Noise pollution in modern cities has become a primary environmental pollution. Buildings and high-speed acoustic environmental problems have attracted more and more attention. The selection of appropriate materials for sound absorption and sound insulation (sound barrier materials) disposal of buildings is one of the more commonly used and basic technical methods in building noise control projects. However, because of the lack of knowledge about the methods of noise control, "sound absorption" and "sound insulation", as completely different concepts, are often confused. Glass wool and rock mineral wool have excellent sound absorption function but poor sound insulation function. In order to use the materials reasonably and improve the noise control effect of buildings, it is necessary to further know and clarify the two concepts of "sound absorption" and "sound insulation".
The difference between material sound absorption and material sound insulation is that the sound absorption of materials focuses on the size of the reflected sound energy on the side of the sound source, and the policy is to reduce the reflected sound energy. Data sound insulation focuses on the size of the transmitted sound energy on the other side of the incident sound source, and the guideline is to reduce the transmitted sound energy. The attenuation and absorption of incident sound energy by sound absorption materials is usually only a few tenths. Therefore, its sound absorption ability, that is, the sound absorption coefficient, can be indicated by a decimal; while sound insulation materials can attenuate the transmitted sound energy to 10-3 of the incident sound energy. ～10-4 or less, for the convenience of expression, its sound insulation capacity is indicated in decibels.
Regarding sound insulation materials, to weaken the transmitted sound energy and obstruct the transmission of sound, it cannot be as porous, loose and breathable as the sound absorption materials. On the contrary, its raw materials should be heavy and dense, such as PC boards, endurance boards, and sound barrier boards. , Steel plate and other materials. The demand for sound insulation materials is dense without pores or gaps; it has a larger weight. Because this kind of sound insulation material is dense, it is difficult to absorb and transmit sound energy and the reflection energy is strong, so its sound absorption function is poor, and the most important thing is the effective sound insulation.
In engineering, sound absorption treatment and sound insulation treatment have different treatment policies and focus. The treatment policy of sound absorption treatment is to weaken the repeated reflection of sound in the room, that is, to weaken the indoor reverberation sound and shorten the reverberation sound. The moment is the reverberation moment; in the case of successive noises, this attenuation is manifested as a decrease in the indoor noise level, which is for the sound source and sound absorption materials in the same construction space. The sound absorption material also absorbs the sound from adjacent rooms, which is equivalent to improving the sound insulation of the enclosure layout.
It can be seen that the effect of using sound insulation materials or sound insulation layout to block noise is much higher than that of using sound absorption materials. This shows that when the noise source in a room can be separated, the sound insulation method should be selected first; when the sound source cannot be separated and the indoor noise needs to be reduced, the sound absorption method should be selected.
But the unique role of sound absorption materials is more on the ability to shorten and adjust the indoor reverberation time, which cannot be replaced by any other materials. Because the volume of the room is directly proportional to the reverberation time, the reverberation time of a large building space is long, and then affects the indoor listening conditions. At this moment, it is often inseparable from the sound absorption material to adjust the reverberation time. For large halls such as movie theaters, auditoriums, concert halls, etc., according to their different listening needs, appropriate sound absorption materials can be selected, and the reverberation time can be adjusted according to the body shape to achieve the needs of clear and full listening. From this point of view, the sound absorption material shows its unique importance, so it is usually used in KTV and other indoors. Outdoors such as high-speed sound barriers, railway sound barriers, highway sound barriers, high-speed sound barriers, etc. When choosing sound insulation, the more commonly used new sound insulation material is PC endurance board. The sound insulation effect of pc endurance board is obvious, and it has better sound insulation than glass and acrylic board of the same thickness. Under the same thickness, the sound insulation of endurance board is 5-9DB higher than that of glass. Internationally, it is the preferred material for highway noise barriers.