I set up my 9x16 layout on 3/4" plywood board with 2" foam board on top. The Atlas track I use is mounted on cork roadbed.
The loco sounds are set so there loud as it passes, you, but you can still hear the freight cars wheels clickity clack plus the sounds produced by my sound cars, as the power moves away. More prototypical I think.
I don't like the drumming sound produced when there's no insulation other than cork roadbed.