You will learn “how does noise canceling headphones work” in this guide!
Active noise cancellation is a fascinating feature of high end headphones. There requires some rather complicated engineering headphones, such as these are able to eliminate or destroy unwanted noise that’s produced by the external environment while simultaneously playing the desired music or audio that’s sent from your smart.
How does noise canceling headphones work?
Noise canceling headphones work by using a microphone to measure the unwanted noise produced by the environment. And then calculating an anti-sound wave. This anti sound wave is added to the wave form of your music or audio. When the combined wave form is played through the headphones speaker, the external noise is eliminated or canceled out and just the desired audio remains. That’s the basic principle.
Turning Waves into Compressions and Rarefactions
There’s a lot of intricate engineering that underpins active noise cancellation in order to better understand the engineering. It’s easier to visualize sound waves, not as these sinus soil patterns, but rather as a set of traveling high pressure zones known as compressions and low pressure zones known as rarefactions.
The Example of Removing the Noise from Traffic
Let’s say you live or work next to a highway, all the cars and trucks that zoom by generate a sound with a wave form, such as this, which is really just a sequence of traveling high pressure and low pressure zones, these compressions and rare factions move through the air. And when they hit your eardrum, you hear the sounds of the highway in order to produce an anti-sound wave for the highway’s noise.
A sound wave must be generated. That’s equal and opposite by that. We mean that for every high pressure zone from the noise, a low pressure zone needs to be generated. And for every low pressure zone from the noise, a high pressure zone needs to be generated the noise and anti-noise meet. And when these low pressure zones and high pressure zones meet or vice versa, they average out in that area. Thereby eliminating the sounds from the highway.
Issues with Noise Cancellation
There are a few engineering challenges with this solution. First the headphones or earbuds themselves provide some passive noise insulation. And therefore we need two microphones. One microphone is used on the outside to measure the noise itself. And the second microphone is used on the inside of the headphones to measure the percentage of noise that’s getting through the sound insulating properties of the headphones and into your ears.
The second challenge is that it’s rather difficult to perfectly time the anti-sound wave with the external noise. The noise from the highway has hundreds of compressions and refractions every single second. So if the anti-sound wave is off by a few milliseconds, then the noise cancellation won’t work properly.
Therefore, a high powered digital processor is used to measure and calculate the perfect anti sound wave. While simultaneously the interior microphone is monitoring. Whether the active noise cancellation is in fact working properly note that active noise cancellation is more effective for low frequency, repetitive noises, because they have only a couple hundred peaks and troughs or wave lengths every second.
But high frequency noises have thousands of wavelengths per second. If there’s even the smallest inaccuracy in timing, the anti-sound wave with the high frequency noise, the resulting combination between the anti-sound wave and the high frequency noise will be ineffective.
The third challenge managed by the processor and circuitry is that the anti-sound wave form needs to be combined with the audio wave form that’s sent from your smart.
The audio plus the anti-sound acts just like different instruments in a song. And they combine to make a new sound, which is played through the single speaker when the combined audio plus anti sound wave form, and the noise from the environment mix the anti-sound component of the combined wave form and the noise from the environment cancel out and were left hearing just the desired.
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