How Do Noise Cancelling Headphones Work

How Do Noise Cancelling Headphones Work

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If you’re a commuter, or someone who travels by airplane often, someone has certainly told you at some point that active noise cancelling headphones are a must.

If you aren’t big into headphones, you might be wondering what they are, how they work, and whether you should be considering them as your next pair of headphones.

To answer those questions, we’ll be taking a look at a few things. We’ll start off with how conventional headphones offer noise isolation, and then we’ll move to active noise cancelling options and everything that surrounds them.

Noise Isolation vs. Noise Cancelling

Aren’t all headphones noise cancelling?

Well, to some extent, yes. However, there’s a major difference between active and passive noise cancelling headphones.

If a pair of headphones isn’t explicitly advertised as being active noise cancelling, it’s probably a passive one.

The thing with passive noise cancelling is that the only isolation you get is from the eartip resting in your ear canal, or the ear pads pushing on your head.

There is nothing more than that, and the level of isolation basically depends on the fit and materials of choice. Yes, this does offer some level of noise cancelling, but in many situations, it’s nowhere near to drowning out loud environmental noises. And this is where active noise cancelling comes in.

What Is Active Noise Cancelling

Active noise cancelling headphones have a technology inside them that actively cancels out any external noises.

This is why in many scenarios, they can reduce outside noise by as much as 30 decibels, allowing you to enjoy your music without any distractions. This is especially key when you’re flying, as airplane engines are notoriously loud.

To understand how they work, let’s talk about sound and what sound is first. When you visualize sound, it’s in the form of a wave.

Hearing sound is basically compressing and decompressing particles in the air. Moving those particles results in changes in air pressure, which we call amplitude.

And those changes in pressure are detected by your ears and brain, and are deciphered as sound. If you put that amplitude on a chart, you get the wave we spoke about.

Noise cancelling technology works by using a thing known as “anti-phase”. Let’s take the environmental sound and look at it as a wave. When you add another wave, identical to that one, you get an even larger wave, and a louder sound.

However, if you were to delay one of the waves by exactly one half wavelength, you will find that the waves are out of phase. They subtract from one another, just like if you had one and negative one. And what do you get when you add both? That’s right, zero. This is how noise cancelling works.

When you have headphones with active noise cancelling, they come with multiple tiny microphones on the outside of the headphones themselves. They’re responsible for recording everything that happens outside, and forwarding it to the electronics inside the headphones.

Those electronics then add the exact opposite to the sound wave (which is known as the anti-phase), which basically cancels out the noise coming out from the outside. At the end, all you’re left with is the sound you want to hear from your headphones.

Of course, theoretically, this all sounds like it’s rather easy, right? But in practice, noise cancelling is a very difficult thing to get right, and even the best options are far from perfect. To add to this, it doesn’t work well in any environment.

The low hums like an airplane’s jet engine are usually easy to cancel, but that’s not the same with random sounds, like a person talking next to you. Of course, this will all change as the technology evolves.

Should You Get a Pair?

should you get noise cancelling headphones

This is probably the question that brought you here in the first place. And the thing is, the answer completely depends on your specific use case. It depends on how much you want to spend on a pair, and it depends on where you’ll be using them and how.

The first thing we should address is the price. Considering this is a difficult technology to get right, the price for a pair of active noise cancelling headphones is rather high. And it becomes even higher as you take a look at higher quality models with better sound quality, and better noise cancelling. There’s no denying that not everyone can afford an expensive pair of headphones.

Then there is the use case. In many situations, even the best active noise cancelling headphones won’t completely drown out all external noises.

This happens, as we mentioned, in environments where you have random noises that an algorithm can’t predict, such as a loud office setting where people talk all the time. Yes, they will definitely help, and they’ll reduce most of the noise, but they won’t drown it out completely.

To add to this, many people wonder whether or not they’re good for commuting. In most situations, yes, they’ll drown out most of the external noises and allow you to completely focus on your music.

But if you’re in traffic, whether it’s on a bicycle, or as a pedestrian, or in any other capacity, do you really want to drown out your environment?

You should be able to pay attention, and while active noise cancelling headphones will drown out external noises, that’s not something you want happening.

Last but not least, if you’re someone who travels by train, or in the subway, or on airplanes, pretty often, a pair of good active noise cancelling headphones are definitely worth it.

You can relax and enjoy your music, without being forced to listen to the noise of the railways or the airplane’s engines.

As we mentioned, it’s all a matter of whether or not they fit your use case. And if they do, by all means get a pair, you’ll be surprised as to how good they are, and how much of a difference they make.  

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