Noise cancelling technology:
There are two types of ways to achieve noise cancellation, passive noise cancellation and active noise cancellation. Active noise cancellation is to use an extra microphone which emits high pitch frequency to counter the low frequency external sound. Noise cancelling headphones usually use active noise control (ANC), sounds travel through the air or through liquids in the form of waves, and each of those waves has a particular shape. Noise cancelling technologies first rely on small microphones that identify the sounds in a given environment. A digital signal processor determines what sound wave is necessary to cancel the unwanted sound wave and then it generates that sound and amplifies it through speakers or headphones. So basically two different frequency sound waves cancel each other out, thereby bringing the listener closer to silence.
So what’s the point of using ANC?
The main aim for ANC is to eliminate sound (noise) from a single source, prevent listeners from turning up the volume to a harmful level just to cover the noise, as cities nowadays are filled with hundreds of different unwanted noise. Headphone users often got interrupted by the noise. In a result of that users cannot fully enjoy their music. So, the purpose of this technology is to cancel or at least keep to the minimal of the unwanted sounds, in order to provide quietness for headphone users who live in busy, noisy area.