驻波管法四传声器测量隔声量的误差分析

Analysis of the Tolerance of Sound Transmission Loss Measured by Four-Microphone in Standing Wave Tube

通过对驻波管四传声器测量隔声量的研究,发现波数与传声器间距之积(ks)对于隔声量计算误差具有一定的影响.进而从误差传递的角度出发,对方程组的条件数进行全面分析,找到了测量误差在求解过程中放大较小时,波数与传声器间距之积应满足(0.3+n)π≤ks≤(0.7+n)π,n=0,1,2,…的条件.同时,提出了一种通过测量误差对计算误差进行估计的方法,并从概率的角度对测量误差σ分别为0.1、0.3、0.5、0.7、0.9 dB进行了分析,得到了相应的隔声量计算误差的期望为0.5、1.5、2.6、3.7、4.9 dB,从而为传声器的选择和间距布置提供一种依据.

In the research of the method of measuring sound insulation with four-microphone in standing wave, the product（k · s） of wave number and space between microphones is verified to have the influence on the computing error of sound insulation. In the view of computing error transmission and by the comprehensive analysis on the condition number of the system equations, it was found that to reduce the metrical error in the solving process the product of wave number and space between microphones should satisfy the condition （0.3＋n）π≤ks≤（0.7＋n）π,n=0,1,2,… . Meanwhile, a method to evaluate the computing error of sound insulation through the metrical error was proposed, and the computing error analysis was made using the probability when the metrical error is 0.1,0. 3,0. 5,0. 7,0. 9 dB, and the corresponding expecting computing error is 0. 5,1. 5,2. 6,3. 7,4. 9 dB respectively. So a rule in the microphones choosing and setting was provided.