The system is based on microphones that “listen” to the sounds outside and inside of the earphone, an ANC chipset inverting the soundwaves and a speaker inside the earphone cancelling the outside sound by the neutralising soundwaves. A bit like taking +2 outside and adding -2 inside to make zero.

How does Active Noise Cancellation work?

The technology, known as active noise-cancellation (ANC), works by using microphones to pick up low-frequency noise and neutralise it before it reaches the ear. The headset generates a sound that's phase-inverted by 180 degrees to the unwanted noise, resulting in the two sounds cancelling each other out.

Is ANC bad for your ears?

Overall, noise cancellation in headphones doesn't affect your hearing negatively. You may hear a slight hissing sound when you the ANC is turned on, but that's about it. However, for some people this can be irritating and even result in dizziness. ... Keep in mind, that this hissing sound does not damage hearing.