ENVIRONMENTAL CONSIDERATIONS — dB(A)
Adding Additional Sound Sources
The noise level at a given location is the sum of the noise levels from all sources, including reflecting sources. For example, the noise level in a free field along side of two identical generator sets would be double the noise level of either set when both sets are running. A doubling of the noise level is represented as an increase of approximately 3 dB(A). In this case, if the noise level from either set is measured as 70 dB(A), the expected result of the combined generators would be 73 dB(A) when both units are running.
Figure 3 below estimates the noise level from multiple noise sources:
1.To find the difference in dB(A) between two of the sources (any pair), locate the dB(A) difference value on the horizontal scale as shown by the horizontal arrow. Add this value to the larger dB(A) value of the pair.
2.Repeat Step 1 between the value just determined and the next value. Keep repeating the process until all noise sources have been accounted for.
Figure 3. dB(A) Comparison Chart
Alternatively, the following formula can be used to add sound pressure levels measured in dB(A):
INDUSTRIAL GENERATOR SETS — APPLICATION & INSTALLATION MANUAL — REV. #4 (09/07/07) — PAGE 29