is a limit to how much active cancellation can reduce background noise, usually about 20 decibels. Very loud environments may still be distracting.
  • Audio leakage: Some noise still leaks out of headphones and in from outside. ANC works best when you achieve a tight seal with on-ear or over-ear models.
  • Power required: Noise cancelling headphones must have an internal battery charged up to function. Make sure to charge them when not in use.
  • Pressure sensation: Some people feel a slight pressure or sense of motion sickness from the sound created by ANC to cancel noise. Newer models minimize this effect.
  • Expense: Quality noise cancelling headphones tend to cost more than passive models due to their complex internal electronics. Look for sales on premium brands.

Why Can I Still Hear With Noise-Cancelling Headphones?

While very effective at reducing ambient noise, noise cancelling headphones cannot completely eliminate all external sounds. Their performance is optimized in consistent noise environments like airplane cabins.

More unpredictable noises like voices can be more challenging for the technology to cancel out fully. Some sound leakage and external noise will still reach your ears even when using noise cancellation.

Higher quality noise cancelling headphones with more advanced microphone and processing systems tend to cancel more ambient sound overall.

But no current consumer models can entirely mute the environment. Expecting a significant reduction of distracting background noise is a more realistic goal when using noise cancelling headphones.

How Active Noise Cancellation Has Evolved

The concept of using destructive interference from inverted sound waves to cancel noise has been around since the 1930s. But early systems were bulky, high power, and expensive. Advances in digital signal processing starting in the 1990s allowed practical application of ANC in consumer headphones. Timeline highlights include:

  • 1980s: Noise cancelling is first applied in airplane and helicopter cockpits to improve communication clarity.
  • 1989: Noise cancelling technology used in headphones for the first time by Bose.
  • 1995: First in-ear noise cancelling headphones introduced, but required large battery packs.
  • 2000s: As DSP chips get smaller and more efficient, on-ear and over-ear ANC headphones grow popular with prices coming down.
  • 2010s: ANC expands beyond audiophile brands, with mass market headphones at lower prices. Processing improves to minimize audio artifacts. Wireless and true wireless models introduced.
  • 2020s: Headphone makers compete on DSP algorithms and number of microphones to improve ANC performance. Noise masking and transparency modes added for flexible listening.

Overall, as digital signal processing technology improves, active noise cancellation is getting better and available in more affordable products.

This has moved ANC from professional and niche use to the mainstream for consumers in noisy environments. More advanced ANC algorithms continue to develop, using AI and machine learning to analyze and cancel noise in innovative new ways.

The Future of Active Noise Cancellation

The global noise cancelling headphones market is predicted to expand at a CAGR of 5.7% between 2022 and 2032, with sales estimated to reach US$ 9.06 billion by the end of 2032 according to a report by FactMR. This growth demonstrates rising demand for noise cancellation capabilities in headphones.

Noise cancelling technology will continue advancing in the coming years. Some future directions include:

  • Improved noise cancelling and isolation: More microphone arrays and faster processing will improve noise analysis and cancellation accuracy in real-time across more frequencies. Physical headphone isolation will also progress with new materials.
  • Personalized cancellation profiles: Future headphones may analyze the user’s ear shape and adapt noise cancellation waveforms for optimal individual performance.
  • Situational awareness settings: Instead of fully blocking external sounds, settings like transparency mode will allow users to remain aware of select noises like alerts and speech.
  • Power efficiency: Better DSP chip design and battery technology will increase noise cancellation playback times when untethered. New lower power processing approaches are also being researched.
  • Alternative form factors: ANC may expand from over-ear designs to more discreet earbuds and smaller on-ear options without sacrificing performance.
  • Noise cancelling panels and environments: Large noise cancelling speaker arrays could one day silence entire rooms or vehicle cabins instead of just headphones.

Optimizing ANC for Travel Scenarios

Noise cancelling headphones really shine while traveling. Turning on ANC helps immerse in entertainment or focus amidst noisy engines and crowds. Be aware it consumes more battery life.

For long haul flights, adaptive ANC responds well to low rumbles and high chatter by cancelling both frequency ranges. Overall, ANC grants travelers an oasis of calm.

If you have concerns about potential health impacts and are wondering are noise cancelling headphones safe, I have an in-depth article comparing noise cancelling vs. noise isolating headphones. This guide discusses hearing health considerations and differences between the two technologies. Give it a read if you want to learn more about these audio solutions.

Do ANC headphones completely eliminate noise?

No, though they significantly reduce it through anti-noise generation. Some sound still slips through, especially in unpredictable environments. Performance depends on headphone quality and fit.

How does ANC differ from noise masking?

ANC cancels sound waves with inverse ones. Masking adds other sounds to obscure noise. Both reduce what you hear but work differently.

Why do I still hear some noise with ANC?

ANC works best in consistent noise environments. More unpredictable settings challenge the technology, so some sound gets through. Higher-end models with better microphones tend to cancel more noise.


Noise-cancelling devices contain built-in microphones that detect ambient sounds and generate inverted soundwaves. The inverse waves destructively interfere with external noise, cancelling the sounds. This active noise cancellation differs from passive isolation methods that physically block noise.

Similar Posts

Leave a Reply

Your email address will not be published. Required fields are marked *