After the analyses of acoustics property parameter and sound absorption performance of MR, the sound absorption performance parameter calculation formula and the acoustic property parameter relationship style are deduced and MR sound-absorbing peak value frequencies computational method is studied.
Meanwhile, the average transmission loss increases to 23 dB, and the average sound absorption coefficient increases 0.7. So the structure has obviously improved the sound absorption performance, it and the purpose is realized of broadband resonance sound absorption of low frequency.
The testing of sound absorbent property showed that the porous Alalloy has larger sound absorbent coefficient and the change of sound absorbent coefficient with sound frequency is the same,the sound frequency increases with the sound absorbent coefficient.
It decreased the anti-pressure of the gas inside the mold,which is favorable to the fabrication of thin hole (diameter 0.4~0.7 mm) porous aluminum. The problem has been solved that the infiltration is difficult in fabrication of the thin hole porous aluminum alloy. The testing results show that the sound absorbent property of the porous aluminum alloy in high frequency range is good.
By attaching para-aramid paper with less than 30 cc/sec/cm2 of permeability to nonwoven fabric, the sound absorption performance at over 2000 Hz was better than that of glass wool.