The Bureau of Mines conducted an environmental noise survey to determine the noise levels to which underground coal mine employees are exposed, to evaluate noise survey techniques and equipment, and to compare noise exposures using two criteria, walsh-healey and chaba, for determining allowable exposures that were not under consideration for the Federal Coal Mine Health and Safety Act of 1969. Time study techniques and Bureau-approved standard sound level meters were employed. The shift exposures of 20 percent of the miners studied were in excess of the safe standards established by both criteria. The shift exposures calculated using the walsh- healey criteria were greater than those calculated using the chaba criteria owing to the intermittent nature of the exposure. Ultimately the chaba criteria were rejected, and the walsh-healey criteria were adopted.