1. Reduction of ground grazing absorption
The so-called sonic absorption of sound is the phenomenon that the sound energy is absorbed by rough surface when the sound wave propagates along a rough plane. The large amount of grazing absorption will increase the attenuation of sound waves in propagation, resulting in the fact that sound can not travel far and seriously affect the effect of sound reinforcement. According to the outdoor acoustics theory, when the sound and the ground angle of the sound source are less than 30 degrees, if the ground is soft, such as grassland and soil, the sound will be absorbed most of the ground, and the sound energy can not be sent to the ideal place. This absorption is actually grazing absorption, so it is necessary to pay extra attention to the outdoor arrangement of the sound box. The best way is to hang or support the sound box, so that the sound line of the sound box and the ground angle are more than 30 degrees, so that the sound emitted by the sound box can be fully sent to the audience.
Two. Pay attention to the influence of ambient sound environment
In outdoor sound expansion, the absolute open space is more common. Most sound reinforcement sites have such objects that may affect the sound reproduction, such as all kinds of buildings, billboards, and field fences that affect sound reproduction, so the acoustics should carefully observe the surrounding acoustic environment and take full examination when they enter the scene. Consider all kinds of reflection problems in order to make better use and use of acoustic reflection to reduce the possible adverse consequences of acoustic reflection.
Tall buildings can be seen as a huge sound reflection interface. Under outdoor conditions, the sound emitted by the sound box is hit by the building, and the reflection of the building usually produces only one reflection, and more than two times are reflected. When a reflection is heard by the audience, it will give people a similar feeling of delay or single echo. As you know, too much of a reflection in a sound can not only cause a sound image confusion, but also can destroy the clarity of the sound as a result of the sound of the sound.
In addition, the sound is transmitted to the sound which is being picked up through reflection, and it can also cause voice feedback, resulting in acoustic feedback whistle. We often find outdoor sound expansion system most likely to occur at the lowest frequency feedback, which is because the bass have good diffraction characteristics and larger point of angle, in the air decline and so on.
