Absorption coefficient of a material determines how much sound is absorbed by the material.
To build a soundproof room, Heavy curtains and carpet can be used. They reduce reverberation.
Reverberation means an echoing sound which persists for some time. For example, when we bang on a huge piece of metal, we hear the reverberation even after we stop banging.
Carpet and heavy curtains, and wood. concrete is more liable to echo. with the heavy carpet, its thick enough to weaken the sounds, as well as carpet. wood is thick and big enough to do the same aswell. hope this helps.
