Explosions are loud... very loud. Guns are loud too, but explosions are a lot louder.
Granted, this is space, but the comparisons should still be the same. It it hit you you would hear it anyway.
The fact that the Grand Culverin looks and sounds a LOT like a supernova is also a little unsportsmanlike... not terribly nice to our enemies, as cool as it is.
Hmm... I'm sure some of our members who have been in militaries can find something comparable via YouTube or somesuch and get across the difference.