Room Acoustics

Definitely, acoustic panels improve the things very much. And you can have them very cheaply. Now-a-days different types of very effective but cheap panels are available in the market. They are attractive also. Please visit www.acousticmanufacturer.com/Noise-Barrier-on-Temporary-Fence-for-Construction-Site.html to know the details.

Among the least expensive options is acoustic foam.

http://www.thefoamfactory.com/acousticfoam/acousticfoam.html

I'm told it's not as good as fiberglass and wool, but at a fraction of the cost it can be "good enough".

Those "foams" are a bit too soft for doing much absorption or refraction. They do help a little bit with bass trapping if the speakers are very close to side and/or back walls. I'm using their 2" wedge foams in my study where I'm forced to keep my monitors in room corners.

@kalali 

I agree with you. Note, however, the foam factory publishes a fair amount of specifications regarding their foams NRC absorption ratings. In fact they provide independent third party lab results too. So while what you are saying is true that they don't do much, they do *something* in the way of absorption. In my case I wasn't looking for much absorption, just something to take the "edge off" sound directly hitting dry wall.  http://halr.x10.mx/AV.jpg 

Also, according to what I was told by a GIK Acoustics rep, one needs 2.5 inches of foam for every 1 inch of their fiberboard. I went with 2 inches foam.