Noise cancellation is quickly becoming a common feature for consumer headphones, office spaces, automobiles and even as sleeping aids. What exactly is noise cancellation and how does it work?
History
Prior to noise cancellation technology, engineers primarily relied on passive noise control practices with techniques like acoustical soundproofing, vacuum principals, and use of heavy bulky materials to physically block sound in listening environments. Although this method works, it isn’t very comfortable when applied to wearables and isn’t safe when you need to hear things like sirens while in a moving vehicle.
Active Noise Control
Today’s products offer noise cancellation using Active Noise Control practices. Utilizing ANC provides a much better listening environment and can provide clear detail at minimal volume levels. This is achieved using microphones to capture ambient noise outside of the listening environment. The processor then analyzes the waveform, flips it 180 degrees out of phase, and plays the sound back to you in your environment all within milliseconds. The delay is not enough for the human brain to understand so you will rarely realize it is happening. This process utilizes the phenomenon known as phase cancellation which effectively wipes out 100% of audio when 2 sounds of the exact same frequency are played out of phase with each other.
The phase cancellation method works pretty well for the lower end of the audio spectrum and things such as road and tire noise in a vehicle. Higher frequency noises which have a shorter wave length still depend on the use of soundproofing. Phase cancellation is still possible at higher frequencies but the amount of equipment required to make it work in a pair of headphones is just not feasible.
We’re not there yet
Noise-cancellation technology is still developing so we will see it used more and more in our everyday products. Current drawbacks are power requirements needed for the analyzing and processing of the ambient audio. This typically means a 9volt battery is needed for headphones. Some users also experience a high frequency hiss which comes from the noise cancellation frequency. Audible noise can commonly be attributed to the quality of electronics used in the noise cancelling product.
As technology continues to improve and chip-sets get smaller, we will see a growth in this segment of the headphone market. Eventually, Noise cancelling technology will be standard in headphones, vehicles, and office buildings.