What is the standard level of noise for a typical generator? The answer is 85db within a 1 meter radius.
The noise level is normally dependent upon the quality of insulation, type of enclosure and engine type of a generator.
In a cinema, the typical insulation used is known as “rock wool”. It is also used in roofs in a home to insulate from heat and rain noise. While it is a good material to use, it is also easily burnt when exposed to extreme heat. Therefore this type of material is not recommended.
If cost is an issue, one could use sponge to insulate noise and this is a good option because there are many types of sponges with various densities.
Type of enclosure
Genset enclosures use steel for the most part of its cover. The question is how thick is this steel plate enclosure? The logic is, the thicker it is, the more insulation it can provide.
Engine type of a generator
The japanese engines tend to be more quiet, compared to the british and american engines. This is because the japanese focus on efficiency of an engine while the rest puts emphasis on power output.