1.1 本试验方法涵盖了对消声装置的一些声学特性的实验室测试，包括建筑物通风系统中使用的管道内衬材料、整体管道和管道内吸收式直管和弯管消声器。描述了声插入损耗、气流产生的噪声和压降随气流变化的测量程序。 1.2 不包括反应式消声器和设计用于通风系统以外用途的消声器，如汽车消声器。 1.3 该试验方法包括一个模拟半反射腔室，用于安装在薄壁管道和消音器试样周围，因为此类薄壁管道周围的声学环境- 有壁试样可能会影响测量的插入损耗。 1.4 该方法在定义明确且受控的条件下测试试样的性能。如果样本以任何不同的方式安装在现场，结果可能不同。本标准不提供在现场条件下确定试样实际安装性能的估算程序。 1.5 以国际单位制表示的数值应视为标准值。括号中的值仅供参考。 1.6 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、健康和环境实践，并确定监管限制的适用性。 1.7 本国际标准是根据世界贸易组织技术性贸易壁垒（TBT）委员会发布的《关于制定国际标准、指南和建议的原则的决定》中确立的国际公认标准化原则制定的。 ====意义和用途====== 5.1 使用本标准测试的样本，例如管道消音器，用于控制通过通风管道的声音传播。根据本标准从测试样本中收集的结果可用于估计管道气流系统中因在系统中安装消声装置而导致的风扇声级降低。设备可以是源中的组件- 路径接收器分析，其中执行计算以确定占用空间中的合成声级。正确选择声音衰减装置可以使设计师达到空间背景噪声标准。 5.2 消声器的插入损耗随频率、气流方向和速度而变化。由于消音器部分阻塞了空气通道并对气流产生阻力，因此必须量化另外两种影响:压降和气流产生的噪声。两者都随着空气速度的增加而增加；因此，需要多个气流的数据来正确表征性能。 5.3 根据标准测试样本的空气动力学结果可作为系统设计工程师的信息，以确定系统风扇要克服的静态压降阻力。 设计界已根据本文所述程序制定了消声元件适当最大允许压降的指南。 5.4 如前所述 1.4 在本试验方法中，安装在风道系统中的消声装置的实际性能可能与根据本文试验程序报告的性能显著不同。本标准不为用户提供有关这些系统影响的指导。 5.5 消声器通常设计为在不重复本标准试验设置的条件下使用。用于确定非标准配置中声音衰减装置性能的实体模型和专用测试装置可以基于本测试方法，但不能被视为完全符合本测试方法。 看见 附件A2 有关此类测试的更多信息。

1.1 This test method covers the laboratory testing of some of the acoustical properties of sound attenuating devices including duct liner materials, integral ducts, and in-duct absorptive straight and elbow silencers used in the ventilation systems of buildings. Procedures are described for the measurement of acoustical insertion loss, airflow generated noise, and pressure drop as a function of airflow. 1.2 Excluded from the scope are reactive mufflers and those designed for uses other than in ventilation systems, such as automobile mufflers. 1.3 This test method includes a provision for a simulated semi-reflective plenum to fit around thin-walled duct and silencer test specimens, since the acoustical environments around such thin-walled specimens can affect the measured insertion loss. 1.4 This method tests the performance of the specimen in well-defined and controlled conditions. If the specimen is installed in the field in any different manner, the results may be different. This standard does not provide estimating procedures for determining the actual installed performance of the specimen under field conditions. 1.5 The values stated in SI units are to be regarded as standard. The values in parentheses are provided for information only. 1.6 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use. 1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee. ====== Significance And Use ====== 5.1 Specimens tested using this standard, for example, duct silencers, are used to control sound propagation through ventilation ducts. The results gathered from testing specimens to this standard can be used to estimate the reduction in fan sound levels in ducted airflow systems caused by including a sound attenuating device in the system. The device can be a component in a source-path-receiver analysis where calculations are performed to determine the resultant sound level in an occupied space. Correct selection of a sound attenuating device can enable a designer to achieve in-space background noise criteria. 5.2 The insertion loss of a silencer varies with frequency and with the direction and speed of airflow. Because silencers partially obstruct the air path and provide resistance to airflow, two other effects must be quantified: pressure drop and airflow-generated noise. Both increase with increasing air speeds; thus data are required for several airflows to correctly characterize performance. 5.3 The aerodynamic results from testing specimens to the standard can be used as information for the system design engineer to determine the amount of static pressure drop resistance to be overcome by the system fan(s). Guidelines for appropriate maximum allowable pressure drop for a sound attenuating element have been established in the design community and are based on the procedures described herein. 5.4 As stated previously in 1.4 of this test method, the actual performance of a sound attenuating device as installed in an air duct system may be significantly different than reported based on the test procedure herein. This standard does not provide guidance to the user on these system effects. 5.5 Silencers are often designed to be used under conditions which do not duplicate the test set-ups of this standard. Mock-ups and specialized test set-ups to determine performance of sound attenuating devices in non-standard configurations may be based on this test method but cannot be considered to be in full conformance with this test method. See Annex A2 for further information regarding such tests.