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How do noise-cancelling headphones work?

It’s been just over twenty years now since Bose introduced the first active noise cancelation (ANC) headphones, the QuietComfort. Since then, the technology has advanced leaps and bounds. Virtually every manufacturer now offers headphones or earphones that pledge to eliminate background noise from your listening experience.

Some are far more successful than others, and the most effective ANC headphones are almost guaranteed to become best sellers. Whether you want to cut out the noise of your daily commute, the background chatter in your office, or the construction site next door, noise cancellation headphones are a must.

So, how do noise-cancelling headphones work?

In this article, we’re going to take a look at the science behind noise cancellation headphones, and how it’s put to use. We’ll start by taking a look at how this all came about, and the potential benefits of cutting out ambient noise.

A Brief History of Noise Cancelling Headphones

 

A Brief History of Noise Cancelling Headphones

The first noise-cancelling headphones were designed for use by pilots in the airline industry who rely on clear communication to do their job safely. Long-term exposure to constant loud noise has also been proven to cause permanent hearing damage, and the last thing you want is a pilot with compromised hearing.

The first commercial noise-cancelling headphones were marketed at frequent flyers to also cancel out the noise of jet engines, thereby making flights more of a comfortable and stress-free experience.

The technology has since been adapted to help filter out the background noise of any environment you may find yourself in; for most, these will be busy urban settings.

The ability to quieten the roar of traffic…

Along with the noise of commuters or the chatter of your average office has numerous positive benefits. From increased productivity and concentration levels to reducing stress and thereby improving health. These are just a few examples of how noise canceling headphones help you work.

There’s also the bonus of protecting that most vital of human senses, your hearing. Read on, and you shall see how noise canceling headphones can protect hearing.

Passive Noise Isolation

All headphones naturally provide a level of sound reduction by their very nature. This is known as passive noise isolation. The physical barrier they create between the outside world and your ears will have a muffling effect on external sounds.

Design plays a big part in how effective this isolation will be. But even the best models can only achieve a maximum of 15-20dBs of noise reduction. In noisier environments, all that excess noise invading your ears can lead many people to raise the volume to dangerous levels, putting their hearing at risk.

This is where active noise cancellation can come to the rescue.

Active Noise Cancellation

Active Noise Cancellation

As you may remember from science class, sound is made up of waves. The length of the wave determines its frequency, and the height of the wave measures its amplitude or volume.

Headphones with active noise cancellation use technology to generate soundwaves of the same frequency and amplitude as the ambient noise. If these sound waves were in sync, it would result in a bigger wave and an increase in volume.

The trick is to delay the generated sound wave by exactly one-half wavelength, thereby matching the peaks against the troughs rather than the peaks with the peaks. This effectively nullifies the incoming sound, with the desired result being silence. Add 1 to -1 and vice-versa, and you end up with 0.

How do noise-cancelling headphones work?

ANC headphones use tiny microphones which pick up ambient noise and deliver it to an audio processing chipset. The chipset then uses an algorithm to create a similar yet inverted sound wave. It then feeds to the speaker in the headphone, thus canceling out the original sound wave.

Unfortunately, it’s not quite as straightforward as it sounds. If it was that simple, active noise cancellation would be 100% effective, and its implementation and development would have reached that level a long time ago.

Sound is a complex entity…

Very rarely does it come in one predictable and stable wave. The microphones and circuitry have to work in real-time to invert a wide range of constantly changing sound waves, especially in busy urban environments.

ANC will be most effective when dealing with constant sounds that have a relatively steady wave. That’s why they work so well to block out sounds like airplane engines or AC units.

They have a much harder time trying to cancel sounds that are unpredictable with a lot of variation in volume and pitch. Somebody singing or random construction noises, for example. Higher frequency sounds are also much harder to make adjustments to.

Not a perfect art…

So, how much noise can ANC headphones block? Effective noise-canceling headphones block out up to 20dB of ambient noise. That on top of any passive noise isolation capabilities the headphones already possess.

Noise Cancelling for phone calls…

The same technology can also be used to improve the clarity of phone calls. Unwanted background noise will again be reduced. As a result, your voice comes through as clearly as possible on the other end.

Scrambling to find a quiet spot to make yourself heard, and to hear the other person, is quickly becoming a thing of the past with quality ANC headphones.

The Drawbacks of Noise Cancelling Headphones

Drawbacks of Noise Cancelling Headphones

Whilst there are numerous benefits of using ANC headphones, there are also a few drawbacks.

Expense

Although you are now starting to see cheaper models, which include ANC, the best performers are significantly more expensive than comparable standard headphones. Be prepared to splash out if you want the highest levels of noise cancellation.

Battery Life

All that microphone and processing technology requires power. With ANC turned on, you can expect a 20-25% reduction in the full charge battery life of the headphones.

Sound Quality

With all that tech running, there is often a slight dip in the overall sound quality of ANC headphones. Leading to a slightly less natural sound. The best models have gone a long way to addressing this issue, but as audiophiles will be keen to remind you, they haven’t fully closed the gap.

Looking for some great Noise Canceling Headphones?

We have plenty of high-quality ANC headphones and earbuds for you to choose from. Check out our in-depth Sony WF 1000XM3 review, our Bose QuietComfort 35 II review, our Best Noise Isolating Earbuds review, our Razer Hammerhead True Wireless Pro Review, and our AKG N60NC review for awesome items you can buy in 2021.

You might also like our comprehensive Shure SE215 BT2 Review, our Best Bluetooth Headphones for Commuting review, our Bowers & Wilkins PX Review, our JBL E55BT Review, and our Jabra Elite 85h Wireless Noise-Canceling Headphones Review for more incredible items currently available.

How do noise-cancelling headphones work? – Final Thoughts

The best active noise canceling headphones have come a long way since the earliest models twenty years ago. Whilst the technology is nowhere near perfect; it has become an integral part of the audio experience of millions.

The ability to block out the hustle and bustle of the daily commute is the number one reason most people have made the move to ANC headphones. With urban areas as noisy as ever, you can be sure many more will follow.

Not only will their trip to work involve significantly less stress, but good ANC headphones will also help to spare their hearing from unnecessary damage. If you can afford the higher price tag, making the move to active noise-cancelling headphones is a no-brainer.

Until next time, happy listening.

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About Corey Hoffman

Corey is a multi-instrumentalist who has played in numerous bands over the years, some good, some not so good. He has also written countless songs and recorded five albums in professional studios across America. Today he is a hobby musician but still loves the guitar after over 15 years of playing.

He considers his writing as a way to share what he has learned over the decades with younger generations ad always can't wait to get his hands on the latest gear.

He lives just outside New York with his wife Barbara and their two German Shepherds, Ziggy and Iggy.

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