Generally speaking, it takes 20-50 milliseconds to recognize the sound. The distance between the sound source and the two ears is 1 second, and the propagation time is 0.029 milliseconds. When the distance is doubled, the sound pressure level is reduced by 6dB. ).

The 1V voltage output generated at 1μbar input sound pressure is defined as 0dB. If the sound source is far away from the microphone, a high sensitivity microphone is required; this way, the sound of the sound source can be clearly and correctly picked up. If the sound source is close to the microphone, use a low sensitivity microphone, which has a balance point.