Given that the air dumped is the same, then how do different dump valves achieve a massive increase in volume?

I have the forge VTA dump valve running on the soft spring, how much louder is the loudest dump valve?

 

With the same vented air volume the way dumpvalve noise differs is down to the way the air is vented.

This being vent size, shape etc.

some of the jap spec bov's have trumpets to achieve louder blow off's