Whats an easy way to sound-proof a room?
I assume this is for recording purposes? If so, what instruments do you plan on recording?
Right off the bat, I can tell you that it may be more economically feasible to use a medium to large walk in closet (If you don't plan on recording drums, and you have one, that is). As long as there is minimal outside noise to begin with. Farthest away from roads, loud children etc etc.
Next you should consider what type of material to use in lining the room. A thick, soft lining will minimize reverberation. Thin, a little less. If you look around on the website I linked to, it should all be pretty self explanatory.
I'm not really a huge expert on the subject because I use an audio interface to record guitar and keyboard parts, but if you plan on recording acoustic instruments there are a bunch of DIY links that go into greater detail - depending on what exactly you had in mind.
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