Sound absorption and noise reduction refers to the indoor use of sound absorption materials or suspended space absorbers to absorb sound energy to reduce noise, which is an important measure of building environmental noise control technology.With the development of sound-absorbing materials and their structural forms, sound absorption and noise reduction technology is increasingly widely used in industrial and civil building noise control.[1]
Sound absorption and noise reductionSound absorbing materialOr sound absorption structure to absorb sound energy, so as to reduce the noise intensity.
Figure 1
Sound absorption material noise reduction is to absorb part of sound waves by using the characteristics of soft and porous sound absorption materials. When sound waves enterporous material After the pores of, it can cause the air in the pores and the fine fibers of the materials to vibrate. Due to the friction resistance between the air and the hole wall, the viscous resistance of the air, and the heat conduction, a considerable part of the sound energy will be converted into heat energy and dissipated, thus playing the role of sound absorption and noise reduction.
The sound absorption principle can be shown in Figure 1.When sound waves incident on the surface of barriers (such as walls, ceilings, floors, sound absorbing materials, etc.), part of the sound energy is reflected, part of the sound energy is absorbed, and the rest of the sound energy passes through the barriers and into the adjacent room, so as to achieve the purpose of noise reduction due to the reduction of sound energy.We often compare the sound energy E absorbed by a surface with the sound energy incident on the surface
The ratio is called sound absorption coefficient α:
Where:
——Incident acoustic energy;
E -- Absorbed sound energy.
The larger the sound absorption coefficient a is, the better the absorption effect of materials and structures is. The α value of most sound absorption materials and structures is between 0.2 and 1.The sound absorption coefficient is related to the physical properties of materials, the frequency of sound waves and the incident angle of sound waves.[2]
Design steps
Announce
edit
The design steps of sound absorption and noise reduction are:
① Measure the original indoor noise level and noise spectrum characteristics, determine the allowable noise value at a certain distance point of the high sound source, and then obtain the required sound absorption and noise reduction amount;
③ Calculate the sound absorption coefficient and room constant after sound absorption and noise reduction treatment;
④ Select appropriate sound absorption materials or structures, and make indoor sound absorption design to reach the required average sound absorption coefficient.
When selecting materials in the sound absorption and noise reduction project, in addition to the noise reduction effect, attention should also be paid to the process requirements of fire prevention, moisture-proof, corrosion prevention, and communication, lighting, lighting, decoration and other requirements[1]
Applicable conditions
Announce
edit
Sound absorption and noise reduction is an effective method to control noise.It can not only be used to improve the acoustic environment (such as large offices, workshops, workshops and residential buildings), but also to reduce the noise of sound sources (such as in relatively small enclosures).However, this method has some limitations, and the main scope of application is as follows:
(1) When the room volume is less than 3000m ³, the noise reduction effect is good;
(2) The indoor surface is mostly hard reflective surface, and there is no object with strong sound absorption performance in the room, where reverberation is dominant;
