My DS5 has major sensory issues in regards to sounds. Even the movie theater is too loud for him.
I went to Home Depot and bought headphones (earmuffs) that construction workers use when they work with loud machinery. DS has a rather large noggin.... so at their smallest size they worked perfectly for him.
We watched fireworks, went to shows and even lots of rides without any melt downs. We had tried other earplugs.... but nothing worked as well for us as these.