Soundproofing is the process of trying to control the amount of sound that escapes from a room or the amount of sound that leaks into a room. There are only three ways to stop noise. First, you need to create space between the source of the sound and the listener. Next, mass is needed to help absorb the noise. Lastly, you need to dampen the noise by using the correct materials that will absorb noise. The do-it-yourself handyman can soundproof a room if he knows what materials to use and the correct applications.
Build the walls thicker than the standard 2-by-4 wall construction. This will allow you to use all three techniques to help control the noise for your application. A 2-by-4 wall is 4 and 9/16th of an inch thick compared to a 2-by-12 wall that is 12 and 9/16th of an inch thick. This technique provides more air space and room to add noise-absorbing materials
Apply products to the walls that are specially designed for helping to control sound. This can be accomplished by using speciality drywall material, carpets, and ceiling and wall tile materials. These will help to dampen the sound.
Install a second layer of plasterboard to all of the walls and ceiling in the room. This will provide more mass and help to dampen the sound as it tries to pass through the wall. Applying silicone between the layers of plasterboard will add air space and will isolate noise from passing easily between the two sheets of drywall. Place quarter-size dabs of silicon every 16 inches on one sheet of drywall. Let this dry before screwing the plasterboard together. A stud finder and a screw gun will make this task easier.
Repeat the last step for the opposite side of every wall, ceiling and floor of the adjacent rooms. This will double the mass and absorption of the wall system.
Install a high quality thick carpet pad and a quality carpet to the rooms floor. The carpet will help dampen the sound. In new construction, have the general contractor add insulation in the floor cavity to add mass. The same principle is used for the ceiling. On older homes you can blow in insulation into the air space between each stud to add mass and dampen sound from passing between the rooms.
Lower the ceiling by installing acoustical ceiling tiles. This will add space between the plasterboard and the ceiling tiles. The tiles will help dampen the sound in the room.
Apply weather stripping to all of the doors of the room you are working on. Add a threshold that will seal the bottom of the door for interior doors. Replace hollow core doors with solid core doors to add mass and reduce sound.
Build a window plug for all the windows. Measure the height and width inside the window jamb. Cut a piece of MDF (medium density fiberboard) to fit inside the jamb. Apply plasterboard as in Step 3 to both sides of the MDF. Screw on a set of handles to one side so you can easily install and remove the window plugs as needed.
Wear safety glasses when using power tools.