声学阻抗管声学特性的测定第2部分:法向吸声系数和法向表面阻抗的双传声器技术

[中文适用范围]： 本测试方法涵盖了使用阻抗管、两个麦克风位置和频率分析系统来确定吸声材料在垂直入射声入射下的吸声系数。它还可用于确定吸声材料的声表面阻抗或表面导纳。作为扩展，它还可用于评估均质声学材料的固有特性，例如其特性阻抗、特性波数、动态质量密度和动态体积模量。该测试方法类似于 ISO 10534-1[1] 中规定的测试方法，因为它使用阻抗管，其一端连接声源，另一端将测试样品安装在管中。但是，测量技术不同。在该测试方法中，声源在管中产生平面波，通过使用壁挂式麦克风或管内横向麦克风测量两个固定位置的声压，然后计算上一段中报告的复杂声学传递函数和量，从而实现干扰场的分解。该测试方法旨在提供一种比 ISO 10534-1[1] 更快的替代测量技术。阻抗管测量得到的法向入射吸收系数与根据扩散声入射的吸收系数在混响室中测得的随机入射吸收系数不可比。然而，混响室方法需要相当大的测试样本。阻抗管法仅限于法向和平面入射的研究，并且需要测试对象的样本与阻抗管的横截面积相同。对于仅局部反应的材料，可以根据阻抗管法获得的测量结果估算扩散入射声吸收系数（见附件 E）。在整个文件中，使用 aejt + ω 时间约定。 [外文原描述]： This test method covers the use of an impedance tube, two microphone locations and a frequency analysis system for the determination of the sound absorption coefficient of sound absorbing materials for normal incidence sound incidence. It can also be applied for the determination of the acoustical surface impedance or surface admittance of sound absorbing materials. As an extension, it can also be used to assess intrinsic properties of homogeneous acoustical materials such as their characteristic impedance, characteristic wavenumber, dynamic mass density and dynamic bulk modulus. 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 sound 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 and quantities reported in the previous paragraph. The test method is intended to provide an alternative, and generally much faster, measurement technique than that of ISO 10534 - 1 . Normal incidence absorption coefficients coming from impedance tube measurements are not comparable with random incidence absorption coefficients measured in reverberation rooms according to ISO 354 . The reverberation room method will (under ideal conditions) determine the sound absorption coefficient for diffuse sound incidence. However, the reverberation room method requires test specimens which are rather large. The impedance tube method is limited to studies at normal and plane incidence and 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 only, diffuse incidence sound absorption coefficients can be estimated from measurement results obtained by the impedance tube method (see Annex E ).