Jim you are going to get sound regardless of glues used. The foam does not absorb sound. it actually transmits as the sound is reflected. I would think it is because of the density of the materials used...You can drive a screw into it, and it stays put..that is density'..

[:-headphones] get a set..

Jim, this is very subjective when it comes to sound.

I used Liquid nails for foam to glue the #250 formular pink foam to my wood frame of 1/2” thick x 21/2” 5 ply ripped from 4x8 sheets. I used 16” centers and no part of the railroad is wider than 24”. Every piece of wood that touch’s the foam has Liquid nails on it. I glued the cork road bed down with DAP’s Alex Plus and glued the tie strips using Elmer’s glue All white. I don’t have a drumming effect or a noise issue, but I run sound in all locomotives at about 15% of volume.

I have read others have a terrible sound issue. I believe they left dry some foam and frame touching surfaces but all claim they glued everything. Good luck.

Tom