The harm to hearing from noisy workplaces can be difficult to detect. Tinnitus, or the constant high-pitched ringing in the ears that accompanies hearing loss, is usually experienced gradually. When the delicate structures that allow the ear to hear are damaged by repeated workplace incidents the ringing grows louder.
Hearing loss is an occupational illness common to many professions. Single noises can cause permanent hearing loss, especially if they are very loud. For example, firing a gun very close to the ear without hearing protection can cause temporary deafness and permanent harm to the hearing. Chronic noises, such as those found in a factory, can be even more harmful. In many cases the sufferer does not notice until the damage is beyond the point of healing.