Noise-canceling headphones adopt active noise control, which is different from the passive sound insulation of ordinary headphones. Its principle is:

1. First, the signal microphone placed in the earphone detects the low-frequency noise (100 ~ 1000Hz) in the environment that the ear can hear (currently it can reach 3000Hz)

2. Then transmit the noise signal to the control circuit, and the control circuit performs real-time calculation

3. The Hi-Fi speaker emits a sound wave with the opposite phase and the same amplitude as the noise to cancel the noise, so the noise disappears and cannot be heard

Active noise-canceling headphones are expensive, but they generally work well and are comfortable to wear. Requires independent battery power supply, most passive noise-canceling headphones can be used without power consumption (nor active noise-canceling)