Soundproofing materials use and proper selection are determined by how much noise level we are dealing with and where that noise level originates from. If the unwanted noise is originating from the outside of the room or structure we seek to soundproof, we need to use barrier soundproofing technology. We need to place a barrier between us and the noise we are trying to get away from. If our noise levels originate from within our room we are trying to soundproof, we will have to use absorption technology. On some occasions, we may have to use both barrier and sound absorption technology together to absorb excess energy within our room and to keep that energy from leaking into adjacent structures.
Building a Barrier
Barrier technology is just what the name implies. We construct a barrier between our room and the noise source. If we live on a busy street and the traffic interferes with our recording studio, we need to build a barrier between us and the car traffic. If we live in an apartment and we have a noisy neighbor, we need to build a barrier between our neighbor and our apartment. Barrier technology is not cheap to do and requires special construction techniques. One must choose what materials to use and how many. One must also decide what construction method we will use in assembling our barrier. Once we build our barrier, we then must install it within an existing structure. Care must be taken to mechanically decouple our new barrier wall or structure from the existing room. We must use vibrational control assembly and installation techniques.
Absorption technology is a different animal. Absorption technology really has nothing to do with mass except at low frequency absorption issues. Absorption technologies are usually light weight and easily positioned. The process of absorption is a physical one where sound energy is converted to heat. Once this conversion process has taken place, the sound energy is lost forever. It can not be changed back to sound once it has been changed to heat. There are numerous sound absorbing technologies available in the marketplace.
Barrier technologies are built with standard construction materials. Some materials used in barrier technologies include plywood, multiple density fiberboard, drywall, and even concrete and lead. Barrier technology materials are heavy and have high densities to minimize vibration. Vibration control becomes the design goal of a barrier. Air born sound energy strikes the barrier and is then converted to mechanical energy. This mechanical energy travels through the barrier we just constructed and these vibrations must be reduced in a systematic way to insure that they are reduced when they enter our room. It is difficult and very expensive to stop all noise issues. The best we can try and achieve is to lower the outside generated noise levels below a minimum acceptable level.
Must Reduce Vibrations
To minimize vibrational levels, we must construct our barrier in a vibrational reducing manner. The correct term for this construction methodology is termed constrained layer mass damping. We use different layers of materials that are constrained or combined together to achieve a mass that then serves as a vibrational damping unit. Each layer of our several material barrier must be assembled in a way that reduces vibrations. For example, if we are using plywood and drywall as two of our barrier materials, we must join these two materials together with another layer of material. In barrier technology creation the more materials used usually is for the better. We can join our plywood and drywall together using an acoustic glue that will provide the necessary adhesion benefits to keep the two materials together but not so together that the assembled unit acts as a single piece of material. Remember, our goal is to reduce vibrations by forcing them to go through different materials all with different densities. This process correctly done, can significantly reduce vibrations.
Absorption technologies can be common acoustical foams, draperies, numerous fabrics, and even furniture. Our acoustical goal with absorption technology is to provide enough of the chosen material, so that we can cover all the necessary surfaces of our room we wish to soundproof. A combination of sound absorbing materials usually works best. In most rooms where soundproofing within our room is the goal, we must cover all wall surfaces with sound absorption technologies and even add additional materials throughout the room to absorb lower frequencies than standard acoustic wall treatments can handle. A large stuffed chair can be used to absorb lower frequencies that our acoustical foam panels can not. If we want to scientifically attack our absorption issues and deal with them scientifically, we can use low frequency absorbers that are specifically designed to handle the low frequency energy issues specific to our individual room.
Sound proofing materials are problem specific. If we need to stop unwanted noise from outside our rooms, we need to build a barrier between ourselves and the noise source. We need to use materials that have high mass and densities. Barrier materials include plywood, drywall, concrete and even lead. Barrier materials have mass and density. If we need to absorb unwanted energy from within our room, we use absorption technologies. Absorption technologies include acoustical foams, draperies, and even a large chair.