Noise, or unwanted sound, is a pervasive occupational health problem. Exposure to high levels of noise can cause hearing loss. The extent of damage depends primarily on the intensity of the noise and the duration of the exposure. Noise-induced hearing loss can be temporary or permanent. Temporary hearing loss results from short-term exposure to noise, with normal hearing returning after period of rest. Generally, prolonged exposure to high noise levels over a period of time can gradually cause permanent damage.