Introduction of perforated plate resonance sound absorption structure

Perforated plate resonance sound-absorbing structure is a thin plate, such as steel plate, aluminum plate, plywood, plastic plate, calcium silicate plate, cement pressure plate, gypsum board, etc., perforated according to a certain aperture and perforation rate, leaving a certain thickness of air layer behind, forming a perforated plate resonance sound-absorbing structure.

The relationship between the perforated plate resonance sound absorption structure and the noise frequency: when the sound waves of different frequencies are incident, the resonance system will produce different responses. When the frequency of the incident sound waves is close to the inherent resonance frequency of the system, the vibration of the air in the system is very strong and the sound energy is greatly lost, that is, the sound absorption effect is the best. On the contrary, when the frequency of the incident sound waves is far from the inherent resonance frequency of the system, the vibration of the air in the system is very weak, Therefore, the effect of sound absorption is very small. The sound absorption coefficient of this resonance sound absorption structure changes with the frequency, and the highest sound absorption coefficient appears at the resonance frequency of the system. At present, the sound absorption principle of the widely used micro-perforated panel sound absorption structure also belongs to this type.

Sound absorption principle of perforated plate resonance sound absorption structure

Perforated plate resonance sound absorption structure is actually a resonance sound absorption structure composed of many single resonators in parallel. A small hole is opened on the wall of the closed cavity to communicate with the external air. Because the hole diameter and hole length are smaller than the wave length of the sound wave, the elastic deformation of the air column in the hole is very small, which can be seen as an invisible mass. The air in the cavity vibrates elastically with the sound wave, which is equivalent to a spring. If the reflected sound waves excite the aperture, the air column moves back and forth and rubs against the radial wall, and part of the sound energy is converted into heat energy and consumed to achieve the purpose of sound absorption. When the frequency of the incident sound wave is the same as the natural frequency of the resonator, resonance occurs, the movement of the air column intensifies, the amplitude and vibration speed reach the maximum, the damping is also the largest, the sound energy consumption is the largest, and the sound absorption performance is the best.

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