Sound proofing our ceilings is probably the most difficult part of our room to deal with, simply because we have to support any material type we decide to use with our existing ceiling or by building a new structure. If we are dealing with a lot of noise from adjacent rooms, we will need to measure how large of a noise problem we actually have, so we can figure out exactly how much material we need to use. We definitely don’t want to use any more material than the noise issue demands since we have to support any material we will use with the existing structure or build a new one.
Measure The Problem
Our first task is to measure how much noise we have to deal with. If our noise is coming from our own room and we need to seal that noise from drifting into other rooms, we need to measure the noise from within our room and start with that issue first. If the noise is external to our room, we need to measure it and find how much of a noise issue we have to deal with. Remember from past discussions, that both noise sources whether external or internal require different forms of acoustic treatment. Barrier technology is used to keep noise from entering our room from external sources and also keeping our own noise levels generated in the room from “bleeding” into existing structures. If we need to control room boundary reflections and general small noise levels within our rooms, we can use absorption technology.
If our noise levels are determined to generate from external causes we will need to use barrier technologies to place a barrier between us and the noise. Once we have determined how much noise we have to isolate ourselves from and at what levels we are dealing with, we can choose the appropriate barrier materials and technology we need. All barrier materials have mass and weight associated with them. Barrier technology is all about controlling vibrations from sound pressure waves that are produced by our noise source. Mass and high density materials have to be arranged in a certain vibrational controlling method termed constrained layer mass damping. Multiple layers of materials with different densities are arranged in a manner that produces the least vibrational transfer of energy.
Build a Noise Barrier
To build a barrier for our ceiling, we will start with two commonly found construction materials. We can use plywood and drywall or gypsum board. We can start by taking our plywood piece with a 1/2″ thickness and then placing an “acoustical glue” between the plywood and the 3/8″ layer of drywall. Acoustic glue never hardens completely and the two materials that it is bonding with “float” against each other. This layering of materials technique is termed constrained layer mass damping.
In a constrained layer, mass damping configuration, all layers of high density materials must be separated or mechanically decoupled from each other to minimize vibrations from transferring from one piece of material to another. By isolating each higher density piece of material with a lower density or viseoelastic damping compound, the vibration must travel through all of these materials and as it does it losses energy and this is our goal. If we can reduce the vibrations strength, then we can minimize the sound or noise energy that vibrations can produce.
To further increase our barrier’s strength against vibrations, we can physically arrange the materials in ways that will reduce vibrations. If we are using multiple layers of plywood, we can arrange one piece of plywood one grain direction and position the other in a cross grain direction from our original piece. This running of the grains in different directions can go a long way to assist us in reducing our vibrational levels.
Installation Is Critical
Installing our new barrier technology requires care and careful consideration. We must install our new ceiling in a manner that continues our vibrational isolation theme. We must separate the new ceiling from the old or existing one using vibration isolation techniques. We first install a series of isolation tracks that our new ceiling will attach to. These tracks will physically decouple our new ceiling from the existing one and create an air space between the old and new ceiling. Air is also a vibration reducing material and can be effective as another layer for vibrations to have to work themselves through.
Watch Those Edges
We must pay particular attention to the edges of our new ceiling. In most ceilings, the ceiling edge surfaces touch the existing walls. There is no gap or space between the edge of the ceiling and the wall surfaces. While this looks nice in normal environments, it can be detrimental when dealing with vibrations that contribute to noise. Our new ceiling or barrier must have itself physically isolated from our existing room structure by leaving a gap between our new ceiling and existing wall structure. This physical gap serves two purposes. First, it isolates our new ceiling from the walls which will prevent the vibrations from our walls from entering our new ceiling barrier. Secondly, the small gap will prevent vibrations from our ceiling from entering into the walls and causing more issues. This small gap will be filled in with an acoustical sealant.
Absorption Inside Our Rooms
Noise levels in our room can be controlled through the use of absorption. We can absorb excess low, middle, and high frequency energy inside our rooms using many different types and forms of absorption technology. If we have noisy office equipment, we can place these units in sound isolating cabinets. HVAC noise can be controlled by lining our duct work with special foam technology that can reduce the air flow in the duct work itself. We can also reduce the fan noise by lowering the fan speed to reduce air flow. We need to lower the air flow down below 340 feet per minute.
Sound proofing your ceiling is not an easy task. If we have to build a barrier between our existing ceiling surfaces and outside noise levels, we really need a professional to design and install it. One can spend more money and energy making mistakes by guessing how much material to use and building and installing it incorrectly, than it would take to actually have a professional do it. Controlling noise levels within our room using absorption technologies can be a do it yourself project with adequate research done ahead of material selection and installation. `