Research on Mid-Low Frequency Noise Reduction Material and Its Structure Design 2021-01-0815

Aiming at the problem of middle and low frequency noise absorption, a combined sound-absorbing structure is designed based on porous material and a coiled-up cavity resonance structure. Combined with the sound absorption principle of porous materials and coiled-up cavities, a theoretical analytical model was established. By the finite element method, the sound absorption coefficient curve of the combined structure in a frequency range of 500-2000Hz is calculated, and the correctness of the analytical calculation and the finite element simulation calculation was verified in the impedance tube experiment. The results show that the combined structure has good sound absorption performance in the 500Hz-2000Hz frequency band, and the sound absorption peak appears near the 1108Hz frequency, reaching nearly perfect sound absorption. Compared with a single porous material, the sound absorption performance of the combined structure is better. Combining with the resonance peak frequency calculated by the effective length of the coiled-up cavity resonant structure and the resonance peak frequency calculated by the actual simulation, the sound absorption mechanism of the combined structure is further analyzed. Secondly, By analyzing the influence of different volume ratios of porous materials on the overall sound absorption performance in the combined structure, and the results show that the peak sound absorption frequency increased, and the sound absorption frequency band increased slightly.