Throughout the national organization of departments meeting system routine debugging and holding meetings, the quality of sound recovery has made significant progress, but there are still problems in individual provinces and cities, mainly manifested as large noise, distortion, level non-standard, frequency response uneven, sound proportion imbalance, improper reverberation delay and other problems.

1. Loud noise. It affects the clarity, gentleness and brightness of the sound, and in severe cases can mask the sound of the venue.

① Background noise. Due to excessive gain, automatic gain control, impedance mismatch, etc., will present background noise.

② Microphone "flutter" sound. The microphone is the first link of the PA system, and the quality of its signal directly affects the effect of the whole conference, so it is reasonable to choose and set according to its characteristics and performance, the characteristics of sound source reproduction and the relative relationship between the sound sources. For speakers with strong broken sound, a microphone that prevents "flapping" should be used.

2, the distortion is large. It is related to the nonlinear distortion of equipment and human factors. It is characterized by hoarseness, breakage, sharpness and harshness of the voice, which will affect the clarity, gentleness, brightness, fullness and sense of scene of the voice. The causes of distortion are many, such as the flexible high of the microphone, the improper placement, the abnormal power supply of the microphone with the phantom power supply, the level adjustment of the mixer is too large, the adjustment of the balancer is inappropriate, and the impedance mismatch between the devices.

3, the level is not standard. Before debugging, the equipment such as the mixer and the balancer is not stopped, resulting in too high or too low signal level. In addition, the unbalanced line output is directly connected with the balanced line input to form a signal level drop.

4. Uneven frequency response. It is related to the frequency response index of the equipment and human factors, such as the direction of the microphone deviates from the sound source, too much attenuation of the medium frequency and low frequency, and the microphone transmission line is too long, which will affect the clarity, layer sense and fullness of the sound recovery.

5. Voice imbalance. If the sound proportion between the main control room, the main venue, and the sub-venue of the speech is out of whack, it will affect the balance of remote sound recovery in other sub-venues, and form the overall effect of the meeting.

6. Improper reverberation delay. Different meeting types and pickup environments have different requirements for reverberation and delay, so the parameters of reverberation and delay should be adjusted according to the acoustic characteristics.

①The size of the venue affects the time of reflection in the reverberation of the sound field and the auditory sense of time.

② Reverberation time reflects the process of sound absorption and reflection from the sound source. The reverberation time depends on the size of the venue. The larger the space, the larger the reverberation time. Some sound defects should be compensated and modified by audio processing equipment, but improper adjustment will backfire. If the reverberation time is too long, the sound will have a sense of "turbidity", so it is necessary to separate the practice and reasonably participate in the reverberation effect to strengthen the depth of the sound. The same goes for delayed handling.

③ The frequency characteristics of reverberation reflect the reverberation effect and sound quality of sound at different frequencies. To be familiar with the frequency characteristics of reverberation, adjust the proportion of direct sound and reflected sound picked up by the microphone to increase the realism and clarity of the sound.

④ Sound diffusion is a parameter that reflects the acoustic characteristics of the venue. It is necessary to set the microphone reasonably to compensate for the defects of the sound diffusion conditions of the venue, and to avoid the direction with trembling echo area and strong reflection.