No, not really. Soundproofing means preventing sound from entering or exiting a volume. Because of the way sound works, a quite small leak will result in quite a lot of sound entering or exiting a volume.
20 dB is a ~4x increase in perceived sound volume, but a 10x increase in the actual pressure of the sound wave. So, oversimplifying, if you block off 90% of the sound waves entering a volume, the remaining pressure spreads out to 10x weaker waves... which are still 25% as loud. Keep in mind that this is covering 90% of the floor, walls, ceiling, doors and windows in perfectly sound-blocking material, which does not exist.
To reduce volume levels by 90%, you need to perfectly isolate 97% of the sound leaking in. You literally need to build a new room inside the old one. That's before you even account for the fact that your ears will adjust and sounds need to be much quieter to keep from picking up on them.
Preventing sound from exiting a volume is even worse. Sound has quite low absorption coefficients even in things like open cell foam; anechoic chambers rely heavily on shapes that trap sound and cause it to echo through foam dozens of times so that it's sufficiently attenuated before it bounces back out. Most reasonably airtight rooms are painfully loud because sounds you normally consider quiet (eg footsteps) are not attenuated as normal.
Keep in mind that even if you think a room is reasonably airtight -eg when you have an open window, your door closes far more easily than when the window is closed- it's really not at all. You've probably got vents etc that allow lots of air to move in and out of the room.
In a well-sealed room, sound will echo ~100 times (a second or two) before attenuation makes it much quieter. That pressure is just bottled up and it will escape through even tiny cracks, and if you were to listen at one of those cracks you'd hear much more clearly than if the room wasn't soundproofed at all. In that case, the soundproofing is just acting like a funnel or a crack in a pressure vessel. Unless you've got comprehensive soundproofing and a way to increase attenuation, all you're doing is causing the sound to escape from smaller spots.
When you see people recording and they have just a few acoustic panels up, the point is not to make the room any quieter. In fact they usually want the opposite- you want sound to exit the room as easily as possible, to prevent echoes. If you hang up too many panels, you prevent that from happening and you don't really decrease the volume of sound from the outside.
Acoustic panels are best used sparingly to dissipate or break up echoes from a very specific place, like directly in front of the recording, or behind electronics/noise sources.
that was a very good explanation. I'm awaiting for my remodeling to be done so I can see if I spent all that money for nothing. Got a new wooden door and new windows. If everything works, I'll share my project here on HN.
