Thats why it is a "spread" area.
Anything that blocks LoE still blocks it though. You can also hear stuff behind a forcefield. It would still block the Holy Word.
Holy Word has a 40 foot radius. Surely you could hear it from farther then this. This tells us that there is more to the spell then just sound.
Note that I do not say how things "should" be done in the comic, just how things would be handled if the rules are taken to be granted.
A solid metal door completely blocking the corridor? Yeah, there is no way to spread arround this one and thus LoE would be blocked.