HELP! Cork Roadbed *Increasing* Train Noise

Hey guys, I've just begun laying the roadbed and trackwork for a small HO scale switching layout, and although not new to the hobby (mostly been weathering and detailing rolling stock) - this is my first layout in a long time. Here is the strange dillema I am facing: My layout is built atop 2" blue foam boards, and although sufficient at reducing train noise, I decided I wanted a trace of roadbed for the mainline. I purchased some N scale cork roadbed strips, and before permanently plac