The lower frequency reports, like from a 20 gauge using field loads, fired from your 26" barrel aren't too bad, but when someone else fires to your side and slightly back, it's much more of a problem.
I've found that very slow-burning powders in, say a .30-06 make a much louder report than others. For instance, I switched from IMR 4350 to IMR 4064 and was amazed at the difference in report and muzzle flash.
The worst for me was firing a .357 magnum handgun, braced against a tree. After three shots, my ears rang for three days. Firing my 7 1/2", 44 magnum, using IMR 4227 instead of IMR 2400 was much more pleasant. The difference in frequency made it more comfortable than any of my .357 mag loads.
Once, I fired my .270 Win with the muzzle next to a plywood trail sign on a post and the reflected sound was horrible!! That's something to consider as well. Noise under the roof at the range is also much worse than in the woods or in open areas.