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Sound-absorbing materials and sound-absorbing structure

By sound-absorbing mechanism, commonly used in sound-absorbing materials and sound-absorbing structure can be divided into porous sound-absorbing materials and resonant sound absorption structure.????1, porous sound-absorbing material????Porous sound-absorbing materials include fiber and particle materials. Fiber materials are: glass wool, ultra-fine glass wool, mineral wool and other inorganic fibers and carpet, sheet products, cotton, wool, hemp and other organic fabrics. Granular material has expanded perlite, porous brick panels block, plate products.????Porous sound-absorbing materials in general have a good high-frequency sound absorption performance, not because of a rough surface absorption mechanism, but because it has a large number of internal and external connectivity, the tiny gap bubbles. The sound absorption capacity of porous materials and their thickness, density related with the thickness of the increase in the low-frequency sound absorption coefficient of a significant increase in high-frequency change little. Increase the density of the material can also increase the low-frequency absorption coefficient, but lower than the effect of increasing the thickness is small, so using the same materials, when the thickness of restrictions, the preferred structure, the thickness of a large density of loose porous materials.????Whether the air layer behind the porous materials, have a major impact on the sound absorption properties. Along with its acoustic properties of the air layer thickness increased with the increase.????Curtain is also a good porous sound-absorbing material. The absorption effect is concerned, the best velvet, velveteen second, cotton and linen fabrics once again, the worst chemical class curtain. By adjusting the curtain walls or glass with adjustable sound-absorbing effect of the spacing.????2, resonance absorption structure????Perforation plate structure and sound absorption sheet, film sound-absorbing structure can be regarded as principles of the use of acoustic resonance absorption structure.????Perforation plate structure has a better sound absorption characteristics of mid-frequency sound absorption. It consists of metal plates, thin wood, gypsum board, etc. to wear a certain density of holes or cracks after the fixed keel, leaving behind the air layer which constitutes a resonant acoustic system. It is the grounds of a number of parallel visual Helmholtz resonator formed.????Resonance frequency can be calculated by:????Type of C - speed of sound, 34 × 103cm / s????P - wear a Sound rate, which is perforated area to total area ratio;????D ---- Thickness (CM)????d ---- perforation diameter (CM)????Characteristics of perforated plate acoustic resonance frequency in the vicinity of the maximum absorption coefficient. In order to expand the frequency range of absorption coefficient can be perforated board after the laying of porous sound-absorbing material, and leave a certain air gap.????Perforation of the aperture is less than 1MM (perforation rate of P = 1% ~ 3%) referred to as microplates, using thin metal plate made of porous lay behind it and then sound-absorbing material can be in relatively good broadband absorption within the sound effect. Micro-perforated plates made of double-decker structure, and absorption better performance.????If the perforation rate of over 50% of the micro-perforated metal film or a porous plexiglass plate directly posted on the large-scale decorative glass plane, you can solve the flat glass, the strong acoustic emission problems, while not very much affected by light transmittance of glass or transparency. His drawback is that too expensive.????3, acoustic diffusers more speaker,loudspeaker,jbl speaker,hi fi speaker,speaker wholesale made in our speaker factory and speaker manufacturer