These are plugs with "flat attenuation" - the Etymotics custom-molded Musicians Earplugs are the classic ones (you go to an audiologist to make a mold) - they actually have a variety of attenuators, including a 25dB one (for drummers). I used a 15dB set for years and they were responsible for saving a lot of my hearing over countless shows, etc. Custom molds will lose their fit (your ear shape changes over time?) and when I was looking to replace them, I tested a bunch of the new plugs around, I found Earasers to be fit and work as well as my customs, at a much lower price (about $40).

In loud environments, I've definitely found the same phenomena, where it was much easier to understand people talking w/ the dB cut. I never thought this was a disorder, but rather a natural result of lowering the sound floor that made voices easier to pick up/distinguish?