A simple solution would be to add a loading screen, on a front layer set to white and background visible, in each layout.
In a separate event sheet, store the global sound level in a variable and then set it to -80dB to cut the sound.
Add in this event sheet a function "EndLoading", that will restore the sound level, and hide the front white layer (or image you put in)
Include this sheet in every principal event sheet of your layouts, and add a call to the function "EndLoading" once you handled the change of layout on Load of a savestate.