1.1 该分类涵盖了在三分之一倍频程频带内获得的实验室和现场声衰减测量的单数字声学额定值的计算方法。 1.2 单数字评级的名称由调用该分类的测试方法指定。 1.3 调用此分类的测试方法包括: 1.3.1 试验方法 E90 — 单数字额定值称为声音传输等级（STC）。 1.3.2 试验方法 E336页 — 单数额定值为噪声隔离等级（NIC）、归一化噪声隔离等级（NNIC）和视在声传输等级（ASTC）。 1.3.3 试验方法 E596 — 单数额定值称为噪声隔离等级（NIC）。 1.3.4 试验方法 E1414 — 单数字额定值称为上限衰减等级（CAC）。 1.4 以国际单位制表示的数值应视为标准值。本标准不包括其他计量单位。 1.5 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====== 4.1 这些单数字评级通常与语音、广播、电视以及办公室和建筑物中类似噪声源的声音传输的主观印象相关。这种分类方法不适用于频谱与上述声源显著不同的声源。这些噪声源包括机械、工业过程、保龄球联盟、电力变压器、乐器、许多音乐系统，以及机动车、飞机和火车等交通噪声。对于这些声源，准确评估声音传输需要在频带中进行详细分析。 分类中给出了建筑外墙构件的单数字声传输额定值 E1332 . 4.2 获得的单数额定值可用于比较在实验室条件下测试的隔墙或地板的潜在隔声性能（STC）或建筑物不同套房之间的实际隔声性能（NNIC、NIC）。由于侧面传输或施工误差，在建筑物中建造和测试的隔墙的额定值可能低于在实验室测试的隔墙的额定值。 注1: ISO 717-1:2020中描述的类似额定值程序提供了单位数隔声额定值，频率范围为100至3150 Hz，在各个频率下没有规定最大缺陷。对于大多数分区，两个额定值仅相差一个或两个点。

1.1 This classification covers methods of calculating single-number acoustical ratings for laboratory and field measurements of sound attenuation obtained in one-third octave bands. 1.2 The name given to the single-number rating is assigned by the test method that invokes this classification. 1.3 Test methods that invoke this classification include: 1.3.1 Test Method E90 — The single-number rating is called sound transmission class (STC). 1.3.2 Test Method E336 — Single number ratings are noise isolation class (NIC), normalized noise isolation class (NNIC), and apparent sound transmission class (ASTC). 1.3.3 Test Method E596 — The single-number rating is called noise isolation class (NIC). 1.3.4 Test Method E1414 — The single-number rating is called ceiling attenuation class (CAC). 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 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 ====== 4.1 These single-number ratings correlate in a general way with subjective impressions of sound transmission for speech, radio, television, and similar sources of noise in offices and buildings. This classification method is not appropriate for sound sources with spectra significantly different from those sources listed above. Such sources include machinery, industrial processes, bowling allies, power transformers, musical instruments, many music systems, and transportation noises such as motor vehicles, aircraft and trains. For these sources, accurate assessment of sound transmission requires a detailed analysis in frequency bands. A single-number sound transmission rating for building façade elements is given in Classification E1332 . 4.2 The single-number ratings obtained can be used to compare the potential sound insulation of partitions or floors tested in laboratory conditions (STC) or the actual sound isolation between different suites in buildings (NNIC, NIC). The rating for a partition built and tested in a building may be lower than that obtained for a partition tested in a laboratory because of flanking transmission or construction errors. Note 1: A similar rating procedure, described in ISO 717-1:2020, provides single figure sound insulation ratings with a frequency range that extends from 100 to 3150 Hz with no maximum deficiency specified at individual frequencies. For most partitions, the two ratings differ by only one or two points.