This harsh voice is called "howling", or "feedback gain". The reason for this phenomenon is as follows:

① The speaker has a peak on a certain frequency in the sound characteristics. The peak values in these three red circles are the root cause of howling. What happens when there is a peak? The microphone will continue to receive this peak, and the audio will continue to play this peak. Many times a second, the peak will be enlarged infinitely until the device is damaged.

② The input signal is too loud, causing the disappointment of the release of the release. In the final analysis, it is the first reason. Okay, there are editors who tell you how to solve this problem.

① Use good microphone and audio.

Why do you say that? Because good audio and microphones are very smooth in sound characteristics, this smoothness does not mean that his curve is straight. Instead, the waveform is too smooth. In this way, there will not be a peak of a narrow -frequency band if you do not produce tampering and filtering, and how it will rarely occur.

② Try not to be too close to the sound or not to point the sound. In this way, even some frequency screaming points can be effectively avoided.