Noise cancelling Headphone is a type of headset that uses some method to reduce noise. There are two types of noise reduction headphones: active noise reduction headphones and passive noise reduction headphones.
Noise-reducing headphones, using active noise control, are different from the passive sound insulation of general headphones. The principle is:
1. Detect low-frequency noise (100 to 1000Hz) in the environment that can be heard by the ear from a microphone placed in the earphone
2. The noise signal is then transmitted to the control circuit, and the control circuit performs real-time operation
3. Play sound waves with the same phase and amplitude as the noise from the Hi-Fi speaker to counteract the noise
4. Noise disappears after superimposition