How Do Noise-Canceling Headphones Work?


Noise-canceling headphones, also called active noise-canceling headphones, use electronic processing to analyze ambient sound and attempt to generate the “opposite” sound. The result is less noise overall.

What Are Noise-Canceling Headphones?

Noise-canceling headphones are a special type of headphones that minimize unwanted ambient sounds entering your ear through active noise control. Their obvious advantage lies in their ability to reduce unwanted noise and enhance the overall listening experience.

Listening to music with noise-canceling headphones is a wonderful experience, as they enable you to listen to music without having to increase the volume to uncomfortably high levels (which can negatively affect your ears and hearing). These types of headphones are also used by aircraft crew to listen to vital announcements and other pieces of information with much more clarity in the noise surrounding an aircraft.

Noise-canceling headphones were designed to accomplish one thing and one thing only– cancel noise, or at the very least, muffle it so much so that it becomes harmless. Every other thing they do is dependent on how well they can rid us of the noise. But apart from the promise of relief and quiet that noise-canceling headphones promise, what other benefits are there to it? What are the disadvantages that come with being able to “cancel’ noise and how much harm do these disadvantages cause us?

In light of all these, it might be helpful to break down the pros and cons of owning and using a noise-canceling headphone; that way current users can become more aware and more cautious while future users can become less naive and more prepared.

PROS

It Helps To Boost Your Concentration:

Noise does more harm to your concentration, output and by extension, your productivity and satisfaction much more than you realize. For quite some time now, researchers have suggested that noise, especially loud intermittent noise, reduces our cognitive performance.

Better for your ears:

Exposure to noise for an extended period has been found to pose serious threats to human health, threats ranging from cardiovascular diseases, sleep disruption and deprivation, to brain damage, to noise-induced hearing loss and tinnitus, etc.

If you must remain in a noisy environment that puts you at risk for these diseases then you should consider investing in noise-canceling headphones.

Noise Canceling Headphones Can Reduce Stress:

When you are constantly exposed to high-level noise, as most city dwellers are, it can increase your stress levels. The Journal of the Acoustical Society of America released a study that looked at the effect of high-level noise such as train and car traffic on children.

The study showed that children who lived in neighborhoods with constant background noise had a higher amount of cortisol which is the body’s stress hormone, compared to children in quieter neighborhoods. The effect of this constant stress can be quite serious.

Another 2006 study showed that people with constant low-level noise exposure were more likely to suffer heart attacks. By wearing noise-canceling headphones while walking the streets or even when you are home in your apartment you will create a stress-reducing environment. People who use active noise-canceling headphones typically note a reduction in their feelings of stress and anxiety.

Toggleable Cancellation:

Perhaps you don’t want to cancel out the outside world all the time. Perhaps you want to hear your surroundings, then turn the cancellation on when you’re in transit or the neighbors get noisy.

Active noise-canceling headphones typically have a switch that turns the cancellation on and off. This means you can turn it off when you want to hear the doorbell and turn it on when it’s time to zone into a game. This is better than regular headphones and passive cancellation.

Improve The Quality Of Your Sleep:

According to the National Sleep Foundation, 62% of Americans experience problems sleeping at least a few nights a week. One of the leading causes of sleep problems is ambient noise. This noise might come from a snoring partner or a noisy neighborhood but the results are the same – another sleep-deprived night.

Removing the noise with noise-canceling headphones can allow you to enjoy quality sleep even in a relatively noisy environment. One of the most popular uses of these headphones as a sleep device is for plane travel.

CONS

They Are Expensive:

As the adage goes: you get what you pay for, this particularly holds for noise-canceling headphones because they definitely do not come cheap, some of them like the new Bose 700 would set you back by as much as $400.

They Make You Unaware Of Your Surroundings:

For safety reasons, it’s not advisable to wear noise-canceling headphones when you’re on the road, because it blocks out noises such as car horns, train horns, and sirens and makes you unaware of your surroundings. You won’t even hear when people are shouting for you to get out of the way.

4. Short Battery Life

Because of the work they do, noise-canceling headphones tend to consume a lot of power, for most of them (provided your device is in best condition) you only get about 20 hours of uptime before your battery goes flat

And when your battery empties, you’re left with just a normal headphone without noise-canceling abilities.

