I don't agree with Newbee. Flutter echo makes a difference anywhere in the room, since sound reflects from all of the surfaces and combines into what reaches your ears.
The source of flutter echo is usually easy to locate. If you walk carefully around clapping, you may pinpoint the exact place where it begins and ends. Open hallways, or reflections between ceiling edges and untreated hardwood floors are typical sources. You can check floor-ceiling bounces by putting thick towels or rugs down on the floor and see if that kills it.
In my setup, I've found that foams and absorbers on the ceiling can do too much absorbing. Diffusors at either reflection point work equally well and, in fact, better than absorbers. So you might experiment with RPG or other diffusors, as well as rugs, bookcases and the like when you identify the source.
The source of flutter echo is usually easy to locate. If you walk carefully around clapping, you may pinpoint the exact place where it begins and ends. Open hallways, or reflections between ceiling edges and untreated hardwood floors are typical sources. You can check floor-ceiling bounces by putting thick towels or rugs down on the floor and see if that kills it.
In my setup, I've found that foams and absorbers on the ceiling can do too much absorbing. Diffusors at either reflection point work equally well and, in fact, better than absorbers. So you might experiment with RPG or other diffusors, as well as rugs, bookcases and the like when you identify the source.