First, seal both sides of gypsum board with light steel keel, and put sound insulation cotton inside. This wall should have at least two or three floors, and the outside should be painted. To make a soft bag inside is to make a lot of small frames, which are covered with sponge and covered with bread cloth, and then nailed to the wall, which is both beautiful and sound-proof! When you're done, there's no signal on your mobile phone! However, workmanship and materials are very particular. For example, gypsum board should be at least 12mm thick, which is absolutely good. This is the job of the radio studio. If you want to save money, make one or two fewer walls. I suggest not saving the last program! Because sponges absorb sound! Can say so much! Decide for yourself!