Who Needs Noise-Canceling Headphones?

If you are a frequent traveler, good noise-canceling headphones will make any journey in a plane, train, or automobile far more enjoyable. In-ear models are easier, though still slightly uncomfortable, to sleep with. Over-ear models reduce a little more noise as they can passively block some sound because of their design, but they are always bulky on your head or in your bag.

However, if you rarely travel, or you find higher-frequency noises like people talking, cars honking and noisy neighbors more annoying than airplane engine noise or background chatter, these headphones may not be worth it. Cheap earplugs, or perhaps noise-isolating earbuds, might work well enough. And it’s worth keeping in mind that for the same money, regular headphones will likely sound better than noise-canceling headphones.

How (And When) Noise Canceling Headphones Work?

Noise-canceling headphones seem like an oxymoron: a piece of audio technology that creates silence, rather than noise. They’re useful on planes, in crowded offices, and for light sleepers trying to catch some shut-eye in a thin-walled apartment, but how can a pair of headphones make sound disappear?

The first component of noise-canceling headphones’ formula for success is passive noise control or the slightly more sophisticated technological equivalent of putting your hands over your ears to block out incoming noise. Certain earbuds or headphones are shaped specifically to physically prevent sound waves from reaching your ears; these are the types generally marketed as “noise-isolating.”

Whether by creating a closer external seal around your ears and using sound-absorbing material like high-density foam, as in the case of headphones or simply fitting better into the shape of your ear canal, as in-ear buds do, noise-isolating accessories can block up to 20 decibels of background sound.

When 20 decibels of quiet won’t quite cut it, noise-canceling headphones step in with active noise control or ANC. Pioneered by MIT graduate and Bose Corporation founder Amar Bose and inspired by the intolerable loudness of jet engines on a transatlantic flight, ANC technology is what distinguishes noise-canceling headphones from noise-isolating headphones. Rather than simply preventing unwanted outside sound from reaching a listener’s ear, ANC uses “destructive interference” to cancel out ambient noise.

The process involves placing a microphone as close as possible to where sound will be entering the ear, which will pick up on the frequencies of the incoming noise; the headphones will then generate a frequency exactly 180 degrees out of phase with the unwanted noise—an “anti-noise” output that directly cancels out the input. While ANC is most effective at lower frequencies, noise-canceling headphones can reduce overall noise by up to 80 decibels—just about the amount of irritating background racket produced by commercial jet engines, so you can get at least some peace on your long-haul flight to wherever.

Imagine ocean waves. There’s a high part, the crest, and the low part, the trough. If you combined the positive height of the crest and the negative depth of the trough, the result would be a flat sea. Or for the math inclined, if you add +1 and -1 you get 0. This is essentially what active noise-canceling headphones do. Add troughs to crests and crests to troughs. Except instead of seawater, it’s sound waves.

It’s not perfect. these headphones don’t “create” silence, nor are they able to eliminate noise. The crests and troughs do not perfectly cancel out. The absolute best noise-canceling headphones merely reduce noise and work best with low-frequency droning sounds. So a loud hum is a quieter hum. The roar of an airplane is a quieter roar on an airplane.

They also don’t work well for all sounds. At higher frequencies, like the human vocal range and higher, the headphones do very little if anything at all. So if you hope to block out the cries of the baby in seat 15C, you’re out of luck. Fast and transient sounds, like a door slam or a hand clap, also aren’t blocked effectively.

What’s perhaps even more frustrating is not all noise-canceling headphones work the same. The best reduce a lot of noise, the worst reduces very little or nothing at all. There’s no way to tell, looking at a headphone’s specs, which are which.

Noise-canceling headphones require a battery to power their electronics. Noise-isolating headphones, which do not require electronics and therefore can be far cheaper, work by creating a seal in your ear canal to block noise. They are like earplugs, but with earbuds inside. If you can get a good seal, these work reasonably well.

Getting a good seal can be a challenge, however, since everyone’s ears are different and not all headphones will fit correctly. And even if you do get a good seal, noise-isolating headphones will not be able to block low-frequency sounds as well as the best noise-canceling headphones. They will reduce a wide range of frequencies, which can help.

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