Reply to "I prefer scale distance running sounds!"

I would suggest two experiments to help identify the problem:

  a)  A section of track where the ballast between the rails is not glued, but the shoulder ballast is.

  b)  Another section where the ballast is not glued at all.

Which particular S. Express ballast are you using [ part number ] ?

Edited to add:  What brand of flex track are you using on the ballasted section ?

SZ       [ 2R'er w/ ballasted flex track, but who has hearing issues, even w/ two h. aids ]