Declared noise emission values of machinery and equipment based on determination of the combined standard deviation

The declared noise emission values determined according to the internationa l standards seem to depend on the frequency distribution of the machinery a nd equipment. In this article the declared values have been estimated in a new way for a single machine and for a batch of machines. The confidence in tervals of a normal distribution used in evaluation have been obtained by c alculating combined standard deviation values from standard deviation value s of single frequency bands (given in standards) and (1) the level informat ion of the measured frequency bands or (2) measured A- and C-weighted level information. It is shown that it is possible to find an upper limit for th e confidence interval. The declared values found in this study are equal to the values based on the common ISO method. (C) 1998 Elsevier Science Ltd. All rights reserved.