Our hearing ability is a complex process. Many years ago I bought a pair of sound dampening ear plugs for use while duck hunting. The shooting was ruining my hearing, but I wanted to hear what was going on around me while hunting. The volume of the plugs could be adjusted like a hearing aid, but they electronically clipped off loud noises within milli-seconds. They were also custom molded to my own ears. I balked at the high price until my half-deaf hunting buddy said, "Yeah, you better save that $750 'cause you're going to need it for these $4,000 hearing aids." I bought them that week and still use them duck hunting to this day. I believe they were made by a company called Electronic Shooting Products or ESP.
I also bow hunt for deer, so I tried them for the amplification feature. It seemed harder to pinpoint the location of a sound. It also amplified every sound you normally tune out, and the world is a very noisy place. Noises that are loud, but under the threshold of the dampening, can be quite annoying. Think of cicada's buzzing, dried leaves constantly rustling in the breeze, a crow calling. I could do a much better job of hearing what I wanted to hear without the amplification (even high quality amplification). I don't know if they're still around, but I would highly recommend them for hearing protection while hunting. Not so much for amplification.
