Hmmmm... lets see...
Case side on: Sounds like someone in the next room with one of those big honkin' hair dryers, doin' their hair.
Case side off: Sounds like someone standin' behind you, doin' YOUR hair.. ???
Yeah, they're kinda loud. The first night I plugged mine in, my wife was watching TV down the hall in the living room. She could hear the Delta over the TV!! I went wandering thru, headed for the kitchen at one point, and she looked at me and asked, "What the heck are you doin' in there?"
Um...yeah, they're kinda loud...tee-hee-hee Cool the Hammers of Hades, though. =)