本试验方法包括使用阻抗管、两个传声器位置和数字频率分析系统来测定正常声入射时吸声器的吸声系数。它也可用于测定吸声材料的声表面阻抗或表面导纳。由于吸声材料的阻抗比与其物理特性（如气流阻力、孔隙率、弹性和密度）有关，因此本试验方法中所述的测量方法可用于基础研究和产品开发。 试验方法与ISO 10534-1中规定的试验方法相似，因为它使用一端连接有声源的阻抗管，另一端安装在管中的试样。然而，测量技术是不同的。 在本试验方法中，通过噪声源在管内产生平面波，通过使用壁装式传声器或管内横移传声器测量两个固定位置处的声压，并随后计算复声传递函数来实现干扰场的分解，声材料的正入射吸收和阻抗比。本试验方法旨在提供一种比ISO 10534-1更快的替代测量技术。 与iso354规定的混响室吸声量测量方法相比，存在一些特性差异。混响室法将（在理想条件下）确定漫射声入射的吸声系数，该方法可用于测试横向和法向结构明显的材料。 然而，混响室法需要较大的试件，因此不便于研究和开发工作，因为只有较小的吸声体样品。阻抗管法仅限于正入射时的参数研究，但需要与阻抗管横截面尺寸相同的试样。对于局部反应的材料，可以根据阻抗管法的测量结果来估计漫入射吸声系数。关于从阻抗管法（正入射）到漫射声入射的试验结果转换，见附录F。

This test method covers the use of an impedance tube, two microphone locations and a digital frequency analysis system for the determination of the sound absorption coefficient of sound absorbers for normal sound incidence. It can also be applied for the determination of the acoustical surface impedance or surface admittance of sound absorbing materials. Since the impedance ratios of a sound absorptive material are related to its physical properties, such as airflow resistance, porosity, elasticity and density, measurements described in this test method are useful in basic research and product development. The test method is similar to the test method specified in ISO 10534-1 in that it uses an impedance tube with a sound source connected to one end and the test sample mounted in the tube at the other end. However, the measurement technique is different. In this test method, plane waves are generated in a tube by a noise source, and the decomposition of the interference field is achieved by the measurement of acoustic pressures at two fixed locations using wall-mounted microphones or an in-tube traversing microphone, and subsequent calculation of the complex acoustic transfer function, the normal incidence absorption and the impedance ratios of the acoustic material. The test method is intended to provide an alternative, and generally much faster, measurement technique than that of ISO 10534-1. Compared with the measurement of the sound absorption in a reverberation room according to the method specified in ISO 354, there are some characteristic differences. The reverberation room method will (under ideal conditions) determine the sound absorption coefficient for diffuse sound incidence, and the method can be used for testing of materials with pronounced structures in the lateral and normal directions. However, the reverberation room method requires test specimens which are rather large, so it is not convenient for research and development work, where only small samples of the absorber are available. The impedance tube method is limited to parametric studies at normal incidence but requires samples of the test object which are of the same size as the cross-section of the impedance tube. For materials that are locally reacting, diffuse incidence sound absorption coefficients can be estimated from measurement results obtained by the impedance tube method. For transformation of the test results from the impedance tube method (normal incidence) to diffuse sound incidence, see annex F.