Usually when we encounter a noise problem in our life the first thing we do is seek to block it out.
This is called passive noise reduction it involves insulating a room or your ears against sound and is the typical method employed for most soundproofing projects.
Active Noise Cancellation is very different. Instead of passively doing nothing other than blocking the sound Active Noise Cancellation is a method in which sound is actively created to cancel out any problem noise.
What Is Active Noise Cancellation?
Active Noice Cancellation (ANC) uses sound to minimise other sounds, you may be thinking that ANC is just a technical term for white noise but actually it is very different as active noise is designed to counteract problem noise causing both noises to effectively cancel each other out so you don’t hear anything.
Active Noise Cancellation is a technology which is used in some high-end headphones. It is also commonly known as Active Noise Reduction (ANR) and Active Noise Control (ANC) technology.
How Does Active Noise Reduction Work?
Headphones which use active noice cancellation utilise a small microphone on the outside of the headphone piece to listen to the ambient noise in the background.
It will pick up problem background noises such as traffic, music, people talking and relay them back to the headphones.
The headphones contains a special noice cancelling circuit which is capable of producing the opposite soundwaves to the sounds that the microphone picks up.
This means that the active sound cancels out the background noise so you hear nothing!
The video below does a good job of explaining how it works in headphones:
In more technical terms noise consists of alternating waves of compression and rarefaction (basically decompression or the opposite of compression).
Active noise cancellation works by mirroring the exact compression and rarefactions of the sound waves with exactly the same amplitude (volume), the difference between the original sound and the ANC sound is that the ANC soundwaves are inverted. This process causes the soundwaves to combine in a process called destructive interference which forms a new combined neutral soundwave.
It goes without saying that this sort of technology requires batteries, so unfortunately it is not scalable to use for reducing noise in a home as you would require a lot of power (read our article on home noise cancelling systems for more information on this), however it is well suited for use in cars or headphones such as the ones below:
What Is Active Noice Control Technology Useful For?
The world seems to be getting busier and noisier with every passing day, increasingly it is becoming more and more difficult to find peace and quiet.
Technology makes out homes noisier than ever, busy trains and buses, as well as loud roads and traffic noises, make our commutes noisier than ever and there is no peace to be found in most workplaces.
Finding moments of quiet away from the noise is important for our general health and well being. Reducing the amount of sound (particularly loud sound) in your life will help to improve your health in a number of ways:
- It will minimise the danger of hearing loss.
- Reduce blood pressure.
- Reduce heart rate.
Over time these issues can lead to serious health complications. Taking steps to ensure that your car is soundproofed your home is well insulated against noise and your working life isn’t too noisy can be time consuming and expensive.
Also Read: 14 Of The Best Car Sound Deadening Materials
Active Noice Cancelling headphones aren’t cheap (they are cheap compared to the overall cost of some soundproofing projects) but they are a great solution which will completely neutralise background noise on your commute, in your home or wherever you are.
Using active noise cancelling headphones will help protect your ears and will minimise stress in your life so they could be well worth considering before you embark on a costly and time consuming DIY soundproofing project.
The History of Active Noice Cancelling Technology
Active Noise Reduction technology is often thought of as being a very modern invention as the general public have only recently become widely aware of it with the growth in popularity of ANC headphones, however ANC technology has been around in one form or another for over 80 years.
Way back in 1936 Mr Paul Lueg from the U.S.A was granted a patent for a noise controlling system which worked by inverting the polarity of sounds and playing it back to cancel out any uneccessary background sounds.
14 years later in 1950 a Mr Lawrence Fogel was granted another ANC patent which was designed to cancel out background noise in the cockpits of helicopters and planes.
7 years late in 1957 Mr Willard Meeker created a working model of how active noise control could be used on headphones (as they are today).
However it wasn’t until 1986 that the first working prototype of active noise cancelling headsets were actually made by Bose.
From here ANC technology begun to develop rapidly and in 1992 the Nissan Bluebird (pictured below) was the first car to use ANC technology.
Though it was another 20 years until active noice reduction technology was more widely adopted in automobiles.
By 2012 the benefits of noise reduction technology were clear and the many companies had developed the ability to implement it effectively, now many new car models use it and many top end headphones are sold with it as a key feature.