1.1本试验方法包括使用一根管子、四个麦克风和数字频率分析系统，通过测定声学传递矩阵来测量正常入射传输损耗和材料的其他重要声学特性。 1.2以国际单位制表示的数值应视为标准值。本标准不包括其他计量单位。 1.3 本标准并非旨在解决与其使用相关的所有安全问题（如有）。本标准的用户有责任在使用前制定适当的安全和健康实践，并确定监管限制的适用性。 ====意义和用途====== 该测试有几个目的: 对于传输损耗: （a） 与试验方法E 90相比，采用成本更低、耗时更少的方法表征材料的隔音特性 和ISO 140-3( “ 混响室法 ” ), （b） 当大样本无法建造或运输时，允许测试小样本， （c） 允许使用无需经验丰富的专业人员即可运行的快速技术。 对于传输矩阵: （a） 确定材料的其他声学特性； （b） 允许通过组合单个传递矩阵计算组合材料或复合材料的声学特性。 该方法与更传统的混响室方法之间存在显著差异。 具体来说，在这种方法中，声音以垂直方向冲击试样( “ 正常发病率 ” )只是，与传统的随机关联方法相比。此外，复混流室方法规定了试样的某些最小尺寸，这可能不适用于所有材料。目前，这两种方法之间的相关性（如果有的话）尚不清楚。尽管该方法可能无法复制用于测量材料传输损耗的混响室方法，但它可以为小样本提供比较数据，这是混响室方法无法做到的。在某些情况下，当材料放置在靠近声源的小声腔中时，例如，近距离声源，正入射传输损耗也可能有用- 安装机器外壳或便携式电子设备。 传输损耗不仅是材料的特性，而且在很大程度上取决于方法中固有的边界条件和材料安装方式的细节。在解释通过本试验方法获得的结果时，必须考虑到这一点。 测量量是频率的函数，分辨率由采样率、变换大小和数字频率分析系统的其他参数决定。可用频率范围取决于管的直径和麦克风位置之间的间距。通过使用不同直径和麦克风间距的管子，可以获得更大的频率范围。 材料在声学系统元件中的应用可能与本试验方法不同，因此通过本方法获得的结果可能与- 原位。

1.1 This test method covers the use of a tube, four microphones, and a digital frequency analysis system for the measurement of normal incident transmission loss and other important acoustic properties of materials by determination of the acoustic transfer matrix. 1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. ====== Significance And Use ====== There are several purposes of this test: For transmission loss: (a) to characterize the sound insulation characteristics of materials in a less expensive and less time consuming approach than Test Method E 90 and ISO 140-3 ( “ reverberant room methods ” ), (b) to allow small samples tested when larger samples are impossible to construct or to transport, (c) to allow a rapid technique that does not require an experienced professional to run. For transfer matrix: (a) to determine additional acoustic properties of the material; (b) to allow calculation of acoustic properties of built-up or composite materials by the combination of their individual transfer matrices. There are significant differences between this method and that of the more traditional reverberant room method. Specifically, in this approach the sound impinges on the specimen in a perpendicular direction ( “ normal incidence ” ) only, compared to the random incidence of traditional methods. Additionally, revereration room methods specify certain minimum sizes for test specimens which may not be practical for all materials. At present the correlation, if any, between the two methods is not known. Even though this method may not replicate the reverberant room methods for measuring the transmission loss of materials, it can provide comparison data for small specimens, something that cannot be done in the reverberant room method. Normal incidence transmission loss may also be useful in certain situations where the material is placed within a small acoustical cavity close to a sound source, for example, a closely-fitted machine enclosure or portable electronic device. Transmission loss is not only a property of a material, but is also strongly dependent on boundary conditions inherent in the method and details of the way the material is mounted. This must be considered in the interpretation of the results obtained by this test method. The quantities are measured as a function of frequency with a resolution determined by the sampling rate, transform size, and other parameters of a digital frequency analysis system. The usable frequency range depends on the diameter of the tube and the spacing between the microphone positions. An extended frequency range may be obtained by using tubes with various diameters and microphone spacings. The application of materials into acoustical system elements will probably not be similar to this test method and therefore results obtained by this method may not correlate with performance in-situ.