边缘效应对混响室法测量吸声系数影响的研究

Research on the Influence of Edge Effect on Absorption Coefficient Measurement by Reverberation Chamber Method

边缘效应对混响室法测量吸声系数影响的研究中,大多是通过改变试件面积和排列方式来从侧面研究边缘效应,一直以来缺少对边缘效应影响的直接研究。本研究以玻璃棉为例对边缘效应的影响进行直接研究,具体研究方法是在标准混响室内,通过混响室内设置的升降平台的上下移动,可以得到材料表面高出或与地面平齐的不同情况,以达到存在或消除试件边缘效应的效果,进行对比研究,得到不同状况下相应的混响时间,计算出在不同情况下的吸声系数。研究结果表明,对于玻璃棉来说,在高频段上边缘效应使得其吸声系数有所提高,但不是导致吸声系数大于1的唯一因素,从总体上来看,边缘效应的影响有限。

There has been a lack of a direct research of edge effect on the measurement of sound absorption coefficient by reverberation chamber method,while most researches are conducted with a change in the size and arrangement of specimen. By taking glass wool material as a test sample,this paper carried out a direct research on edge effect. By using a lifter in a standard reverberation room,the test sample was moved up or down to make its top surface t above or flushed with the ground in order to retain or eliminate the edge effect,figuring out the corresponding reverberation time in different conditions,as well as the absorption coefficients under different circumstances. The research results show that the sound absorption coefficient of glass wool was increased by edge effect on high-frequency bands,but it was not the only factor making the absorption coefficient greater than 1.However,as a whole,edge effect is limited on the sound absorption coefficient.