According to the 49/2002 EC directive noise mapping of large industrial plants is now obligatory. The biggest problem in calculating industrial plant noise is in deciding the best way to model all the separate noise sources, which are usually present. When aggregated together, the separate contributions from a large number of smaller sources can be as or more significant than the effect of the one or two major noise sources present. On the other hand, the additional cost and complexity of measuring each separate noise source separately is not always justified. This paper reports a method for calculating the effect of multiple noise sources (such as pipes, boilers, turbines, generators, transformers, etc) in a power plant. Measurements were used to justify the input data of the noise map so as to be able to calculate the overall effect of each noise source separately. Used in conjunction with standard noise mapping procedures, it is then possible to identify the number of separate noise sources, which must be included to obtain an accurate map. In many cases, it is possible to lump together various categories of separate noise sources without compromising the overall accuracy. The combined results from measurements and calculations were used for noise reduction planning. We present the estimated effect of various noise reduction methods based on noise mapping conforming to the requirements of the EC directive, together with measurements showing the degree of noise attenuation actually achieved.
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