Have you ever walked into a room with excessive noise? Where the echo and reverberation produced such a "roar" that your own thoughts could hardly be tracked? In this situation, the first thing that needs to be done is to consider whether to prevent the noise from entering your space.
The purpose of soundproofing is to keep sound from escaping from your room. You can remember how the noise will complain to all the neighbors. Someone likely added some kind of material to the walls in an effort to block the sound. This is a good example of a sound-proof attempt. If you want to make your office soundproof, then you can visit http://www.yourspace.tech/.
Sound absorption is the mechanism where excessive sound frequencies at high, medium and low rates are absorbed to remove unnecessary "ringing" and reverberation such as slap or flutter echo.
Have you found that after you moved to your new home, the echo was greatly reduced or even eliminated? The explanation is that there is little, if anything, to absorb sound frequencies when a room is empty. But when hanging your clothes or bringing in your furniture and other objects, they help absorb the sound.
Often the excessive noise is still an issue. At this point, sound absorption is most likely desired. This can be achieved in a variety of ways. There is a variety of materials that are used to absorb sounds such as fiberglass insulation, rock wool, a huge variety of various foam and various cotton fiber blends.