I'm a newer hunter, and I assume this goes without saying to the people who have been doing it longer, but it merits repeating anyhow -
Every honest opportunity on an animal I've had so far, has given me ample time to place plugs in my ears. Honestly, its amazing how long some of them will wait to make a move, while I'm trying to rush through prepping for the shot.
You have much more time than you think you have. Your hearing is worth it. If the "opportunity" won't allow you time to put in plugs, lets be honest, should you really be taking the shot anyhow? The answer is probably not.
edit - I use the kind that hang around your neck.
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They're unobtrusive. I put them on when I leave the truck. Take them off at the end of the day when I'm going to sleep. You quickly forget that they're there - and when you need them its easy to toss them in.