This may open up a marketing opportunity for someone. A batting helmet that also doubles as a sound dampener. Close off the ear holes, make it fit tighter and there ya go.
I have had to use ear plugs and ear muffs in different situations, I can’t stand to wear them. I couldn’t imagine trying to wear them and play a sport.
Stats try to score a game wearing ear protection and see if it helps with your concentration. I guess studies ( I am putting a disclaimer here that I did not and will not search for any) have shown that when one sense is taken away other senses become stronger, but would putting in ear protection in for an at bat or pitching for an inning help performance, I don’t know.
I’d vote for handing out muzzles to the crowd as they enter the stadium, it might even increase attendance at many games. At least I would entertain sitting in the bleachers as opposed to standing out in left field!