Your earplugs ar the regular set. Go kill Yian garugas and break their heads for a chance at the ears... you can make gems that work to upgrade your Rathalos set's earplug skill to high grade ear plugs. That in turn will work if you're facing diablos, Garuga etc.
Monsters that require high grade ear plugs are as follows:
Garuga
Gravios(includes all sub species)
Diablos(*same as above)
Monoblos(actually he's a sub of a diablos.. heck. the white monoblos too)
Khezu(and the red one)
Lao shan lung(and azure)
Fatalis
I believe I'm missing something, at any rate, you can block a scream. so that's solution 2.