No doubt distance is your friend when it comes to noise and as the distance increase it become more so. Which should be an obvious. Distance is why I can’t hear the piper over your house from mine. What that distance is would be relative to the original decibels.
As far as your energy theory, the energy or noise as you define it, coming out of the muzzle is the same braked or not.
Read on:
https://precisionrifleblog.com/2015/08/07/muzzle-brakes-sound-test/At some point you do get far enough away. However, that distance changes with the cartridge. Think.243W
vs .50BMG.
Still interested in your testing equipment.
Addition: question answered, thanks.
Addition 2: I have two gun clubs approximately 5 miles away. When conditions are right you can hear the cadence of them shooting trap.
