How Do Noise Cancelling Headphones Work?
Noise cancelling headphones are popular these days, and for a good reason.
They block out external noise, drowning out almost everything around you to give you the kind of listening experience open back headphones never can.
Built to cancel even the loudest noise, these headsets create an environment free from distraction, allowing you to get the most out of your audio or video playlist.
But how do noise cancelling headphones work in the first place?
In addition to answering this question, we’ll outline the pros and cons of using this kind of headsets. In the end, you’ll see why they are more popular than the competition.
But first things first:
The History of Noise Cancelling Headphones
While noise-cancelling headphones are popular today, crowded in every market that deals in electronics, the concept dates back to 1978.
During his flight from Zurich to Boston, Dr. Amar Bose became frustrated because his electronic headset couldn’t manage the noise of the plane and give him a better listening experience.
It’s during this flight that the idea of designing headphones that could block out ambient noise was born.
However, it took 8 years, millions of dollars in investment, and a lot of time in research to come up with the first prototype.
This headset was a beast, worked exactly as expected, and it became popular among militaries, airplane pilots, and first and business class customers of American Airlines.
Noise cancelling technology was somewhat expensive at the time. Which means that the public couldn’t afford to secure them.
But as cost went down overtime, these headphones became readily available for everyone to buy.
From the time this technology went public to this very day, the goal has been to allow you to listen only to the sound that matters.
Types of Noise Cancelling Headphones
There are only two types of noise-cancelling headsets since their invention: passive and active.
1. Passive sound blocking headsets
They are made of high-density foam and sound absorbing materials, which makes them somewhat heavy compared to regular headphones.
Despite their weight, they reduce high frequency sounds really well, reducing external noise by up to 20 decibels (dB).
The most common example of headsets in this category is the best headphones for kids. They do block out some level of noise, allowing your young one to immerse themselves fully in their own listening experience.
2. Active sound blocking headsets
These ones are more powerful than the passive type. In addition to blocking high frequency sound waves, they also erase lower frequency sound waves on the go.
Designed to provide an additional noise reduction to a tune of 20 decibels, this kind of headset can easily block more than 60% of ambient noise generated by an aircraft’s cabin.
This, in my take, explains why active sound blocking headphones are the ideal option to consider for travel.
Understanding the Physics: How These Headsets Cancel Noise
Every headset in this category creates a sound that imitates external noise.
In essence, there are two sound waves involved in the process: one from the noise cancelling headphones and the other from external ambient noise.
The sound wave coming from the headphones is 180 degrees out of phase with the incoming noise. And both have a similar amplitude and frequency.
Because the two waves are out of phase with each other, they create a destructive interference, and then cancel each other. The result is a more improved audio experience, as you can now listen to what you actually want to hear.
How to these Headphones Manage to Cancel Out Noise?
Every active noise-cancelling headset has four components that make the process of blocking out noise possible.
These are a microphone, a noise-cancelling circuitry, a speaker, and a battery.
Sandwiched inside the ear cup, the microphone listens to high and low frequency sound waves, which is simply noise that’s hard to cancel out passively.
Located just adjacent to the microphone, this electronic device senses the input from the mic.
Then, it traces the noise, taking note of the frequency and amplitude of the incoming sound wave.
This noise eraser goes even further to create a completely new wave, which is 180 degrees out phase with the incoming ambient noise.
The sound blocking circuitry creates and feeds an anti-sound and a normal sound to the speaker.
Given that the new wave is out of phase with the external noise, the two cancel each other.
Keep in mind that this process does not have an effect on the sound frequency of your normal audio.
And the result is an exceptional sound out of your music, which means you get an outstanding listening experience from this kind of a headphone.
For a headphone to cancel out noise, it must have an active source of energy. This is why they have a built-in rechargeable battery.
The Benefits of Noise Cancelling Headphones
The following are some of the advantages of using passive and active noise blocking headphones.
1. You get a better audio experience
Normal headsets like Sony Clip-on Stereo are inexpensive. But they can only be effective in not-so-noisy environments.
Bring them to an extremely raucous scene and you’ll notice just how disappointing they can be.
Active sound blocking headphones are the real deal when you seriously want to cancel out all noise from around you.
