We’ve all heard of them sometimes. The headphones with noise cancellation technology are ideal for traveling and, although they are not exactly cheap they offer significant isolation from the noises around us and a premium quality sound too. You can check our list of top 10 best noise-canceling headphones under 100 dollars.
But have you never wondered how headphones get to cancel external noise? What wonder of technology intervenes so that we can avoid the noise around us while we are traveling especially? In this article, we will explain how noise cancellation works.
Types of Noise Cancellation
There are two technologies currently available: Passive noise cancellation and active noise cancellation. The first is based on using insulating materials that reduce noise and the way it adapts to the ear. Any in-ear headset is already reducing external noise to a greater or lesser extent because the earbud is inserted inside your ear.
The active noise cancellation, on the other hand, uses a more sophisticated system and the electronics come into play to make a more effective cancellation.
1. Passive Noise Cancellation
It is the technology that gives mediocre results, but the advantage is that it is much cheaper to implement. The cheapest headphones use this technique since those, which use the passive noise cancellation, are from about $100.
The cancellation of passive noise, in fact, fails to cancel external environmental noise, but really what it does is an attenuation. This attenuation can reach different values in decibels that usually range from 8 dB to 25 dB in some cases.
This value depends largely on what materials are used to isolate the noise and how they fit the ear. The usual drawback is that it does not filter the noise of certain frequencies well and good noise attenuation is not achieved, especially at low frequencies.
2. Active Noise Cancellation
For best results, we must go to active noise cancellation. This technique makes use of a microphone that is integrated into the headset and that captures the noise outside. This sound is sent to the integrated noise cancellation circuit. These headphones are a must-have gadget for your kids when they are traveling with you.
What this chip does, is to create an inverted wave of the captured sound, to create an out-of-phase wave and cancel the original wave. This happens, because if one wave is picked up and another one is taken the same but in the opposite direction to the first one, that is to say, the inverted external sound, these waves will be canceled or as they say, they are out of phase. Thus, only the music played by the headset would be heard.
Noise cancellation in the headphones, how does it work?
First, and before getting into the matter, it should be noted that this time we are talking about active noise cancellation technology, that is, the one in which electronic components are involved. Active technology, the one that manages to reduce external noise, has the most curious operation.
The first thing that will surprise you is that these headphones incorporate a microphone into their design. And we are not talking about the microphone that in some cases bring the hands-free headphones, but it is a small microphone inserted into the design whose sole mission is to capture the sounds that surround us while we have the headphones on.
Well, but how the headphone identifies the music and external noise?
There comes into play something similar to a processor. This chip collects in real time the sound captured from the outside and, immediately afterward, gives the speakers the order to emit in the background while we listen to our music the sound captured outside with a 180-degree offset of the original wave. You can read the complete detail of noise cancellation technology on BeatsInside.com.
What this technology does is to match the sound waves that the microphone picks up oppositely. If a wave is very high, the speaker emits exactly the opposite wave; that, applied to all the oscillations in the sound wave that the microphone receives, translates into noise cancellation. In somewhat more technical terms, all this technological wonder is explained by the so-called acoustic phase. And if you have ever tried headphones of this type, you will remember that with the active noise cancellation you hear a strange little buzzing when no song is being played. That noise, indeed, is that of the speakers doing the noise cancellation job.