Honestly, not too bad. It's a little loud, but when the fan runs, it drowns out the sound of the annoying little air compressor they give you, so I'm good with it. The buzzing of that thing is way more annoying than the sound of the blower.
I can still talk on the phone just fine with the fan running. I will say, that fan has some serious sucking power tho. It evacuates the fumes of acrylic JUST FINE. I have about 30 feet of piping for the exhaust to pump thru, and when I go outside to the vent, it actually moves the dead leaves around underneath it.
Wade