Modern urban noise pollution has become a primary environmental pollution, and buildings and high-speed acoustic environmental problems are attracting more and more attention. It is one of the common and basic technical methods in building noise control engineering to select appropriate data for sound absorption and insulation (noise barrier data) disposal of buildings. However, due to the lack of knowledge of noise control methods, "sound absorption" and "sound insulation" are often mixed as different concepts. Glass wool and rock mineral wool have excellent sound absorption function but poor sound insulation function. In order to reasonably use data and improve the noise control effect of buildings, it is necessary to further understand and clarify the concepts of "sound absorption" and "sound insulation".
The difference between data sound absorption and data sound insulation is that the sound absorption of data 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. The data sound insulation focuses on the size of the transmitted sound energy on the other side of the incident sound source, and the policy is to reduce the transmitted sound energy. The attenuation and absorption of the sound absorption data to the incident sound energy is usually only a few tenths, so the sound absorption ability, namely, the sound absorption coefficient, can be expressed by decimals; The sound insulation data can make the transmitted sound energy attenuate to 10-3~10-4 or less of the incident sound energy. For the convenience of expression, the sound insulation is measured in decibels.
As for sound insulation materials, to weaken the transmitted sound energy and block the transmission of sound, they should not be as porous, loose and breathable as sound absorption materials. On the contrary, their raw materials should be heavy and dense, such as PC boards, endurance boards, sound screen baffles, steel plates, etc. The demand for raw materials of sound insulation data is dense without pores or gaps; It has a large component. Because this kind of sound insulation data is dense, it is difficult to absorb and transmit sound energy, but the reflection energy is strong, so its sound absorption function is poor, and the most important thing is useful sound insulation.
In engineering, the principles and concerns of sound absorption disposal and sound insulation disposal are different. The principles of sound absorption disposal are to weaken the repeated reflection of sound in the room, that is, to weaken the reverberation in the room, and to shorten the continuous time of reverberation, that is, the reverberation time; In the case of continuous noise, this weakening is shown as the decline of indoor noise level, which is for the sound source and absorption data are located in the same building space. For the sound transmitted from adjacent rooms, the sound absorption data also plays an absorption role, and then is equivalent to the sound insulation amount of the improved enclosure layout.
It can be seen that the noise reduction effect of sound insulation data or sound insulation layout is much higher than that of sound absorption data. This shows that when the noise sources in a room can be separated, the sound insulation method should be selected first; When the sound source cannot be isolated and the indoor noise needs to be reduced, the sound absorption method shall be selected.
However, the function of sound absorption data is more reflected in the ability to shorten and adjust the indoor reverberation time, which can not be replaced by any other data. Because the volume of the room is in direct proportion to the reverberation time, the reverberation time of the large building space is long, and then affects the indoor hearing conditions. At this moment, it is often inseparable from the sound absorption data to regulate the reverberation time. For large halls such as cinemas, auditoriums and concert halls, appropriate sound absorption data can be selected according to their different listening needs, and reverberation time can be adjusted according to their shape to meet the needs of different one-sided feelings such as clear and full listening. From this point of view, sound absorption data shows its importance. Therefore, it is usually used in KTV and other indoor areas. For outdoor areas, such as high-speed sound barrier, railway sound barrier, highway sound barrier, high-speed sound barrier, etc., sound insulation measures are used. The more commonly used new type of sound insulation data is PC endurance board. PC endurance board has obvious sound insulation effect, which is better than glass and sub stress board with the same thickness. Under the same thickness, the sound insulation of endurance board is 5-9DB higher than glass. Internationally, it is the preferred material for highway sound barrier.
