使用小型混响室进行随机入射吸声测试的实验室测量

[中文适用范围]： 本 SAE 推荐实践描述了一种实验室测试程序，用于通过测量衰减率来测量小尺寸混响室中材料或零件的随机入射吸声性能。吸收性能可以包括测试样品的吸声系数和/或测试样品吸收的能量的量。用于吸收处理的材料可以包括均质材料@非均质材料@或均质@非均质@和/或非弹性不渗透材料的组合。这些材料通常安装在移动产品和运输系统中，例如地面车辆@海洋产品@飞机@和商业行业（工业和消费品），以减少混响声音的积累，从而降低环境中的噪音水平通过最大限度地减少硬表面的反射。本文描述的测试方法还被开发来描述测量与应用相关的部件或声音封装系统的吸收性能的方法。它可用于对应用在使用通用汽车钢的面板上的材料进行排序，但也可适用于其他情况或条件。该测试程序专为在体积为 6 立方米至 25 立方米的房间内进行测量而开发。大多数材料和系统的吸收性能随着频率的变化而变化。因此，该测试程序包括测量适用于许多运输系统的频率范围内的吸收的规定。通常用于运输行业的样品不够厚，无法在低于 250 Hz 且在许多情况下低于 400 Hz 1/3 倍频程频率的情况下提供任何显着的吸收特性。结合样本大小和汽车及相关应用感兴趣的频率范围@该测试方法专为使用小型混响室进行测量而开发，其中感兴趣的频率范围低至 250 Hz 至 8000 Hz 1 /第三倍频程频率@取决于房间的体积。该测试方法的推荐房间体积为6m3至25m3。此处描述的测试方法与 ASTM C423 和 ISO 354 方法的不同之处在于，SAE 方法基于使用比 ASTM C423 或 ISO 354 方法中推荐尺寸的房间小得多的混响室。这不仅有助于测试小尺寸样本@，还可以测试车辆和其他运输系统@或其他应用产品的典型组件@零件@或子系统（非常接近如上所述的小尺寸样本）比 ASTM C423 或 ISO 354 测试方法更方便、更容易。该测试适用于对特定尺寸的材料和/或零件吸声性能进行排序，而不是重复其他尺寸样品的结果。通过 SAE 方法获得的结果可能与 ASTM C423 或 ISO 354 的结果不同，因为房间体积和样本大小可能会显着影响测量的吸收率。此推荐做法无意取代 ASTM C423 或 ISO 354 测试标准。 [外文原描述]： 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 6m 2x to 25m 2x in 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 1/3 2x octave 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 1/3 2x octave band frequency, depending on the volume of the room. The recommended volume of the room for this test method is from 6m 2x to 25m 2x.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.Cross Reference: ANSI S1.1,ANSI S1.11,ANSI S1.26,ASTMC423,ASTME691,ASTME795,ISO 18233,ISO 3382-2,ISO 354,ISO 3741,J1355_201708,J2629_201508,TSB 003