I imagine the measurement is something like "perception of sound to the human ear". A rock concert is generally very loud and whether you're 5 feet back or 30 feet back from the stage won't make a huge difference

[–] jsomae@lemmy.ml 6 points 6 months ago

A rock concert emanating from a point will sound considerably louder at 5 feet vs 30 feet and will make just as much of a difference as 50 feet vs 300.

Of course, accoustics in a concert hall are designed to minimize this difference. Doesn't explain jet fighters though.