This may not transfer to wood aircraft however I bought sound deadening material from a company called E.A.R it was a sticky foam with an aluminum back it stuck on like tape .I did this on my Cessna 182 and got more than one comment on how Quiet my airplane was . I put it in the center of two bay aft of the cockpit and added a thick paper partition aft of that with cut outs for control cables .After I did that I started finding small little air leaks. The one thing that made the biggest change that was immediately noticeable was adding wind lace around the doors. Wind lace looks like a piece of rope with a fabric flange on one side that you can bend around curves to fit the opening.
You may want to try this to get a quieter cockpit it sure worked good in my Cessna. Jim B K.R.-2 S Wichita
