ACOUSTICS at Large
Questions About Acoustics? Here Is Your Forum: by Keith Peterson
hroughout my carrier I have had the pleasure of working on projects with many great architects, engineers, contractors, and manufacturers. In recent years awareness about the importance of acoustics in architecture has increased. Acoustics is an important topic that comes up on just about every project. The purpose of this forum is to create an open dialog on the topic of acoustics as it pertains to the built environment. CISCA members can use this as an information resource. I am going to use technical terms, but we are going to make this very real world and take some of the mystery out of this topic. There is something intimidating about acoustics, because we can’t see sound. So how do we control what we can’t see? We have to learn what to look for and how to qualify architecture in an acoustical manner. Once we learn how to do this it becomes much more manageable and a lot less intimidating. Defining the terms Basic architectural acoustics can be broken out into two topics. There is more to it than this, but it is a good starting point: • Interior Room Acoustics: How sound behaves within in a space. (The room is reverberant, echoy, dead… I can’t understand what is being said… This orchestra sounds incredible in this space… etc.) • Sound Isolation: How well boundaries of a space stop sound from going out or coming in. (We can hear the street noise…We can hear the neighbors dog running around upstairs... I can’t believe how quiet this space is for being in the middle of the city…etc.) Between these two topics I am sure that one of you has a real world question to ask. Here is a sample question to get things moving; this was a problem that I had to address last month: Q: “ I have a problem with the tenants in my building. One of the tenants is a DJ and the other one is a Law Office. You can see where I am going with this; can I put 52
Summer 2014 | Acoustical INTERIOR CONSTRUCTION
some acoustical panels up in the law office to stop the sound?” A: No. Acoustical panels are interior room treatments associated with an NRC value. They are meant to control reverberation within a space, and they have very little effect on transmission loss. A solution to this problem would be to increase the STC rating of the wall assembly and any other potential sound paths. This could be as simple as adding a layer of dampening drywall, or as complicated as building a decoupled assembly using isolation clips and additional framing and drywall. It all depends on how many decibels we need to reduce the noise to please the Law Office. Feel free to ask for more details on my answer or come up with entirely new questions. Every issue will have two new topics to learn about and ask questions on. From time to time I may also get on the soapbox to offer a particular view on some industry related issues. This will not be meant to attract converts, but simply to expand the discussion and create understanding. Definitions: The good people at Owens Corning have put together a nice list of acoustics terms and definitions. If I use a term that is unfamiliar to you, use this as a quick reference. We can also explore any of these definitions in more depth in our Q and A. http://www2. owenscorning.com/around/sound/glossary.asp Contact Keith Peterson with questions or comments at: Keith@kpetersonassociates.com Keith Peterson is currently the President and CoFounder of New England based K. Peterson Associates Inc, an independent manufacturers’ representative firm specializing in high quality architectural products. Keith Peterson holds a Bachelors Degree in Acoustics from Columbia College Chicago and has a working relationship with many of the contemporary experts, on the topic of Architectural Acoustics.