My neighbor just installed two air conditioning units, a pool heater, and two pumps on a cement slab four feet from a six foot fence than runs along our property line. The noise is loud enough to be troublesome and I doubt that our neighbors will cooperate so I think the fence is my only solution. It is a solid fence but has vertical one by sixes with 1/4 inch gaps. The good side is to the neighbor so I can side my side. If I use tongue in groove PT I could make my side solid. Any other suggestions? There would be a couple inches of free space between the sides. What could I fill it with? Also How far would I have to go with it. The equipment is about 8 feet long and the fence goes 60 feet. Would plants help and if so what kind? I really don't have to kill the sound, just knock it back some. So any percentage estimates for noise reduction would be useful.