Designed to improve audio output and effectively withdraw all kinds of external noise, these headsets give you an up to standard listening experience normal headphones never can.
Whether you are in an airplane, a noisy street, or an extremely deafening constriction site, these headsets should give you a noise withdrawal level that you need for an exceptional listening experience.
2. They enhance the quality of your conversation
There’s nothing worse than making or answering a phone call using headphones in a noisy place only to realize that you can’t connect with the person on the other end.
You’ll struggle to hear the caller on the other end. They, too, will strain to listen and understand what you have to say.
Those “excuse me”, “I can’t hear you”, and “I’m sorry I didn’t get that” are merely but because of using normal headsets to make calls in extremely noisy places.
Active sound blocking headsets are different. Because they clear out ambient noise on the go, they let you make and receive calls without a hassle. This way, you and the person on the other end are able to hear each other clearly.
3. Good option for improving sleep quality
While getting enough sleep is important, not everyone is lucky to close his or her eyes for 8 to 9 hours straight.
And the culprit is a continually disturbing noise from all around you.
Whether you live in a noisy neighborhood or share a bed with a snoring partner, you know just how hard it can be to finally close your eyes and sleep until daybreak or sunrise.
Get some noise-cancelling headphones for sleeping.
An active type is a good option to choose. Passive ones should also work fine because they also cancel out as much noise as possible.
If you’re the kind of sleeper that turns and toss from time to time, over ear headsets may not be helpful nearly as much. In such a case, you might want to consider earbuds for sleeping because they tend to stay in position throughout the night.
4. They can protect your ears from damage
Repeated exposure to extremely loud environments can damage your ears and probably lead to hearing loss.
That’s why it’s important to use sound blocking headsets in places with noise levels exceeding 75 decibels.
Passive noise blocking headsets, when worn to proper fit, can reduce noise by up to 20 decibels. You may still hear some external sound from them, but it’s usually insignificant.
Active noise-cancelling headphones, on the other hand, can reduce noise by up to 80 decibels.
If you were in an environment with 85 decibels of noise, for example, these headsets would leave only about 5 dB, which is often equal to the sound of a whisper.
Their ability to draw out the ambient noise from an airplane’s engine makes them more than ideal for air travel.
Disadvantages of Noise Cancelling Headsets
The following are some of the most common drawbacks of using headphones built to cancel out noise from your surroundings.
1. These headphones are expensive
Ambient noise blocking headsets are some of the most expensive electronics that I’ve ever seen.
I mean, think about it for a second.
The concept requires additional components not found in regular headphones. Which is to say that they demand a lot more resources to design unlike their low-end counterparts.
Take Boss 700 with Alexa Voice Control, for example. Going for over $300, they’re some of the priciest models the company has ever created.
On the other hand, they work great, giving you an outstanding audio experience that cheaper option with the same kind of technology still struggle to offer.
The bottom line is this:
If you seriously want to own high quality headphones that can truly cancel out ambient noise, then you should be ready to dig deep into your pocket.
2. Using them makes you unaware of your surrounding
I can appreciate the true value of noise-cancelling technology in headphones. The drawn out noise, the improved audio experience, expected sound clarity, are all great.
But here’s the problem:
These headphones completely rip you away from your surroundings, making your unaware of what’s going on around you. And this can be dangerous.
My advice is this:
Use these headsets only when it’s appropriate. To be on a safer side, don’t use them while walking, cycling, or driving.
Also, don’t use them at work and if you must, make sure you inform people around you that you need some alone time.
3. Their battery life is terrible
The noise blocking process depends on a built-in rechargeable battery. But the mechanism seriously guzzles a lot of energy, giving you a very short runtime.
At the very least, many of the most popular headphones in the market offer a battery life of around 20 hours.
This, of course, may not be an issue for most people.
But if you’re the kind of person who would rather have these working 24/7, then you’ll have to charge them frequently.
Please keep in mind that since noise blocking technology work better only in an environment with consistent ambient noise, they won’t cancel out every single noise.
Noise like people talking loudly, trains hooting, and cars honking are inconsistent. And as such, a bit of it may leak through to your ears.
But then again, the noise shouldn’t be deafening or annoying.