1.1 本试验方法包括气流阻力的测量，以及可用于吸声和消声的多孔材料的比气流阻力和气流电阻率的相关测量。材料涵盖了从厚板或毯子到薄垫子、织物、纸张和屏风的范围。当材料各向异性时，应规定沿试样不同轴进行测量。 1.2 本试验方法用于测量100至10范围内的比气流阻力值 000 mks射线（Pa·s/m），线性气流速度范围为0。 5. 毫米/秒 至50 毫米/秒，整个试样的压差范围为0.1 Pa至250 Pa.该线性气流速度范围的上限是通过大多数多孔材料的气流部分或完全从层流过渡到湍流的点。 1.3 本试验方法的实验室认证程序见 附录A1 . 1.4 以国际单位表示的数值视为标准值。本标准不包括其他计量单位。 1.4.1 表1 供用户转换为cgs单位。 cgs声欧姆 mks声欧姆（Pa·s/m 3. ) 10 5. cgs光线 mks射线（Pa·s/m） 10 cgs光线/厘米 mks射线/m（Pa·s/m 2. ) 10 3. cgs光线/英寸。 mks射线/m（Pa·s/m 2. ) 394 mks射线/英寸。 mks射线/m（Pa·s/m 2. ) 39.4 1.5 本标准并不旨在解决与其使用相关的所有安全问题（如有）。本标准的使用者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。 1.6 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 声学材料的特定气流阻力是决定其吸声和传声性能的特性之一。在产品开发、制造过程中的质量控制和规范目的中，测量特定气流阻力非常有用。 5.2 有效测量仅在层流区域进行，在该区域，除了随机测量误差外，气流阻力( R = 零件/部件 )是常量。当气流为湍流时，表观气流阻力随着体积速度的增加而增加，术语“气流阻力”不适用。 5.3 本试验方法测得的比气流阻力可能与试验方法中阻抗管法测得的比阻不同 E384（电子384） 有两个原因。在存在声音的情况下，多孔材料内的颗粒速度是交替的，而在本试验方法中，速度是恒定的，且仅在一个方向上。此外，多孔材料内部的颗粒速度与试样外部测得的线速度不同。

1.1 This test method covers the measurement of airflow resistance and the related measurements of specific airflow resistance and airflow resistivity of porous materials that can be used for the absorption and attenuation of sound. Materials cover a range from thick boards or blankets to thin mats, fabrics, papers, and screens. When the material is anisotropic, provision is made for measurements along different axes of the specimen. 1.2 This test method is designed for the measurement of values of specific airflow resistance ranging from 100 to 10 000 mks rayls (Pa·s/m) with linear airflow velocities ranging from 0.5 mm/s to 50 mm/s and pressure differences across the specimen ranging from 0.1 Pa to 250 Pa. The upper limit of this range of linear airflow velocities is a point at which the airflow through most porous materials is in partial or complete transition from laminar to turbulent flow. 1.3 A procedure for accrediting a laboratory for the purposes of this test method is given in Annex A1 . 1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.4.1 Table 1 is provided for user to convert into cgs units. cgs acoustic ohm mks acoustic ohm (Pa·s/m 3 ) 10 5 cgs rayl mks rayl (Pa·s/m) 10 cgs rayl/cm mks rayl/m (Pa·s/m 2 ) 10 3 cgs rayl/in. mks rayl/m (Pa·s/m 2 ) 394 mks rayl/in. mks rayl/m (Pa·s/m 2 ) 39.4 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 The specific airflow resistance of an acoustical material is one of the properties that determine its sound-absorptive and sound-transmitting properties. Measurement of specific airflow resistance is useful during product development, for quality control during manufacture, and for specification purposes. 5.2 Valid measurements are made only in the region of laminar airflow where, aside from random measurement errors, the airflow resistance ( R = P/U ) is constant. When the airflow is turbulent, the apparent airflow resistance increases with an increase of volume velocity and the term “airflow resistance” does not apply. 5.3 The specific airflow resistance measured by this test method may differ from the specific resistance measured by the impedance tube method in Test Method E384 for two reasons. In the presence of sound, the particle velocity inside a porous material is alternating while in this test method, the velocity is constant and in one direction only. Also, the particle velocity inside a porous material is not the same as the linear velocity measured outside the specimen.