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What is Active Noise Cancellation

What is Active Noise Cancellation and How Does it Work?

Having a noise cancellation headset helps you peacefully focus on your work, amidst chaos. How does this technology work? Find out here.
Omkar Phatak
Last Updated: Jan 11, 2019
One of the negative byproducts of technology is incoherent and unwanted noise, which is the nemesis of soulful silence. We can close our eyes, but there is no way of closing our ears and running away from noise.
Ear plugs do help, but there is no way you can really blank out all the noise from jarring your eardrums, or is there? With noise cancellation technology, there is hope, that you can actually blank out the chaotic sound waves hitting your eardrums.
Sound propagates through air as pressure waves, that cause alternate compressions and rarefactions in the air volume.
Each sound frequency is a wave of compressions and rarefactions of air, traveling in space. When these waves hit your eardrums, they make the ear bones vibrate. This generates electrical signals, that are sent to your brain, which you identify as sound.
Noise occurs through a superimposition of sound waves of different frequencies which sends you eardrums into a tizzy.
How Does it Work?
This technology is designed with the aim of neutralizing noise in real time. The 'active' epithet refers to the working of the technology in real time. The principle on which this technology is entirely based, is called destructive interference of waves.
When two waves of exactly same frequencies, but 180 degrees out of phase, superimpose on each other, they simply cancel each other out. When a compression wave meets a rarefaction wave of exactly same amplitude, they neutralize each other. This is what is called destructive interference.
So this technology creates sound waves that are exactly matching with surrounding sound, but which are out of phase to cancel out the surrounding sound. Canceling out a single sound frequency this way is simple, but to cancel out noise, one must create out of phase sound waves, of all the mixing individual frequencies, which is not yet completely possible.
An intelligent noise cancellation system will be able to recognize the individual frequencies that are mixed up to make noise and will create sound waves that cancel them out through destructive interference.
However, there is no such perfect system yet created, though active noise canceling headphones and other devices are now available, which can phase out some of surrounding noise, in any environment.
There are many applications of this technology. Headphones based on this technology can help air traffic employees, who work in high decibel environment, as well as workers who deal with high noise pollution environment like metal work industries and construction.
It can save a lot of people from long term ear damage and other ear problems, that prolonged exposure to noise can cause. With each advance in technology, we are increasingly learning to master the influences of external environment upon us and this technology is one more step in that direction.
Thus, in this technology lies the hope that people can effectively protect their ears from the onslaught of noise. With elaborately designed noise cancellation software, even complex noise may be completely eliminated in the future. So we can look forward to a world where we can rescue silence back again, from the clutches of all pervading noise.