声学

[中文适用范围]： 本文件规定了一种计算室外传播过程中声音衰减的工程方法，以便预测距离各种声源一定距离的环境噪声水平。该方法预测在有利于已知声源传播的气象条件下等效连续 A 加权声压级（如 ISO 1996 系列中所述）。这些条件适用于顺风传播，或者等效地，在发展良好的中等地面温度逆温条件下传播，例如在晴朗、平静的夜晚。本文件未涵盖广阔水面上的逆温条件，这种逆温条件可能导致声压级高于本文件预测值（例如，参见参考文献 [11] 和 [12]）。该方法还预测 ISO 1996-1 各种气象条件下规定的长期平均 A 加权声压级。已提供指导，根据 ISO 1996-1:2016，3.2.1 和 3.2.2 中规定的参考或长期时间间隔的相关角风分布，得出气象校正。参考时间间隔的示例是白天、夜晚或声压级值最大的夜晚。长期时间间隔，在此时间间隔内，对一系列参考时间间隔的声音进行平均或评估，代表一年中相当一部分（例如 3 个月、6 个月或 1 年）。本文件中规定的方法具体包括倍频带算法（标称中频带频率为 63 Hz 至 8 kHz），用于计算来自点声源或点声源组合的声音衰减。声源（或多个声源）可以是移动的，也可以是静止的。算法中提供了以下物理效应的具体术语： — 几何发散； — 大气吸收； — 地面效应； — 表面反射； — 障碍物遮挡。附件 A 提供了有关通过树叶、工业场地和房屋传播的更多信息。附件 B 包含了支持工业场地声音预测的烟囱指向性。附件 C 给出了如何根据当地风气候学确定远距离气象校正 C0 的示例。附件 D 总结了过去几十年来如何预测风力涡轮机引起的声压级的经验。该方法在实践中适用于各种各样的噪声源和环境。它直接或间接地适用于大多数与道路或铁路交通、工业噪声源、建筑活动和许多其他地面噪声源有关的情况。它不适用于飞行中的飞机发出的声音，也不适用于采矿、军事或类似作业产生的爆炸波。要应用本文件的方法，需要了解与源和环境的几何形状、地面特性以及以与传播相关的方向的倍频程声功率级表示的源强度有关的几个参数。如果只知道声源的 A 加权声功率级，则可以使用 500 Hz 的衰减项来估计最终的衰减。第 9 条描述了该方法的准确性及其在实践中的使用限制。 [外文原描述]： This document specifies an engineering method for calculating the attenuation of sound during propagation outdoors in order to predict the levels of environmental noise at a distance from a variety of sources. The method predicts the equivalent continuous A-weighted sound pressure level (as described in ISO 1996-series) under meteorological conditions favourable to propagation from sources of known sound emission. These conditions are for downwind propagation or, equivalently, propagation under a well-developed moderate ground‑based temperature inversion, such as commonly occurs in clear, calm nights. Inversion conditions over extended water surfaces are not covered and may result in higher sound pressure levels than predicted from this document (see e.g. References [11] and [12]). The method also predicts a long-term average A‑weighted sound pressure level as specified in ISO 1996-1 and ISO 1996-2. The long-term average A‑weighted sound pressure level encompasses levels for a wide variety of meteorological conditions. Guidance has been provided to derive a meteorological correction based on the angular wind distribution relevant for the reference or long-term time interval as specified in ISO 1996-1:2016, 3.2.1 and 3.2.2. Examples for reference time intervals are day, night, or the hour of the night with the largest value of the sound pressure level. Long-term time intervals over which the sound of a series of reference time intervals is averaged or assessed representing a significant fraction of a year (e.g. 3 months, 6 months or 1 year). The method specified in this document consists specifically of octave band algorithms (with nominal mid-band frequencies from 63 Hz to 8 kHz) for calculating the attenuation of sound which originates from a point sound source, or an assembly of point sources. The source (or sources) may be moving or stationary. Specific terms are provided in the algorithms for the following physical effects: — geometrical divergence; — atmospheric absorption; — ground effect; — reflection from surfaces; — screening by obstacles. Additional information concerning propagation through foliage, industrial sites and housing is given in Annex A. The directivity of chimney-stacks to support the sound predictions for industrial sites has been included with Annex B. An example how the far-distance meteorological correction C 0 can be determined from the local wind-climatology is given in Annex C. Experiences of the last decades how to predict the sound pressure levels caused by wind turbines is summarized in Annex D. The method is applicable in practice to a great variety of noise sources and environments. It is applicable, directly, or indirectly, to most situations concerning road or rail traffic, industrial noise sources, construction activities, and many other ground-based noise sources. It does not apply to sound from aircraft in flight, or to blast waves from mining, military, or similar operations. To apply the method of this document, several parameters need to be known with respect to the geometry of the source and of the environment, the ground surface characteristics, and the source strength in terms of octave band sound power levels for directions relevant to the propagation. If only A‑weighted sound power levels of the sources are known, the attenuation terms for 500 Hz may be used to estimate the resulting attenuation. The accuracy of the method and the limitations to its use in practice are described in Clause 9.