During a recent hunt, my son commented that he noticed that I did not hear some of the squirrel rummagings and other woods noises, including his whispers.
I decided to try one of the up-scale hearing amplifier units. The one I tried two adjustments, one for volume and one for tone (Adjustment emphasizes low or higher frequency sounds). My unit also has an important volume limit feature. New unit cost to me was $137 via eBay auction (Retails: $190 to $265).

Results:
The unit gave excellent amplification, even at low and mid level volume settings. I actually had to reduce the volume setting to diminish the sound of mywalking and the breeze that was rustling the tree leaves.
With the volume anywhere above 1/4th, I could hear the rustle of every leaf my feet brushed against and every branch that brushed against my clothing.
Other than birds, I did not hear any other wildlife.
Am looking forward to using it extensively this fall.

Which one did you try?? Or which one do you have??

Bob,

Do they also amplify the sound of the wind and do they reduce the sound of gunfire?

My deafness was really bought home to me on my recent trip to Uganda when everyone else was commenting on the singing and drumming etc coming from the local village who were partying to celebrate our arrival and I couldn't hear a damn thing!

I'd have liked to have been able to hear that!