阶梯状声扩散体排布方式对扩散性能影响分析

Stepped sound diffuser arrangement and diffusion analysis

应用时域有限差分法计算阶梯状声扩散体的反射声场,通过理论计算结果和全消声室测量结果对比证明了计算方法的有效性。在近似远场条件下,传声器、声源与扩散体之间的距离对扩散系数计算结果没有影响。将声场时域有限差分法与免疫遗传算法相结合对单周期六阶阶梯状扩散体的形体进行优化。优化后的单周期扩散体的扩散性能优于原扩散体,但经周期排布后,两者的扩散性能均降低。依二进制序列排布正反相扩散体,通过寻优计算得到扩散体排布,其整体扩散性能优于传统的周期重复排布方式,但没能获得平直的扩散系数频率特性曲线。将优化后的阶梯状扩散体与原扩散体按照二进制序列混合排布,通过寻优计算得到扩散体排布进一步提高了整体扩散性能。

Diffuser sound scattering was predicted using the finite difference time domain(FDTD) method. There were no obvious differences in the diffusion coefficient when changing the distance between the diffuser and the receivers or source in the approximate far field. Then, FDTD was combined with the immune genetic algorithm to optimize the shape of a 6 th order stepped sound diffuser which had better diffusion than the original diffuser. The sound scattering from the two diffusers became less diffuse when repeated over many periods. An aperiodic modulation method was used to combine a diffuser and its inverse diffuser using a binary code. Tests show that aperiodic modulated diffusers have better diffusion than periodic diffusers;however, this modulation cannot produce a flat diffusion coefficient curve, so the best diffusion is obtained by arranging the optimized stepped diffuser with the original diffuser together using a binary code.