According to the sound absorption characteristics, the sound absorbing materials are divided into two categories: medium and high frequency sound absorbing materials and low frequency sound absorbing materials; according to the appearance and structural characteristics of sound absorbing materials, they can be classified into porous sound absorbing materials, resonant sound absorbing materials and the like. Porous sound absorbing materials are mainly used for medium and high frequency sounds, and resonant sound absorbing materials are used for medium and low frequency sounds.
The sound absorbing material has two important acoustic parameters, namely the sound absorption coefficient α and the noise reduction coefficient NRC. The sound absorption coefficient α refers to the ratio of absorbed acoustic energy to incident acoustic energy of an acoustic material. NRC is a sound absorption performance standard established by the American Society for Testing and Materials (ASTM), which represents the arithmetic mean of the sound absorption coefficient of a material at frequencies of 125 Hz, 250 Hz, 500 Hz, 1000 Hz, 2000 Hz, etc., rounded to 0.05. Under normal conditions, a material with a noise reduction coefficient NRC of less than 0.2 belongs to a reflective material, and a material with an NRC greater than 0.4 is a sound absorbing material.
Porous sound absorbing materials, as the name implies, are acoustic materials with a large number of tiny voids and holes connected inside and outside. They have good sound absorption characteristics for medium and high sounds, and have good application in the acoustic processing of audiovisual space in home theater design. The most widely used sound absorbing material in processing.
The main factors affecting and controlling the sound absorption characteristics of porous sound absorbing materials are the porosity, structure and air flow resistance of the material. Among them, the air flow resistance is the most important. When the material thickness is not large, the air flow resistance is larger, the air penetration is smaller, and the sound absorption performance is lower. Therefore, the porous sound absorbing material must have the following conditions: 1. There should be a large number of micropores or gaps inside the material, and the pores should be as small as possible and evenly distributed; 2. The micropores inside the material must face outward and must pass through the material. The surface allows sound waves to enter the interior of the material more easily from the surface of the material. 3. The micropores inside the material are interconnected rather than closed. Welcome to the home theater network shopping guide network!
The resonant sound absorbing material is mainly for low frequency sound of 250 Hz or less. The basic principle is that vibration is generated by the object in the closed cavity under the excitation of the sound wave, and the vibration object transforms part of the vibration energy into friction due to internal friction and air friction. Consumption by heat. In this configuration, it is possible to consume sound energy and produce a sound absorbing effect. The vibration of the object is the strongest, the amplitude and speed will reach the maximum value, and the more energy loss is caused, the more the sound absorption effect is.
Porous sound absorbing materials and resonant sound absorbing materials are the most used acoustic materials for home theater design audiovisual space sound absorption processing. When the home theater design audiovisual space reverberation time is too long, you can use sound absorbing materials on the wall surface of the room to increase the sound absorption of the audiovisual space to reduce the reverberation time. And pay attention to the use of different sound absorbing materials for the sound of different frequency bands, targeted control.
Dog Fence Wire,Invisible Fence Wire,Electric Dog Fence Wire,Invisible Dog Fence Wire
Elite-tek Electronics Ltd , https://www.aetertek.ca