本SAE推荐规程描述了通过测量衰减率来测量小型混响室内材料或零件的随机入射吸声性能的实验室试验程序。吸收性能可包括试样的吸声系数和/或试样吸收的能量。用于吸收处理的材料可包括均质材料、非均质材料或均质、非均质和/或非弹性防渗材料的组合。这些材料通常安装在移动产品和运输系统中，如地面车辆、海洋产品、飞机和商业行业（工业和消费品），以减少混响- 通过减少硬表面的反射，从而降低环境中的噪音水平。本文所述的测试方法也是为了描述一种测量与应用相关的部件或声包系统的吸收性能的方法。它可用于对订单材料进行排序，以便在使用通用汽车钢的面板上使用，但也可适用于其他情况或条件。本试验程序适用于在体积为6m3至25m3的房间内进行的测量。大多数材料和系统的吸收性能随频率的变化而变化。 因此，本试验程序包括在适用于许多运输系统的频率范围内测量吸收的规定。通常用于运输行业的样品厚度不足以在250 Hz以下提供任何显著的吸收性能，在许多情况下，低于400 Hz 1/3倍频程频率。结合汽车和相关应用的样品尺寸和感兴趣的频率范围，开发了本试验方法，用于使用小型混响室进行测量，其中感兴趣的频率范围为250 Hz至8000 Hz 1/3倍频程频率，具体取决于房间的体积。 本试验方法的推荐房间体积为6m3至25m3。此处描述的试验方法不同于ASTM C423和ISO 354方法，因为SAE方法基于使用比ASTM C423或ISO 354方法中推荐尺寸小得多的混响室。这不仅有助于测试小尺寸样品，还允许测试车辆和其他运输系统的典型部件、零件或子系统（与上述小尺寸样品接近），或比ASTM C423或ISO 354测试方法更方便、更容易地用于其他应用的产品。 本试验适用于对特定尺寸的材料和/或零件的吸声性能进行排序，且不打算重复其他尺寸样品的结果。SAE方法获得的结果可能不同于ASTM C423或ISO 354的结果，因为房间体积和样品尺寸可能会显著影响测量的吸收。本推荐规程无意取代ASTM C423或ISO 354测试标准。

This SAE Recommended Practice describes a laboratory test procedure for measuring the random incidence sound absorption performance of a material or a part in a small size reverberation room by measuring decay rates. The absorption performance may include sound absorption coefficient of the test sample and or the amount of energy absorbed by the test sample. Materials for absorption treatments may include homogeneous materials, nonhomogeneous materials, or a combination of homogeneous, nonhomogeneous, and/or inelastic impervious materials. These materials are commonly installed in the mobility products and in the transportation systems such as ground vehicles, marine products, aircraft, and commercial industry (in industrial and consumer products) to reduce reverberant sound build-up and thus reduce the noise level in the environment by minimizing reflections off of hard surfaces. The test method described herein was developed also to describe a way to measure the absorption performance of a part or a sound package system that will relate to an application. It can be used to rank order materials for application on panels using general automotive steel but also may be applicable to other situations or conditions. This test procedure has been developed for measurements made in rooms between 6m3to 25m3in volume.The absorption performance for most materials and systems varies as a function of frequency. Accordingly, this test procedure includes provisions for measuring absorption over a frequency range found applicable to many transportation systems. Samples that are used typically in the transportation industry are not thick enough to provide any significant absorptive properties below 250 Hz and in many cases below 400 Hz 1/3rdoctave band frequency. Combining the size of the sample and the frequency range of interest for automotive and related applications, this test method has been developed for conducting measurements using a small reverberation room where the frequency range of interest would be from as low as 250 Hz to 8000 Hz 1/3rdoctave band frequency, depending on the volume of the room. The recommended volume of the room for this test method is from 6m3to 25m3.The test method described here differs from the ASTM C423 and the ISO 354 methods in that the SAE method is based on using a significantly smaller size reverberation room than the recommended size room in the ASTM C423 or ISO 354 methods. This aids not only to testing a small size sample, but also allows testing a typical component, part, or a subsystem (that approximates closely to a small size sample as mentioned above) of a vehicle and other transportation systems, or products for other applications more conveniently and easily than the ASTM C423 or the ISO 354 test method. This test is appropriate to rank order a specific size material and/or part sound absorption properties and not intended to duplicate the results of other size samples. The results obtained by the SAE method may be different from that of the ASTM C423 or the ISO 354 as the room volume and the sample size may significantly impact the measured absorption. This recommended practice is not intended to replace the ASTM C423 or the ISO 354 test standard.