Screen sound transparency

Hi! Are front projection screens ( DaLite) sound trasparent or reflective? The reason I'm asking is: I want to install some foam diffusors on the wall in between my front speakers, right were the screen is supposed to be. So I'm wondering, if it makes sense to install screen on a top of diffusor panel, if it's reflective (the screen), it would defeat the purpose, wouldn't it? Thanks in advance.