The three noise reduction measures commonly used to reduce noise, namely, noise reduction at the sound source, noise reduction during transmission and noise reduction at the human ear, are all passive

The three noise reduction measures commonly used to reduce noise, namely, noise reduction at the sound source, noise reduction during transmission and noise reduction at the human ear, are all passive

The three noise reduction measures commonly used to reduce noise, namely, noise reduction at the sound source, noise reduction during transmission and noise reduction at the human ear, are all passive

There are two noise reduction methods for earphones: active noise reduction and passive noise reduction.