A good way to better protect your hearing from that Rotax twin inches from your ears beyond the standard shooters' earmuffs...

It's a favorite trick of mine at concerts and movies - a dry paper napkin cut into strips and rolled up to fit snug in ear canal then add a bunch of drops of water until they expand to seal out noise almost as if you were underwater.

I don't think you'd want to do huge altitude changes fast since it seals so well though. You can also soak the foam type earplugs with clean water, compress them for insertion and give them a few drops of water to soak up as conform to the ear canal...