This may be neither here nor there . . .
Between riding and shooting and being around jet airplanes (you know, the sound of freedom) for many years, I keep looking for something better -- per the OP. I finally decided to go for custom ear plugs, and wouldn't you know (as Rosanne Rosanna Danna used to say on SNL), "It's always somethin'"
So I went to the audiologist, and she put the goop in my ears, and four weeks later I returned to pick up the new ear plugs, just pleased as punch -- now I was in the club.
First couple of times I rode . . . at first -- noise attentuation was good, but **** . . . my ears hurt.
"How could that be ?" I asked myself.
Turns out, I'm one of those big-ears guys (kids at school used to flick them when we were standing outside in the winter waiting for the doors to open -- and numb with cold didn't feel anything -- but the pain I still remember from once inside and they came to room temperature). I never noticed before, when I put on the helmet, it forces my ears back against my head, and that put pressure against the ear plugs. A guy at work suggested, "Now you need two sets. You need to go back to her and make another set with your ears held back."
It's always somethin'
So they're a big improvement for shooting. I'm still looking for under the helmet.