Farmer 1,
I agree that the main rotor "vortex interference" causes most of the oncoming noise in the big machines. I spent many years as a loader driver for AG ops & used to have a quick nap on top of the water tank between loads on occasion. The noise of the 206 tail rotor when the machine was on its way back for another load would wake me up in time to start the pump & get the fuel hose before the machine even came into view!!