What is sound-absorbing material

Most of them are loose and porous materials, such as slag wool, blankets, etc., and their sound absorption mechanism is that sound waves go deep into the pores of the material. And the pores are mostly open holes that communicate with each other internally, which are subjected to friction and viscous resistance of air molecules, as well as mechanical vibration of fine fibers, so that sound energy is converted into heat energy.

Types of sound-absorbing materials

Sound-absorbing materials are generally divided into three types: fiber type, foam type, and particle type.

Common sound-absorbing panels on the market include wooden sound-absorbing panels, fabric sound-absorbing panels, foam sound-absorbing panels, polyester fiber sound-absorbing panels, wood wool sound-absorbing panels, etc.

Fiber-type materials are divided into two types: organic fibers and inorganic fibers. Organic fibers are mainly made of sound insulation cotton, slag wool, glass wool, rock wool, etc. Among them, glass wool can be used to make glass mat. Sound insulation cotton is the most commonly used sound-absorbing material, and its advantages are: non-combustible, heat-resistant, corrosion-resistant, etc. If the sound insulation cotton is treated with silicone oil, it can also play a role in fire prevention and moisture resistance.

Foam-type sound-absorbing materials have the advantages of small bulk density, thermal conductivity, and soft texture. If they are insufficient, they are easy to age and have poor fire resistance.

The granular material can prevent moisture, heat preservation, corrosion resistance and so on.

The principle of sound-absorbing materials

Sound-absorbing material (sound-absorbing material): Any material can absorb sound, but the degree of absorption is very different. Generally, materials with an average sound absorption coefficient of more than 0.2 for the above six frequencies are listed as sound-absorbing materials. Sound-absorbing materials Most of the sound-absorbing materials are loose and porous materials, such as slag wool and blankets. Its sound absorption mechanism is that sound waves go deep into the pores of the material, and the pores are mostly open holes that communicate with each other internally. They are subjected to friction and viscous resistance of air molecules, and mechanical vibration of fine fibers, thereby converting sound energy into heat energy. The sound absorption coefficient of this kind of porous sound-absorbing material generally increases gradually from low frequency to high frequency, so the sound absorption effect on high frequency and intermediate frequency is better. The working principle of sound-absorbing materials: sound originates from the vibration of objects, which causes the vibration of adjacent air to form sound waves, and spreads around in the air medium. Sound-absorbing material: When the sound is transmitted to the surface of the component material, part of the sound energy is reflected, part of it penetrates the material, and part of it is due to the vibration of the component material or the friction with the surrounding medium when the sound propagates in it. The sound energy is converted into heat energy, and the sound energy is lost, that is to say, the sound is absorbed by the material. Sound absorption coefficient: The sound absorption performance of the material is expressed by the sound absorption coefficient α. Α is the sum of the loss coefficient Eab/E0 and the penetration coefficient Ethr/E0. The sound absorption performance of the material is not only related to the structure, thickness and surface characteristics of the material itself, but also related to the incident direction and frequency of the sound.

Application of sound-absorbing materials in construction

(1) Control the reverberation time of the sound quality of halls, such as concert halls, theaters, recording studios, studios, audition rooms, conference rooms, multi-functional halls, gymnasiums, auditoriums, etc. Generally, the best reverberation time is achieved by selecting and arranging suitable sound-absorbing materials.
(2) For some public transportation buildings, such as the waiting hall of the airport, the waiting room of the station, and the waiting room of the wharf. Because it is necessary to continuously broadcast information such as the departure, arrival or delay time of planes and trains and ships. Sound-absorbing materials such as foam can be properly arranged on the ceiling and walls. On the one hand, it can improve the clarity of broadcast information; on the other hand, it can also reduce the noise of passengers and make the environment quieter.
(3) Eliminate sound quality defects such as echo and sound focus in the hall. When the sound path difference between the direct sound and the reflected sound reaches 17m, the time difference between the two sounds reaches 50ms, and the human ear can hear the echo. In some longer halls, the reflected sound from the back wall is likely to echo in the seating area near the entrance of the platform. It can be eliminated by arranging strong sound-absorbing board materials on the rear wall. For example, the arc-shaped back wall and domed roof of the building will bring focus to the hall. If you want to keep the original trapezoid shape in the room, you can use the method of arranging strong sound-absorbing materials on these inner surfaces to eliminate the focus on the hall.
(4) Improve the sound insulation of light and thin board walls. Such as gypsum board, silicon-calcium board, FC board, TK board and fireproof magnesium cement board and other light and thin board walls. Filling the interlayer with porous sound-absorbing materials such as glass wool, rock wool and mineral wool can significantly improve the sound insulation effect of this type of board wall.