I use a lot of rugs in my flat to insulate and to reduce reverberations from my TV, hi-fi etc.

Sound reflections become worst in corners.
Without altering your room , you might be able to get away with adding foam V corners. They look pretty cool too.  they’re mostly used in sound recording studios. They’re shaped in a V and they wedge into the corners and run from ceiling to floor. You might cut down a lot on the echos, by taking out the hollow reverberations created from the millisecond pings that sound refections to in the corners. (imagine ping pong balls bouncing back and forth from wall to wall in the corners). It will keep sound reflections more of the orginal sound and cut them off from corner bouncing ,which causes them to alter tone. Rooms that are hard to hear in from bad echoes is because the echos are a varying degree of different pitches in tone and note , they then all mix and overlap to create a dischord spectrum of noises , and then add to that faster and slower delay times (reverberations) ..and it becomes a virtual wall of dischord.  Ever hear how a lot of people in a cafeteria sound? You cant hear what they’re saying , but you can hear the loud dischord of murmur and virtual wall of sound. If those people were a choir singing in notes and keys of varying chord structure, then it wouldve sounded clear. Imagine sound as if its a little rubber superball and every time it hits a surface (wall, floor, ceiling) it clones into two superballs ..until the room is filled with all the billions of them. The speeds and directions they’re moving becomes the dischord sound when they’re all bouncing around like crazy and in all the different directions.  You can try to cancel all sound out with absorbing materials like the rugs and couches and curtains that Scott mentioned. Or you can try to direct the sound in focused directions. (think ampitheater)
By controlling sound to all move in the somewhat same direction, it will amplify itself from those reverberations, yet, wont go off in a billion tangents. So instead of making a completely sound proof room, you might also just need to direct the sound better, and then you will hear it better.

Frank

Hi,

Yesterday I was watching HGTV and caugt their show on the International Builders Show 2008. There was a demonstration for a company called Quietrock who claim to be able to have sound proof drywall which means no loss of useable square footage or complex construction.