Bought a house and moved in, I decided to turn one of the basement rooms into a home cinema. Turns out the room has a lot of echo, way too much to enjoy a movie.
The walls are stone (plastered bricks), the floor is tiles, so all surfaces are hard. As it's a basement room, it only has two very small windows and one door. The room is fairly long (about 4m by 11m). So that is a lot of hard surface to echo from. And I don't have unlimited money left over.
What's a pragmatic way of reducing the echo in this room? Since it's a dedicated cinema room, I'm happy with putting panels on the walls and ceiling, or do whatever else wouldn't work for a living room - as long as it is reasonably cheap even given the size. That excludes most of the special noise-reduction panels that I've found online.
I've already hanged about 2m of curtains on the side walls near the screen, put some empty boxes around the room and some leftover carpet on the floor - to little effect. It probably covers too little of the total surface area.
Would putting styrofoam plates have an appreciable effect? Do I have to cover the ceiling? Is there something I can do with the placement of the speakers (5.1 system) ?