I can't tell you about any of the other buses. But I can tell you about mine. David was partially deaf from years of using loud saws, etc in building houses and making cabinets. So he turned up the TV pretty loud. You could not hear the TV going too much from outside. I only heard it once I got up real close (like about 5-6 ft away). Can't hear my residential washing machine from outside either. The road noise is pretty muffled except in the bedroom which is backed up to a busy highway (about 10 ft from roadside curb). We kept the original single pane glass bus windows. I attribute this sound reduction to the way the walls are constructed in our conversion...
Outside to inside:
Original steel siding
2" (nominal) Original fiberglass batt insulation
Original steel interior wall covering
1" R-Tech EPS - Expanded PolyStyrene (R 3.85@75F) (used 1X2 & 1X3 furring strips shimmed out to 1" as a thermal break and as "nailers")
7mm thick Traffic Master Laminate Flooring (attached to the furring strip nailers with screws)