Active noise cancelling headphones are a special type of headphones that use active noise control to suppress unwanted ambient sounds. This is different from passive headphones, which use techniques such as soundproofing to reduce ambient sounds. Active noise cancelling headphones use a microphone to capture targeted ambient sounds, and a small amplifier generates sound waves that are exactly out of phase with the undesired sounds. When the sound pressure of the noise wave is high, the cancelling wave is low (and vice versa). The opposite sound waves collide and are eliminated or "cancelled" (destructive interference) .
Active noise cancelling headphones can be processed through the ANC chipset using either feedforward or feedback technology. Feedforward ANC is the simplest type of active noise cancellation, where the noise-capturing microphones are placed on the outside of the headphones. Feedback ANC is less effective than feedforward ANC, as it uses microphones placed inside the ear cup to pick up unpredictable noises that may actually get amplified and not canceled out.
It is worth noting that active noise cancelling headphones do not cancel out all noises equally. They are generally more effective on lower frequencies of sound, such as the hum of a jet engine or an air conditioner, and less successful with human voices and other higher frequencies.
Overall, active noise cancelling headphones are a great option for those who want to listen to music or other audio in noisy environments. They can be more expensive than regular headphones, and require power, usually supplied by a USB port or a battery that must occasionally be replaced or recharged.
