Explanation

The perforated plate resonance sound absorption structure is a structure formed by punching holes in steel plate, aluminum plate or other non-metallic plywood, plastic board, straw cardboard, gypsum board, etc. with a certain aperture and perforation rate, and leaving a cavity of a certain thickness behind. The perforated plate resonance sound absorption structure absorbs sound by relying on the resonance of the system. Since the back of each orifice on the perforated plate contains a corresponding cavity, the cavity is actually a parallel combination of numerous continuous single Helmholtz resonators. The connecting cavity of the small hole air column of the resonator can be regarded as a single degree of freedom vibration system composed of mass and spring. Its natural frequency is where S is the area of the hole neck, m2; V is the volume of the cavity, is the length of the orifice neck, tn; 5 is the correction amount at the end of the orifice, m. When sound waves shoot vertically onto the surface of a perforated plate? The air inside and around the hole vibrates back and forth with sound waves, acting as a piston that resists changes in volume velocity; The air layer between the perforated plate and the wall acts as a spring to prevent changes in sound pressure; In addition, due to the frictional damping of air oscillating back and forth near the perforation, it can consume sound energy. When sound waves of different frequencies are emitted by humans, this resonance system will produce different responses. When the frequency of sound waves emitted by humans approaches the inherent resonance frequency of the system, the vibration of the air inside the system is strongest and the sound absorption is maximum. Perforated panels mainly absorb medium and low frequency noise, with a sound absorption coefficient of around 0.6. They are widely used in acoustic decoration projects with high requirements for sound quality. When used, porous sound absorbing materials is placed in the cavity of perforated panel sound absorption structure, which can increase the sound absorption coefficient and broaden the effective sound absorption band.

Classification