采掘工人在作业岗位上按露采工艺操作钻孔机、履带式拖拉机、挖掘机和卡车时,如果使用的是未加改进的设备,其噪声平均可达100～115dB(A)。机械装配式冲击钻孔机的噪声最大,当钻机的钻头钻入岩石时,噪声可达115dB(A)。在这种噪声环境中允许暴露的时问,随国家的不同而异。大多数工业围家都要求限 Excavators operate up to 100-115 dB (A) of noise with unmodified equipment when operating drilling machines, track-type tractors, excavators and trucks in open-pit operations at their job sites. Mechanical assembled percussion drills produce the highest noise, with noise up to 115 dB (A) when the drill bit drills into the rock. The time allowed for exposure in this noisy environment varies from country to country. Most industrial enclaves have limits