HaloMods "Classic" Read-only Archive

I have an Idea on how to do this but I need to know if anyone could tell me how to have the echo noise in a map Such as the way it does in metroid tunnel 2. I'm making a dome shaped mach mod right now and really need to know how to pretty much complete my mod

Thanks in advance

Sound environment

I understand that part but like where could I find the effect to put into my map?

snde tag link it to the scnr i think...