Soundproofing better a stud wall.

You are likely to get a industrial look in the room useing the bords or mute clips but you can also use soft thick materials that is big enough to cover the walls this will work also.

Apply soundproof insulation

Soundproof boards are there for a reason, as long as they are applied correctly. Either build a separate stud frame (not touching the wall you are trying to sound proof) and insulate or, use resilient bars or furred channels with the clips give better performance (onto the wall).. Either way, two layers of soundproof boards should be put up with the second layer covering the joints of the first one. Leave a 3mm gap around the perimeter and fill with soundproof filler. Then skim or joint fill..

Thats right they are blue in colour and used just like normal plaster boards they can also be skimed the same way for the same plaster finish