A Study of Roof Warning Signals and the Use of Personal Hearing Protection in Underground Coal Mines.

摘要

Roof warning signals were studied in 18mines covering five coal seams. The results confirmed that roof talk must be interpreted for each individual mine after all other conditions are present that indicate danger of roof fall. Characteristics of roof talk pulses were studied to ascertain features used in interpretation. Roof talk pulse decay time was found to be typically 0.1to 0.5second depending on the dimensions of the entries. Time between roof talk pulses was found to correlate inversely with the degree of danger under certain conditions. Roof talk and machinery noise recordings obtained during this study were used for subjective tests of ear protectors in a simulated coal mine noise environment. These tests required a detailed interpretation of roof talk and yielded results with high statistical power. Results showed that the use of personal ear protectors in high noise levels did not degrade a miner's ability to discriminate speech and roof talk. A training course was developed to encourage coal miners to protect their hearing.