I bought the air revitalizer because I have dogs and a cat and I didn't want my house to smell like I have dogs and cats! When I bought it, I lived in a one story house. It worked great. (The only scent I've used is vanilla.) I don't think the sound is too loud, but I lived in a large house. When my house was for sale, I used it everyday and the house had a nice scent. I moved to a two story house, and didn't think it would scent as much of the house. I placed it in my entryway near the stairs and it scents most of the downstairs and upstairs from that location. I am impressed and very glad that I have it.