Noise-induced hearing loss (NIHL) is the most common occupational illness in the United States, with 30 million workers exposed to excessive noise levels every day. Of particular concern is the mining industry; which has the highest prevalence of hazardous noise exposure of any major industry sector and is second only to the railroad industry in prevalence of workers reporting hearing difficulty. This document is for operators, safety personnel, and mechanics in the mining industry who are not specialists in noise control engineering or acoustics. Evaluations of successful and unsuccessful attempts at controlling noise on several large, underground metal mining machines are detailed to illustrate the basic principles of noise control. Once personnel understand the guidelines and principles of noise control, they will be able to evaluate the extent of a noise problem; determine the best approach to the problem; and apply the most appropriate solution. Because of the insidious nature of NIHL, it can go unnoticed until a considerable loss of hearing has occurred. In some cases, diagnosis is delayed because an exposed individual claims to have become accustomed to the noise. In reality, that person may have already suffered irreversible hearing loss.