Noise is defined as "sound that lacks agreeable musical quality or is noticeably loud, harsh, or discordant" or "results from irregular vibrations and produces an unpleasant sound." Although there is no exact and universally accepted point at which sound is perceived as noise, potential hearing damage due to noise is an accepted and recognized occupational hazard in industry. The extent of damage depends on the length of time exposed, the intensity, and the exact nature of the noise. Eventual hearing impairment is the most obvious damage caused by high industrial noise levels. There are many others. Occupational noise is linked to increased nervousness, irritability, and anxiety. New research indicates a possible additional relationship to heart disease, cardiovascular disfunction, and certain gastrointestinal, endrocrine and metabolic disorders. Job-related noise also makes work more difficult by impeding communications. Noise causes productivity to decrease and on-the-job safety to suffer. OSHA Regulations The Occupational Safety and Health Administration (OSHA) sets the standards for occupational noise exposure. These standards must govern the maximum levels of industrial noise an employee may be exposed to and they explain what action must be taken if these levels are excessive. How to Intrepret Noise Levels Noise levels are measured and reported in decibels. However, the decibel system can be confusing because it is based on a logarithmic scale. For example, 110 dB noise is not 10 percent greater than a 100 dB noise level, it actually represents 10 times the accoustical energy. For this reason, a small increase or decrease in the sound pressure level (measured in decibels) has a very significant effect on the noise intensity. A drop of just three decibels means the sound pressure level has been cut in half. Source Control Noise radiates from a source. The most desirable approach to noise control is to reduce noise at its source. At the source, the addition of accoustical material can significantly reduce the noise level. Foam, mineral wool, and fiberglass are effective sound absorbers because their porous structure soaks up sound. These materials absorb noise by dissipating the sonic energy into small amounts of heat.
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