This is the 'Revolver' section...OP's question was with respect to Revolver Barrel lengths.
Pressures and or Volumes of Gas will be greatly smaller in Revolvers generally, than in Rifles or shotguns, of course.
I imagine most Ammunition for Revolvers assumes a mid length Barrel or a longer rather than shorter Barrel, far as powder type and Gas volume realized in relation to Bullet weight-resistence.
How this would co-relate to pressures at various lengths as the Bullet exists, could be all over the board...as would the report, even if all Reports seem 'loud'.
Black Powder in say 45 Colt Cartridges, gives a very good report in a Snubby or a long Barrel, and does so at what is likely 9 to 12 thousand PSI...far below usual smokeless pressures.
So pressure alone is not likely as much of an issue for decibles generated, as volume of Gas is of a given pressure.
Shorter Barrel Revolvers, the end of the Barrel is however much closer to one's Ears and face, than longer Barrels...and that has to make a little difference anyway! Whatever else is going on...