I mowed the grass for the first time this year, and I wore ear muffs rated at 25db of noise reduction, but after I had mowed about half the yard I could hear an increase in my tinnitus levels. The mower itself is fairly quite for a 4 cycle engine, and the vibrations coming up the handle didn't seem too bad. I am not sure what course of action to take, except maybe buy a 2 cycle Lawn Boy? Do they still make those in America? For what it's worth, I also edged the yard with a new Echo GT-225 gas trimmer. I have used this tool before a few times, but I don't recall it causing an increase in tinnitus. The GT-225 does not vibrate that bad. Edit: It has been 24 hours since I mowed the lawn / trimmed the edges, and my tinnitus is still a bit louder than usual. It is hard to fathom how these tools could cause so much issues.