1.1 本试验方法包括通过测量衰减率来测量混响室中的吸声率。描述了测量房间的吸收率、物体（如办公室屏幕）的吸收率以及吸音材料（如吸音天花板砖）试样的吸声系数的程序。 1.2 现场测量-- 虽然该测试方法涵盖了实验室测量，但 4.1 可用于对房间的吸收进行现场测量（另见 5.5 ). 《试验方法》中描述了一种测量现场房间吸收率的方法 E2235 . 1.3 该测试方法包括实验室认证信息（见 附件A1 )，不对称屏幕（参见 附件A2 )，以及混响室资格（见 附件A3 ). 1.4 以国际单位制表示的值应被视为标准值。本标准不包括其他计量单位。 1.5 本标准并不旨在解决与其使用相关的所有安全问题（如果有的话）。本标准的使用者有责任在使用前建立适当的安全、健康和环境实践，并确定监管限制的适用性。 1.6 本国际标准是根据世界贸易组织技术性贸易壁垒委员会发布的《关于制定国际标准、指南和建议的原则的决定》中确立的国际公认的标准化原则制定的。 =====意义和用途====== 5.1 测量房间的吸声率是其他声学测量程序的一部分，例如确定噪声源的声功率级或隔墙的声传输损失。它也用于某些计算，例如在已知房间中噪声源的声功率级时预测房间中的声压级。 5.2 表面的吸声系数是构成表面的材料的特性。理想情况下，它被定义为表面吸收的随机入射声功率的分数，但在这种测试方法中，它在操作上被定义为 4.2 理论定义的系数与实际测量的系数之间的关系正在继续研究中。 5.3 衍射效应 4. 通常会导致试样的表观面积大于其几何面积，从而增加根据本试验方法测量的系数。 当试样具有高吸收性时，这些值可能会超过1。 5.4 应谨慎使用该测试方法测量的系数，因为不仅在实际使用中遇到的面积通常大于试样，而且声场很少扩散。在实验室中，必须在可重复的条件下进行测量，但在实际使用中，决定有效吸收的条件往往是不可预测的。尽管存在差异和判断的必要性，但建筑师和顾问在建筑空间的声学设计中成功地使用了这种测试方法测量的系数。 5.5 现场测量-- 当在房间大小和形状不受操作员控制的建筑物中进行吸声测量时，扩散声场的近似值不太可能非常接近。 在评估现场条件下测量的准确性时，应考虑此事。（见试验方法 E2235 适用于现场使用不太复杂仪器的程序。）

1.1 This test method covers the measurement of sound absorption in a reverberation room by measuring decay rate. Procedures for measuring the absorption of a room, the absorption of an object, such as an office screen, and the sound absorption coefficients of a specimen of sound absorptive material, such as acoustical ceiling tile, are described. 1.2 Field Measurements— Although this test method covers laboratory measurements, the test method described in 4.1 can be used for making field measurements of the absorption of rooms (see also 5.5 ). A method to measure the absorption of rooms in the field is described in Test Method E2235 . 1.3 This test method includes information on laboratory accreditation (see Annex A1 ), asymmetrical screens (see Annex A2 ), and reverberation room qualification (see Annex A3 ). 1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.5 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. 1.6 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 Measurement of the sound absorption of a room is part of the procedure for other acoustical measurements, such as determining the sound power level of a noise source or the sound transmission loss of a partition. It is also used in certain calculations such as predicting the sound pressure level in a room when the sound power level of a noise source in the room is known. 5.2 The sound absorption coefficient of a surface is a property of the material composing the surface. It is ideally defined as the fraction of the randomly incident sound power absorbed by the surface, but in this test method it is operationally defined in 4.2 . The relationship between the theoretically defined and the operationally measured coefficients is under continuing study. 5.3 Diffraction effects 4 usually cause the apparent area of a specimen to be greater than its geometrical area, thereby increasing the coefficients measured according to this test method. When the test specimen is highly absorptive, these values may exceed unity. 5.4 The coefficients measured by this test method should be used with caution because not only are the areas encountered in practical usage usually larger than the test specimen, but also the sound field is rarely diffuse. In the laboratory, measurements must be made under reproducible conditions, but in practical usage the conditions that determine the effective absorption are often unpredictable. Regardless of the differences and the necessity for judgment, coefficients measured by this test method have been used successfully by architects and consultants in the acoustical design of architectural spaces. 5.5 Field Measurements— When sound absorption measurements are made in a building in which the size and shape of the room are not under the operator's control, the approximation to a diffuse sound field is not likely to be very close. This matter should be considered when assessing the accuracy of measurements made under field conditions. (See Test Method E2235 for a procedure that can be used in the field with less sophisticated instrumentation.)