However, due to lack of understanding means noise control, "absorption" and "noise" as a completely different concept, they are often confused. Glass wool, rock cotton has good absorption properties for a class but the poor performance of insulation materials are mistakenly called "sound material", the early years of some plant fiber as raw material made of sound-absorbing board is named "sound board" and to solve the problem of sound insulation of buildings ....... To the rational use of materials to improve the building noise control effect, "absorption" and "noise" of these two concepts have a better understanding and a clear need. The difference between sound absorption and sound insulation material that looks at the size of the sound-absorbing material source side of the reflected sound energy, the goal is the reflected sound energy to be small. Insulation material focusing on the other side of the incident sound source acoustic energy transmission size, the goal is the transmission of sound energy to be small. Sound-absorbing material to absorb incident sound energy attenuation, usually only a few tenths, so its sound absorption capability that is the absorption coefficient can be expressed as a decimal; and sound insulation material enables the transmission of sound energy to incident sound energy attenuation of 10-3 to 10-4 or less, for the convenience of expression, its sound insulation expressed in dB measurement methods. Differences between these two materials in the material is sound-absorbing material on the incident sound reflected little energy, which means the sound can easily enter and pass through this material; you can imagine, this material should be porous material, porosity and breathable, this is a typical porous sound-absorbing material, it is used in the process is usually fibrous, granular or foamed material to form a porous structure; its structure is characterized by: having a large number of materials, each through- From table to inside the pores, that has a certain permeability. When sound waves incident on the surface of the porous material, the pores of the air caused by vibration due to viscous friction and air resistance and heat conduction, the considerable part of the sound energy into heat energy, which in turn has sound-absorbing effect. For insulation material, sound transmission can be reduced to block sound transmission, it will not be as porous as sound-absorbing material, loose, breathable, on the contrary it should be heavy and dense materials, such as steel, lead, and so on a brick wall class materials. Insulation material is dense material requirements without pores or slits; greater weight. Since this type of insulation material dense, difficult to absorb, and through sound energy and reflected energy is strong, so its poor absorption properties. In engineering, the target and focus of the acoustic treatment and acoustic treatment to solve different acoustic treatment goal is to weaken the resolve repeatedly reflected sound in the room, that weaken reverberant chamber, reverberant shorten the duration of That reverberation time; in the case of continuous noise, which weakened performance in order to reduce indoor noise level, this point is the sound source and sound-absorbing material with the Department in terms of a building space. The adjacent room pass over the sound, sound-absorbing material also plays absorption, thus equivalent to increases in sound insulation envelope structure. Acoustic treatment, aimed at the isolation of noise from the sound source room adjacent room to spread to the adjacent room from interference noise. It can be seen, the use of acoustic insulation materials or the effect of construction noise isolation than the use of noise reduction effect of sound-absorbing material is much higher. This shows that, when the noise source in a room can be separated, you should first use of sound insulation measures; if the sound source can not be separated when they need to reduce interior noise sound absorbing measures. But the unique role of sound-absorbing material more marked shortening now, the ability to adjust the indoor reverberation time, which no other material can not be replaced. Since the volume of the room and the reverberation time is proportional to the relationship, a large volume of building space reverberation time is long, thus affecting the room heard the conditions, then the often inseparable from sound-absorbing materials on the reverberation time of adjustment. Such as large halls of cinemas, halls, concert halls, etc., according to their different listening requirements, choose the appropriate sound-absorbing materials, with size adjustment reverberation time, to listening clear, subjective feeling of fullness different requirements. From this point on, said sound-absorbing material shows the importance of its unique, so often said acoustical material often refers to the sound-absorbing material. Sound absorption and sound insulation fundamentally different, but in particular engineering applications, they are often together and play a comprehensive noise reduction. In theory, the amount to increase the absorption chamber, the equivalent of improved sound insulation partition walls. Common rooms have sound insulation, acoustic enclosures, wall panels made of composite sheet consisting of trunk roads of noise barriers, acoustic screens in the workshop, pipe wrap and so on. Sound-absorbing materials, such as used alone, can absorb and reduce the noise in the room where the sound source, but can not be effectively cut off from outside noise. When the sound-absorbing material and insulation material in combination use, or as part of the acoustic structure of sound-absorbing material, the favorable results generally showed improved sound insulation insulation structure. For a reasonable selection of materials to improve the effect of absorption and sound insulation of buildings, starting conceptually sound absorption, sound insulation, sound-absorbing materials, insulation materials separately, should be the primary building noise control basic issues. 

keywords: Acoustic materials, sound-absorbing materials, insulation materials,