基于阻抗反演技术的现场吸声测量研究  

In-situ measurement of sound absorption based on impedance inversion method

作　　者：孙亮[1] 侯宏[1] 

机构地区：[1]西北工业大学航海学院,陕西西安710072

出　　处：《振动工程学报》2011年第2期210-214,共5页Journal of Vibration Engineering

基　　金：国家自然科学基金资助项目(10674111);西北工业大学博士论文创新基金资助项目(CX200802)

摘　　要：吸声系数是针对平面波入射条件下定义的声学参量。在实际(或现场)测量时,往往不满足平面波入射条件。已有的三维空间吸声测量大都基于球面波入射条件,然后加以几何修正。由于与阻抗管测量时的平面波条件不同,所以两者的结果有一定差距。利用逆滤波器原理,对扬声器频响在高低频进行了相应的补偿,消除了环境噪声的影响,在三维空间产生了光滑的butterworth宽频声脉冲。另外,由于声源辐射面积相比测试样品尺寸小很多,可将脉冲声源近似为点声源。将butterworth声脉冲入射毛毡样本,利用在时域上能够分离的入射脉冲和反射脉冲,首先计算了球面波反射系数,然后采用牛顿下山法反演得到样本的平面波阻抗比,并进一步计算了吸声系数。结果表明:较之直接利用球面波几何修正的吸声系数,反演后的吸声系数与声管测量结果更为接近。本方法采用单传声器法(两次测量),测量过程简单,为现场吸声测试提供了一种新的技术途径。Sound absorption coefficient is usually defined in frequency domain for which the plane wave is used as incident wave,however,this situation may not be the case for in-situ measurement.Compared with the standard impedance tube method,the available methods through which the spherical wave is always used as a incident wave often give rise to unreliable results and need to be adjusted according to measurement arrangement.In this paper,the inverse filter principle was adopted to compensate the loudspeaker frequency response at higher and lower frequencies and butterworth pulse was then generated in non free-field room,during the process, the enviromental noise effect can also be eliminated.Besides this,the loudspeaker can be regarded as a point source when compared with the testing sample.Taking a felt sample with large area as the testing material,spherical reflection coefficient of which was obtained through the separated incident and reflected impulses in time domain,from which surface impedance and absorption coefficient for plane wave was also gained using the Newton-Rapshon inversion method.The final results indicate that inversion method can improve the measuring accuracy as well as reliability and can be applied to in-situ measurement when compared to conventional method.As single microphone is used in the measurement process,this method is relatively simple and can be used as an alternative method for in-situ sound absorption measurement.

关 键 词：声阻抗反演 butterworth脉冲 吸声系数 

分 类 号：TB95[一般工业技术—计量学]