I was setting cabinets in a recording studio and they were installing two types of sound barrier, one that looked like straw panels and the other was a roll of foam. The installers said to think of it as a roll of paper towels and a spill, it absorbs sound the same way. They gave a roll to me and I took it home and used push pins to hold it up under the layout. It took about 30 minutes. When I need to access something I just pull the pins and roll it back. I regularly remove parts to wire buildings. My layout consists of 3/8” birch 8 ply, 1/2 inch homasote on the table and homasote roadbed. I already had carpet squares under the layout and theater style drapes so I didn’t expect a huge change, but the foam made a noticeable difference. Train noise doesn’t bother me, but it is nice being able to hear the television when the trains are running. During the Holidays I like to watch old Christmas movies while playing with the trains and I don’t have to turn the volume up really loud to hear it.