More BS* + Beer
In this episode of the BS* + Beer Show, we host Bennett Brooks and Michael Crane talking about sound control in our homes. Topics covered include those Bennett addresses as an acoustical consultant: sound isolation between living spaces, HVAC mechanical system noise solutions, and exterior noise management. We learn about sources of noise (including ductwork; faster air is louder air), two types of sound isolation, what the IRC says, acoustics design criteria (ANSIS12.2 rating), mineral wool insulation and double-stud walls for sound absorption, how to “get some weight behind your construction,” and sound decoupling. Bennett shares a few case studies that identify potential noise issues and demonstrate how best to manage construction noise. Plus, the live-audience questions in the comments section below are up for further conversation. They didn’t make it into the show because of time limitations.
Enjoy!
Bios
Bennett Brooks is president of Brooks Acoustics Corporation (BAC) an acoustical consulting firm comprising engineers and designers who specialize in sound for the built environment. Bennett is a graduate of the Massachusetts Institute of Technology (BSME), and the George Washington University (MS-Acoustics). He is a licensed professional engineer, fellow of the Acoustical Society of America, member of the Institute of Noise Control Engineering, member of the Audio Engineering Society, and past president of the National Council of Acoustical Consultants.
Michael Crane is a business development manager for MP Global Products, specializing in the construction and building materials industry, with a focus on wall assembly applications. Michael leads the Building Materials and Acoustics division, spearheading the launch of practical acoustic solutions. He holds a Bachelor of Science in Business Administration from Mississippi College and has held key roles at Service Partners, Installed Building Products, Insulation Distributors Inc., and ROCKWOOL Inc. He is also the organizer of BS* + Beer in Austin, TX.
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The next show is on October 3 from 6-7 p.m. ET.
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Kiley Jacques is senior editor at Green Building Advisor.
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7 Comments
Mike asks: How to deal with internal sounds/echos with high-performance homes–typically well air-sealed and well-insulated, with triple-glazed windows and lots of hard surfaces, and all-electric appliances and equipment that make a variety of hums, vibrations, whooshes, beeps etc.?
Mike asks: Bennett mentioned that you can quantify occupant comfort–how?
Comment from kurt: SOUNDPROOFING=keeping sound in or out vs. ACOUSTICS=how the room sounds when you are listing to TV/Music while in it.
Kurt also says: Soundproofing method is based on the frequency bands of the sound to be restricted (low, mid, highs). Highs easiest to solve using carpet, foam, etc.. Lows are the hardest to control and require walls/doors/windows/floor/ceilings/ducts that all equally have high weight, rigidity, isolation, and air tightness.
Jeff asks: what's the reco'd practice for sound insulation/dampening for high-end media rooms? two layers of gypsum with damper matting sandwiched between them, finish off with acoustical paneling on the finish/outer layer?
Ian asks: All else being equal in a single family wood frame home, how much sound attenuation would you get from 5/8” drywall vs 1/2?
Hap asks: What were the acoustical interventions on the wavy island house?
Allison asks: Why do so many restaurants fail to implement what’s known about acoustics and noise reduction?
Unknown authors:
Might some caulks not tested for acoustics be just as good because they don’t dry out and harden? And which ones are they?
What recommendations would you have for working with an existing home/space? Would you lean towards adding materials or changing materials out like wall panels, insulation, etc?
Which is better: Green Glue or mass-loaded vinyl?
What is Quiet Rock?
Do gaskets do anything or once you compress them are they useless?
Does quiet rock screw up cell signal?
A rather important message: Airtight is quiet.. air leaks = sound leaks.
Re. restaurants - I had a friend (now passed away) who owned a very successful small restaurant chain. He told me that they purposely used uncomfortable chairs and kept the noise levels up so that diners would leave promptly after finishing their meals.
I guess you could say they were designing the sonic environment, but for a different set of criteria.
I completely agree!! As someone who visits many different restaurants when traveling, I cannot help but look around and think to myself...... Why??? I have seen some restaurants and breweries that knock this out of the park and many that you cannot even have a conversation.
Alright guys let's try to get some of these questions knocked out. I apologize for the delay. I am going to reply with my best response for each one that I can separately so we can dive in deeper if needed. Starting with the first about internal noises in high performance homes:
When it comes to beeps, hums, whooshes, etc... I think we can all agree that it can be a nuisance and really dig into the comfort of living in that space. From my building materials background let's start by discussing what we can control in the build process for these homes. There are really two main ways to manage reverberations within a room and that is with absorption and diffusion. There are of course other ways to manage the noise through dilution with music, white noise, etc..
I am a huge fan of diffusion. Which helps eliminates echos by scattering the noise. It is also aesthetically pleasing and adds contrast to those hard surfaces. Absorption is also the other method where we are adding soft surfaces to the room to absorb those sounds and eliminate echos. By incorporating these two strategies in at the design phase would be ideal but both of these strategies can be added later on as well.
Will these two strategies knock out the noises that are in question? To be honest, I don't know and just like our building science talks... It depends. If we are talking about noises that are tunneling through a house then yes, but if we are talking noises that are originating in the same room as the occupants then I think it is going to take more methods to help drown the noises down where they are not so noticeable.
This is going to be in response to Jeff's question regarding the recommended practice to sound insulating/dampening for high-end media rooms:
Unfortunately, there is not a one stop fix all solution to sound control. The principles remain the same in which we formulate a strategy, but every project has different noises, frequencies and other variables that we have to account for. As Kurt mentioned above, we want to address lows, mids and highs.
One of the main variables is the location of the media room. Is it next to a bedroom or is it located on the second floor with a subwoofer that rattles the entire mid-floor assembly. A good soundproofing plan begins with knowing all the variables and the limits of the strategies that are employed.
The example that Jeff provides a good start with the strategy of two layers of drywall which act as a barrier and a dampener which can be an acoustic fiberboard product, a viscoelastic compound or as Mr. Brooks mentioned even an acoustic sealant. The absorption method employed is a management strategy and will affect the acoustics in the room but not in the wall assembly to minimize vibrational energy through the wall. There is also no decoupling method employed with this assembly which could be a big mistake for the success of the media room not disturbing others.
These are just the thoughts that came to mind when reading over this question.
Next up is Ian's question regarding the performance of 1/2" drywall versus 5/8" drywall.
This of course depends on the wall assembly design but even then, there is very little noticeable difference between the two thicknesses on paper. If you take a look at a sound chart between the two, you can see the difference. I know that Mr. Brooks can speak to this question more in detail. For me personally, I would opt for the 5/8" drywall.
Very helpful responses, thanks Michael!
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