Hi. I want to be compare the composite analysis and contact surface (freeze)

the example is above picture. And I want to check the ERP between 0~3000Hz. and I can get the follow this. (damping material density is 1856.07kg/m^3)
<?xml version="1.0" encoding="UTF-8"?>
<?xml version="1.0" encoding="UTF-8"?>
The blue line is contact surface(freeze) model, The black line is composite model.
why the blue line is more big value than black line abouy twice.
why the blue line is more big value than black line.
I want to know why two lines are different exactly.
Unable to find an attachment - read this blog