Determine the pump sound level

Every rotating pump makes a noise. For sources of noise which are emitted in the open air, the sound level decreases by 6 dB (A) when the distance is doubled. The table shows the change in the noise level at different distances from the source.

For example, if we use a diesel driven pump as the source of the noise, this has an LWA value of 90. That means 90 dB (A) at 0 meters distance from the pumpset. If we then compare at a distance of 33 feet (10 meters) away from the pumpset, then the calculation is:

LWA-value:  90                    
Distance:  33 ft (10 meters)
Correction: -28,0 dB(A)

Noise level of the pumpset at 33 ft (10 meters): 62 dB(A)