Low end rumble

[ddymann]

I am finishing a new studio in my garage. it is basically a room inside the garage that is not touching any of the outside walls or the ceiling. the outside of the walls are made out of drywall + mass loaded vinyl the inside is 3 1/2 inches of fiberglass cover with a cloth frames.

The room sounds very nice but I do have a problem with 50 hz low rumble bleeding from the outside
it's very low and you can mainly hear it in the corners at rush hour ( I live about a mile away from the highway and 4 - 5 miles from an airport.


any ideas how I can try to lower this rumble ? if I can get it to be 6 db- 10db lower I will probably be okay. I can probably double
the mass loaded vinyl on the walls facing the outside walls or add quiet rock on the drywall facing the inside of the garage. just not sure what might be the best way to go. bass traps maybe ? . the peek of the rumble is at 50 Hz.

[SAC]

You are describing a problem with sound transmission through boundaries - isolation.

No amount of internal treatment intended to control reflective issues is going to address isolation issues.

The forum is full of threads addressing "sound isolation" and sound transmission". I suggest you do a search and peruse them.

But I will warn you up front, you are not going to like what you read. The solution is neither simple nor inexpensive - and all involve significant structural modification.

[jhbrandt]

Originally Posted by SAC

But I will warn you up front, you are not going to like what you read. The solution is neither simple nor inexpensive - and all involve significant structural modification.

+1 and

Cheers,
John

[ddymann]

I red allot about sound isolation before posting this the reason I was posting is that it is mainly a problem in one corner and I still have allot of option
just not sure which one will most likely to work. an as I mention I will be happy if I can get couple of dB improvement ( 6 will probably do it 10 will be fantastic ). what will be the best material to use to reduce 50hz ?
mass loaded vinyl quite rock ? any idea ? I think my structure if right only not
robust enough.

[latestflavor]

well, there's always the approach of slapping up more drywall + greenglue until you're satisfied...... but beyond that, isolation is much more tricky from a layman's perspective

i guess you have a choice to start slapping up mass or starting over with the proven, detailed and effective techniques.

[SAC]

If you have read anything about sound isolation you should know that the envelope is a site wide issue, and is not limited to one corner nor to simply one material!

And you either block the energy to particular level, or you do not.

I might suggest examining the NRC documents linked in a number of threads discussing various tested structural systems providing various degrees of quantified isolation and also analyzing flanking paths.

And in the meantime, stop looking for some 'magic material that you mistakenly think will solve the problem - it won't, but you will discover lots of expensive products making lots of claims that may add slightly more mass than regular drywall for exorbitant amounts of additional cost.

In other words, stop reading product brochures claiming to describe remedies for sound isolation and start reading structural engineering reports describing the systems that can be constructed with normal commodity materials following proven construction methods.

Why do I have that sinking felling that the next idea will be regarding green Glue???

Edit: oh geesh! Am I psychic or what?

Here:
Start with some of these downloadable docs:


Here is a generic listing of downloadable documents available from the NRC on Isolation methods. The NRC is an excellent source of tested construction methods. Pay particular attention to the doc regarding flanking paths.

You first need to determine exactly how much isolation you require: (max internal level in db SPL - maximum external level in dB SPL) = minimum amount of isolation required.

Owens Cornng Design Guide
(http://www.gearslutz.com/board/studi..../30011340.pdf )

NRC (National Research Council) docs (Choose the docs that are appropriate to the construction type):
Sound Transmission Loss Through Concrete and Concrete Masonry Walls
by Albert Litvin and Harold W. Belliston
www.cement.org/bookstore/profile.asp?itemid=RD066

Sound Transmission Loss of Masonry Walls
by Warnock and Monk
www.nrc-cnrc.gc.ca/obj/irc/doc/pubs/brn/brn217/brn217.pdf

Sound Transmission Loss Through Drywall and Block Walls
by Warnock
www.nrc-cnrc.gc.ca/obj/irc/doc/pubs/ir/ir586/ir586.pdf

Gypsum Board Walls: Transmission Loss Data
By Halliwell, R.E.; Nightingale, T.R.T.; Warnock, A.C.C.; Birta, J.A.
www.nrc-cnrc.gc.ca/obj/irc/doc/pubs/ir/ir761/ir761.pdf

Controlling Interoffice Sound Transmission Through a Suspended Ceiling
by R.E. Halliwell and J.D. Quirt
www.nrc-cnrc.gc.ca/obj/irc/doc/pubs/nrcc33097/nrcc33097.pdf

Flanking information:

System Details That Work (Leaks and Flanking)
by David Quirt
www.nrc-cnrc.gc.ca/obj/irc/doc/leaks-flanking.pdf

Guide for flanking sound transmission in wood framed construction - airborne sources
by Nightingale, T.; Quirt, J. D.; King, F.
http://www.nrc-cnrc.gc.ca/obj/irc/do.../nrcc49468.pdf

Controlling Interoffice Sound Transmission Through a Suspended Ceiling
by R.E. Halliwell and J.D. Quirt
www.nrc-cnrc.gc.ca/obj/irc/doc/pubs/nrcc33097/nrcc33097.pdf

Airborne Sound Insulation in Multi-Family Buildings
by J.D. Quirt and T.R.T. Nightingale
http://www.nrc-cnrc.gc.ca/obj/irc/doc/ctu-n66_eng.pdf


Also, you may want to obtain copies of both Rod Gervais' Home Recording Studio Build it Like the Pros and John Brandt's Build Your Own Home Studio books regarding the construction of home studios. If you are going seeking help and are asking questions, you might show them the respect of first reading their material, and then asking for clarification as necessary and not simply expecting them to repeat and explain the concepts if you are not first willing to read what they have already extensively written on the subject.

[TPBaker]

What is the construction of your ceiling?

[ddymann]

Thanks for all the information SAC, I will start reading tonight.

[ddymann]

there are 2 by4 that are going from one side to the other. over them I laid quarter inch plywood and I glued 1/4 mass loaded vinyl above the plywood. under the plywood I hang R19 Fiberglas and I close it with cloth. above all that is the garage celling. basically asphalt shingles on top of plywood and cover with fiberglass at the bottom which I know is not a lot and wondering if that is the problem and what can be done. Thanks .. David

[latestflavor]

its probably a combination of flanking and lack of mass. i wasn't quite following which side the plywood and fiberglass were on, but at the very least you should be using isolation clips and several layers of drywall if possible.

there's obviously so much that can go wrong, why don't you read rod G's book. the devil is in the details when it comes to construction techniques with isolating sound. that book in particular is made for the "dangerous" DIY'er in mind.

[ddymann]

Thanks latestflavor. There is sure not allot of mass in the ceiling .unfortunately
adding any dry wall will not be physically possible at this point ( access is very limited ) .what I can do is to lay drywall on the
celling with out making it one surface ( there will be gaps in couple of places where the Garage beams are now.
Do you think that will help ? ( it will make the celling heavier ) will it make sense to put fiberglass first then the drywall plates ?
that will make some form of cavity in between the existing celling and the extra weight. maybe I can add spacers so the weight
will not squeeze the fiberglass to practically nothing.

David http://www.freshcutsoundeffects.com