Jackson really isn't fond of loud noises. He's generally fascinated by the object making the loud noise, but a high decibel level will drive him away every time. Recently, the object of his objection was the steam vacuum, which I will admit is pretty loud. This was our solution.
Yes, those are shooting range ear protection. Oddly, they're not available in toddler size.
Of course, if Jackson is the one making the loud noise, he's a-ok with it!