Check surefire. From what I understand they will do exactly what you are asking. I have been wanting to grab some myself due to the cheap price of them
I've had good luck with the surefire sonic ep3 or 4's. I forgot which one i prefer (but it's the one with the 3 sections to the ear canal not 2). There's a little plug, where if you keep it unplugged you can still hear some, but is lowers noise enough to shoot outdoors, but if you plug it, you can shoot outdoors or indoors.
So with the EP4 you can hear a normal conversation if they aren't plugged but won't harm your ear when you fire a weapon? Just making sure I order the right ones
Personally, I prefer a pair of the surefire ep7's the ones with the compressible foam tips) over any other ear protection. They are a bit pricey compared to some other foam plugs, but the are worth it for the comfort and sound reduction.
The EP 7 is the best protection, the foam doesn't last a long time tho, and their not really cheap, that's the only draw back. Ear muffs get in the way shooting a rifle so surefire it is, they are comfortable! I also use the 4's doing carpenter work, their perfect for that, they need to be replaced every month or so if their used every day
Surefire EP4 work well for me, even in an indoor range.
I usually use the 33 db foam plugs, but you can't hear anything with them on.
Took a SD class on an outdoor range a few days ago and used the Surefire earplugs - worked great.
Not perfect, but very pleased with them - a little over $ 15.00 on Amazon.