In Part I and II of How to Sound Proof Your Office, we discussed how first and foremost, we must quantify what our actual noise issues are. We must put a number to the noise. Next, we need to find out if the noise is being generated from outside the office or from inside the office. Depending on the noise source and position, we will use different technologies to minimize the noise issues. We minimize so noise levels do not rise above acceptable levels within an office environment. In most situations reducing pressure levels that allow for normal speech and work related endeavors to move along uninhibited is the acoustic goal. Eliminating noise completely is usually not an option. If our noise is generated from outside our office room, we discussed barrier technologies and their application. If the unwanted noise is coming from within our office room, we must use absorption technology.
Reflections from our office wall surfaces confuse our brain’s ability to localize sound sources. Reflections also mix and blend with the vocals blurring and smearing our voices inside our office room. Their is a term for this phenomenon. It is called speech intelligibility. We must have reflections in our office minimized and our reverberation times in the office room below certain levels in order to hear speech clearly and “intelligibility”. There are a series of numbers that one needs to look at, but a discussion of them is not necessary. These numbers are easily achieved using absorption technologies.
How Much Noise?
The most important thing we need to consider is how much energy will be generated from within the room. Once we know that, we can definitely choose the correct rate and level of absorption we need to use. Normal office pressure levels from 65 dB to 70 dB can be maintained with using numerous commercially available and affordable products. If you have a dropped ceiling, you can use acoustic ceiling tile that is made to fit in those ceiling types. One can also add absorbing material to the backside of the ceiling tile, for added absorption values. There are numerous wall treatment options for controlling wall surface reflections. Most are some type of fiberboard filled or unfilled with a fabric covering stretched over the face.
Door Must Be Sealed
The door in our office must be sealed, so that when it closes, there is no air leak between all the door surfaces and the door. Even a small opening can allow a large amount of unwanted sound energy to “bleed” into the office. Think about it as a hole in a dam. All the water pressure built up on the other side of the dam or door is forced into that small opening and then into the office room itself. A strong commercial grade weather striping can be an affective seal. Brush type strips are also used that have a series of bristles on them, so that the door pushes them in one direction which adds a sealing action to the joint or opening.
Windows in our office are the weakest link in the acoustical chain. Windows create harsh surface reflections and allow for sound energy from the outside to come in. Double pane windows with a vacuum seal between each pane is a good start. Triple pane windows are better. This is no place to try and save money on. Windows are expensive and are very important. Make sure your budget allows for some type of window covering, so that one can cover the glass to reduce sunlight and stop unwanted window reflections from entering our office environment.
Office equipment noise is another issue. One piece of electronic equipment in our office does not generate or add much background noise to the total amount in the room. However, once we have 6 or 7 pieces of equipment in the room, both noise and heat levels can rise. Separating the equipment from each other and moving the equipment to different parts of the room is an option. However, in most office scenarios, this is not possible. Keeping the equipment all together facilitates use and ease of operation. Placing the equipment in sound isolating cabinets is a good option. The professional recording market will have these types of cabinets, since they deal with equipment noise on a regular basis. These cabinets will also have venting for heat and air movement.
If the excess sound energy is coming from inside our office rooms, we must use absorption technologies to reduce the noise levels, so that the work environment is quiet enough for all parties concerned. We can use acoustic tiles for our ceiling and even improve upon their performance by adding absorbing foam to their backside. We can use fabric covered panels for the wall surfaces. We just need to make sure that they are absorbing at the proper rates and levels for speech intelligibility. Windows are our weakest acoustical link and must be treated so. Office equipment noise can be reduced through the use of sound isolation cabinets.