GB/T 17247.2-1998 in English

《GB/T 17247.2-1998声学 户外声传播的衰减 第2部分:一般计算方法》由TC17（全国声学标准化技术委员会）归口，主管部门为中国科学院。
本标准规定了计算户外声传播衰减的工程法，以预测各种类型声源在远处所形成的环境噪声级。此方法可预测已知噪声发射声源在有利于传播的气象条件下的等效连续A声级。

Scope

This standard specifies the engineering method for calculating the attenuation of outdoor sound propagation, in order to predict the environmental noise level caused by various types of sound sources at a distance. This method predicts the equivalent continuous A sound level (described in ISO 1996) Parts 1 to 3) of known noise emitting sources under favorable meteorological conditions for propagation. These conditions are for downwind propagation as specified in ISO 1996-2:1987 and 5.4.3.3, or equivalently for propagation at moderate ground-based temperature inversions that have stabilized and often occur at night. Temperature inversion conditions on the water surface are not included, in which case the sound pressure level predicted by this standard may be higher. This method can also pre-cover the long-term average A sound level specified in ISO1996-1 and ISO1996-2. The long-term average A sound level includes the sound level of various meteorological conditions. The method specified in this standard includes, inter alia, an octave-band algorithm (using a nominal band center frequency of 63 Hz to 8 kHz) to calculate the sound attenuation emanating from a point source or group of point sources, which may be moving or stationary, The items specified in the algorithm have the following physical effects: - geometric divergence; - atmospheric absorption; - ground effects; - surface reflection; Additional information can be found in Appendix A. In fact, this method can be applied to a wide variety of noise sources and noise environments. It can be applied directly or indirectly to large noise sources such as road surfaces, rail traffic, industrial noise sources, building construction activities, and many other ground-based noise sources. Mostly, but it cannot be applied to aircraft in flight, or shock waves for mining, military or similar operations. To apply this standard, several parameters must be known, corresponding to the geometry of the source and environment, the characteristics of the ground surface and the intensity of the source in terms of octave-band sound power levels consistent with the direction of propagation. Note: If only the A-weighted sound power level is known, the attenuation at 500 Hz can be used to estimate the final attenuation. The accuracy of the method and its limitations in practical applications are described in Chapter 9.