I gave some thought to this last night and realized a picture is worth a thousand words. Some opinions vary, but this should simplify reducing track noise. Remember, solid rail is quieter than hollow rail as hollow rail acts as a resonator, so Gargraves and especially "toy train" track will make more noise. Glued ballast can hold the track in place but the gluing process (water, etc) can permeate the sound board unless it's pre-sealed against moisture. Sound travels better/faster/farther through dense media, so the key is to isolate the vibrations using less dense media.
