Generac Generator Enclosure to reduce sound

[ggunn]

In general, the sound level drops 6dB every time the distance is doubled. So technically at 46 ft. the gen unit sound level should be reduced by 6dB.

Compared to the dB level at 23 feet, OK (and of course it's theoretical, not taking into account the context of nearby acoustically reflective and absorptive surfaces), but at what distance from the generator is the 55dB requirement measured?

If the generator is located against a brick wall, acoustically treating that wall could possibly reduce the SPL at the property line.