基于修正传递函数的消声器传声损失测量

Measurement of Transmission Loss of Muffler Based on Corrected Transfer Function

基于平面波假设,推导了4传声器位置、双终端边界条件互谱法传声损失测量基本原理;在此基础上,提出了采用4传声器位置、双边界条件、基于传递函数的传声损失测量分析改进算法。与互谱法相比,基于修正传递函数的传声损失测量分析法具有明显优势,主要表现为传递函数的分批测量可以最小化测量系统的硬件需求,可以采用传声器位置互换法来提高传递函数的测试精度。以B&K的声学材料测试系统为硬件平台,对典型扩张式消声器进行了传声损失测量分析。结果表明:传递函数修正后的分析结果准确性相比修正前有显著提高。

Based on the theory of plane wave,the formulae of sound transmission loss was deduced by using measured cross-spectrum functions at 4 microphone positions under 2 boundary conditions.An algorithm using corrected transfer function was put forward.Compared to the method based on cross-spectrum,the method based on the corrected transfer function has two obvious advantages： The hardware requirements can be minimized because the transfer functions can be measured in batches;The measurement precision of transfer functions can be improved based on two measurements with the interchanged microphone positions.The experiment for transmission loss of an expansion muffler was conducted using the hardware platform of B＆K acoustical material testing system.The results show that the transmission loss based on corrected transfer function is more accurate than that based on uncorrected transfer function or cross-spectrum.