2021-12-13 14:35:03, 修改于2021-12-13 14:42:24
The three noise reduction measures commonly used to reduce noise, namely noise reduction at the sound source, noise reduction during propagation, and noise reduction at the human ear, are all passive.Active Noise Cancelling Headphones，
In order to actively eliminate noise, people invented the "active noise reduction" technology. Its principle is: all sounds are composed of a certain frequency spectrum. If you can find a sound whose frequency spectrum is exactly the same as the noise to be eliminated, but the phase is exactly opposite (a difference of 180°), the noise can be completely cancelled out. .
The key is how to get the sound that cancels the noise. The actual method used is to start with the noise source itself and try to reverse the phase of the original noise through the electronic circuit. From this point of view, the technology of active noise reduction is actually "fighting poison with poison."
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