Whether you're a music lover or just trying to make a phone call in a loud environment, you know how frustrating it can be to have to deal with lots of ambient noise. If you've had the fortune of using a noise cancelling headset, then you know just how powerful this feature can be. There is nothing better than popping on your favourite set of headphones and being isolated from the busy world around you. Music seems to rise up from total silence, and your phone calls come across loud and clear. While noise cancelling is a very popular feature these days, not many people understand just how advanced the technology is that goes into these headsets. Let's take a look and see how this feature works.
Types of Noise Cancelling Technology
When it comes to choosing a noise cancelling headset, there are two different options available to you. The most affordable type of noise cancelling is passive. These headsets are designed to physically isolate you from the sound outside, reducing the amount of sound that can enter your ear canal. Active noise cancelling is a little more advanced. This technology is adaptive, meaning it responds do your environment. When there is a loud sound, it actually changes its environment to counteract the sound wave. If we're going to understand this technology, we'll first need to understand how sound works.
How Sound Works
The sound is created by physical movement in the air. When you pluck a guitar string, the string vibrates and pushes on the air around it. These vibrations travel through the air and enter your ear canal, eventually pushing your ear drum in the same manner. Because sound is a physical movement, it's affected by obstructions. Sound can still pass through solid objects such as a wall, but the sound wave will be modified and reduced, making it hard to hear.
Passive Noise Cancelling Technology
Sound travels through some materials better than others. Generally, hard objects tend to vibrate with sound waves, allowing sound to pass through. Soft objects tend to "absorb" the sound waves, muffling them. Passive noise cancelling works by physically isolating your ears from the outside environment. In a way, every headphone on the market provides some degree of passive noise cancellation. But models that are marketed with this feature are much more advanced. They use a special combination of materials that prevents sound from penetrating the headphone. Often, the ear cups are coated with an absorbent material.
Active Noise Cancelling Technology
Active systems are considered the gold standard of noise cancellation technology. When a sound wave hits the earcup of your headphone, a portion of it will be transferred through the material. Active cancellation, on the other hand, changes the way that sound is produced in order to reverse unwanted sound waves. Headphones work by vibrating a membrane in a manner which produces sound. With active noise cancelling, a small microphone picks up all of the outside noises. When a sound wave hits the microphone, your headphones move the membrane in a matter opposite to this soundwave – effectively cancelling it out. Noise cancelling circuits have to be carefully tweaked to move the drivers in the exact manner needed to correct sound waves, at the exact time. Response time is often a tiny fraction of a second. Something that seems simple in principle actually requires very advanced calculations. Fortunately, we live in an era where these calculations can be performed by a tiny little chip, giving almost everyone access to this crazy feat of engineering.