
Noise is unwanted sound and is an extensive occupational health problem. More than 30 million Americans are exposed to hazardous sound levels on a regular basis. Unlike many occupational hazards, exposures to harmful sound levels can also occur in recreational settings, homes, almost anywhere. Thus, the effects of a work exposure may be aggravated by other activities. To protect hearing, people should take measures to limit or minimize all exposures to harmful sound levels. This can be done by either controlling the sound source by reducing the level, by isolating the source or muffling the sound or by the use of personal protective equipment such as ear plugs or muffs. Hearing loss occurs in two basic ways: conductive and sensorineural. Conductive hearing loss is caused by a problem with a part of the outer or middle ear. A breakdown or obstruction interferes with sound transmission. This type of hearing loss is common and can often be reversed and hearing restored with appropriate treatment. Sensorineural hearing loss occurs from changes in the receptor hair cells in the inner ear or in the nerves carrying impulses to the brain. This type of hearing loss is usually permanent. Noise-induced hearing loss (NIHL) is sensorineural and is usually permanent. Fortunately, workplace NIHL can be reduced or even eliminated by the successful application of an occupational hearing loss prevention program.