声学 机器和设备发射的噪声 在一个反射面上方可忽略环境修正的近似自由场测定工作位置和其他指定位置的发射声压级
Acoustics—Noise emitted by machinery and equipment—Determination of emission sound pressure levels at a work station and at other specified positions in an essentially free field over a reflecting plane with negligible environmental corrections