[Distribution of under-pit noise of coal mining]

Noise distribution of a medium size coal mine was studied. There were 17 kinds of machine noise sources with an additional noise due firing of the gun. 449 sets of machine were distributed at the different canes and working places. Over 3000 workers were exposed to this noise. Noise intensity level of machines was 78.5-117 dB(A), of firing-a-gun 128 dB(A), the main working group Leq exceeded criterion (90 dB(A)) by 3-20 dB(A). Coal excavating machine had a high noise intensity level. These results may have reference value for investigation of noise pollution in the coal mines of China.