The principle of noise-cancelling headphones is mainly divided into three steps
The principle of noise{{0}}cancelling headphones is to use the interference of waves. If two identical sound waves hit your ears, if the crest meets the crest and the trough meets the trough, you will hear four times the volume, because the energy of the sound is proportional to the square of the amplitude of the sound wave, and the amplitude changes. Doubled, the energy is quadrupled. If the peak and the trough meet, the positive and negative offsets, the amplitude of the sound is 0, you will feel very quiet, because the sound is completely canceled. Noise-cancelling headphones not only have speakers, but also a microphone, which is designed to capture ambient noise.
The principle of physical noise reduction: the use of external hard materials and internal filling materials to block the sound from entering the human ear can play a certain role in isolating and absorbing noise.
This physical noise reduction method is simple, common and easy to implement. It's just that the physical noise reduction has obvious shielding effect on high-frequency noise, but it seems a little helpless for medium and low-frequency noise. In the noise range of 800Hz or lower, physical noise reduction does not work well. On the other hand, physical noise-cancelling headphones can block the sound of the human voice while isolating the external environmental noise. There is a certain danger in using passive earplugs to reduce noise.
The principle of active noise canceling headphones is mainly divided into three steps:
Use highly sensitive microphones as sensors to collect and analyze external environmental noise (mainly high-frequency noise);
Calculate the wave frequency of the collected noise sound waves in real time, generate reverse sound waves, and cancel each other after combining the two sound waves with a 180-degree angle;
When the sound enters the human ear, the noise cancellation effect is achieved due to the mutual cancellation of the noise and the reverse sound waves.
