对称消声器传递损失测量及误差修正

为了提高对称消声器传递损失的测量效率，基于声学理论分析，提出了一种单负载法传递损失计算模型。针对反射系数较大的吸声末端，导致该方法在实际测量中存在较大误差的问题，推导出了一种能够消除测试管道末端反射声波在上、下游形成多次反射的修正公式。通过自制阻抗管进行试验测试，结果表明：在末端声学负载吸声性能良好的情况下，单负载法传递损失计算模型能够精确计算出对称消声器的传递损失；修正公式能够有效地消除末端负载所引起的反射波对传递损失计算的影响，降低对末端声学负载吸声性能的要求，保证单负载传递损失计算模型的适用性。

Research on Transmission Loss Measurement and Error Correction of Symmetric Muffler

In order to improve the measurement efficiency of symmetric muffler transmission loss, we explore the mutual correspondence between incident sound wave and reflected sound wave in the upstream and downstream pipelines of different sound source positions, and propose a single load transmission loss calculation model suitable for various types of mufflers, based on the theoretical analysis of two-source method. To decrease the difference between the calculated result and actual measurement result which caused by the large reflection coefficient at the sound absorption end, a modified formula has been derived to eliminate the multiple reflections of the transmitted reflection sound wave at the end of the test pipe. Three typical mufflers have been tested by self-made impedance tube. The results show that the single load calculation model can accurately calculate the transfer loss of the symmetric muffler when the sound absorption performance of the acoustic load at the end is good. The modified formula can effectively eliminate the influence of the reflected wave caused by the acoustic terminal load on the calculation model of the single-load transmission loss, can reduce the requirement on the acoustic absorption performance of the terminal acoustic load, and ensure the applicability of the calculation model of the single load transmission loss.