it gets pretty loud in the cab, i bought ear protection.
You should use ear protection when using a snowblower even if you don't have a cab.
I use ear plugs and ear muffs at the same time. From what I've read the plugs give a couple of db more protection. The ear muffs keep my ears a bit warmer. I use the setup I got for using a chainsaw, hard hat, mesh face sheild and ear muffs attached to the helmet. I don't use the shield that often when I need it I just flip it down.