扩散吸声体设计中的护面层影响研究

On the Effect of Cladding in Diffsorber Design

扩散吸声体(diffsorber)共振吸声时,由于闭管的内阻抗和辐射阻抗往往不能匹配,造成吸声的效果在高频有所下降,为解决此问题,可以在扩散吸声体表面覆盖一层护面材料加以改善。利用护面层本身的声学作用,增加闭管管口的声阻,使闭管的内阻与辐射阻在高频时更好匹配,进一步提高高频时的吸声效果,使得扩散吸声体在很宽的频带范围内都能起到良好的吸声作用。实验表明,选取合适的护面层可以使扩散吸声体单位面积吸声量在中低频段可达1.4 m2,在高频时亦能达到1.2 m2,吸声的效率很高。所提的理论模型与实验结果协调得较好,可以对扩散吸声体的性能作进一步优化。

In resonance, diffsorber only has a low sound absorption effect in high frequency range because the intemal impedance in the tube and the radiation impedance outside the tube do not match each other. A cladding on the surface of the diffsorber will have some positive improvement for solving this problem. Using acoustic cladding can increase the acoustic impedance in the tube, so that the intemal resistance and radiation resistance at high frequencies can match better. And the diffsorber can have a good sound absorption in a wide frequency range. Experiments show that selecting the appropriate cladding allows diffsorber to have up to 1.4 m2 absorption areas per unit square meter at low and medium frequencies, and 1.2 m2 at high frequencies. So the sound absorption is very efficient. Result of the theoretical model proposed in this paper is in good agreement with the experimental result. Thus, this method can be used to further optimize the performance of the diffsorber.