![]() ![]() However, if acoustic energy is emitted in a low absorption room, the sound pressure levels inside can be increased by successive sound reflections. Anyway, the amount of energy involved in these phenomena is very little to cause a perceptible change of the surface temperature or shape. The dissipation that occurs in the pores and the microstructure of the material will be higher, and less energy will be reflected toward the room. It is related to the characteristics of the surface material, both in terms of its internal structure and its elasticity and texture: the more elastic or rough the surface is, the more energy will be absorbed, as it will deform more or the sound path will be increased the more through multiple reflections. The so-called absorbed energy is dissipated in the surface on which the sound waves impinge. To avoid this result, a suitable absorption treatment should be done on the surfaces of the room in order to reduce the reflections (the reverberation). If the room has low sound absorption, the sound pressure levels inside could eventually increase. When a good insulation is reached, a great amount of the incident energy is retained in the emission source room. Intuitively (but not strictly), the heavier the material is, the better insulation performance is expected. The more porous is a material, the less it insulates the more resistance to the flow of air a material presents, the better insulation performance it has. In other words, a good insulating material is bad for acoustic absorption, as a high value of α is related to a low value of τ. The more energy is absorbed, the less energy should be transmitted and vice versa. To achieve the acoustic quality objectives, working harmonically on insulation, absorption, and diffusion of sound is needed. ![]() It involves avoiding an undesired level of incidence of external noise and making the internal reverberation characteristics adequate for the desired use. so that a certain location is apt for one use. The acoustic project of enclosures involves the selection of materials to determine the type and quality of walls, surfaces, etc. There are different ways to attack a wide range of cases in order to achieve the desired acoustic quality at the receiver. To know if it is, some objectives and valid criteria must be selected and applied to compare with, in order to answer the question of “acceptable for what” or “for whom”. Noise control does not necessarily imply reduction of noise emissions it refers to making acceptable the sound level in immission (i.e., the signal that reaches the receiver). Noise control refers to a set of methods, techniques, and technologies that allow obtaining acceptable noise levels in a certain place, according to economic and operational considerations. The concepts of acoustic quality and noise control are often closely related. ![]()
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