flanking

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zorf

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been searching but i'm unclear on this soundproofing concept:

for the walls in my teeny one room "studio" :
I used acoustic caulk in the inside of my stud bays, stuffed insulation in
there, installed quietrock, used acoustic caulk, taped the seems, etc.

For the cieling i wanted to make it one dead cloud, so i caulked the seams
as above and stuffed insulation (ultratouch) and left it open.
Is all the work i did to the walls useless unless i sheetrock the cieling too?

I don't have a lot of cieling height to spare (7 feet exactly) so i don't have
the option of suspending a cloud.

this is to keep sound from leaking outside (neighbors) and to a lesser
extent, upstairs.

thanks as always for all the helpful folks here.
 
Zorf,

you're picturing it wrong to begin with...........

a ceiling cloud is good for room ambiance - and no good for isolation -

for isolation you need a MAM system (Mass Air Mass) - to avoid flanking problems it HAS TO BE a decoupled system.

In other words - you have to take the existing struture out of the picture...........

then you have to add mass (insulation alone won't do anything to help you)

So - for your walls - the best thing you could have done would have been to use RSIC ith hat channel (decouple from existing structure - then 2 or 3 layers of 5/8" drywall (quiet rock is a good product - but too expensive for what you get out of it in the lng run).

Adding drywall in the stud bays wold have helped a lot as well.......

Caulking the stud bay was pretty much a waste of resources - better to just caulk the drywall seams..........

I don't see - with your ceiling open like it is - how you gained much of anything with what you have done........

Rod
 
thanks rod,

Appreciate the advice.
a local guy who does nothing but soundproofing for the last 20 plus
years suggested the acoustic caulking as part of a list of other suggestions.

the quiet rock is supposed to serve in effect as a decoupleing membrane with it's viselastic layer in the middle. I have to say it was a pain to install
I would probably use conventional rock with green glue if i were to do it again.

With a 6 by 12 room, building another room inside was not an option.

I was hoping to use the open cieling joice bays as an accoustic extension
of the vertical dimension, giving me another 6 '' of virtual height.

So am i correct in understanding this correctly, a sealed four sided box is not going
to keep sound in unless you add the fifth side (cieling) and seal that in also?
This apart from door and window issues of course.
 
That's exactly correct. By leaving the top basically open, you've created a hole the size of your entire room to allow sound out. Fill the cavity with insulation, drywall the ceiling, THEN add the cloud below that.

To steal a quote: " Think of it like an aquarium. It doesn't matter where the hole is or how big it is, you're going to get wet."

Bryan
 
Cool,

thanks bryan,
I was under the mistaken immpression that the exposed ultralight would "soak up" some of the sound.
Speaking if which, i was wondering, if a bass trap absorbs low frequency
energy and the byproduct is heat, does it also keep some of it from escaping outside?
 
zorf said:
Cool,

thanks bryan,
I was under the mistaken immpression that the exposed ultralight would "soak up" some of the sound.
Speaking if which, i was wondering, if a bass trap absorbs low frequency
energy and the byproduct is heat, does it also keep some of it from escaping outside?
Click to expand...

Not to any degree that is measurable. What it's doing is dealing with what is left after everthing that escapes the room has already done that.

As a matter of fact - there was some testing done using the homemade traps Ethan has plans for on his website. The tests were performed at an independant lab with Brian of Green Glue overseeing the tests.

A "before" TL value was established for the wall assembly - the wall was then essentially covered using the setup that Ethan recommends - and the TL value of the wall did not change.

For all intent and purpose - exactly the same sound made it through the wall in either case - but it did tone things down a bit in the chamber itself.

Hope that helped.

Rod
 
Celings and overhead areas are probably the most neglected area when it comes to preventing sound transmission. Many people seem overly worried about the weight of a couple of layers of dry wall. It sounds like you have floor joist overhead which should be adequate to support the weight. You will only loose an inch and it will do much more to reduce sound transmission than filling the spaces with insulation. You have a 7' celing at the present, 6' 11" is not going to make enough difference to be noticeable, but it will be very noticeable from the outside and above. Soundproofing and treating a room are very different issues, unfortunately there isn't any one product that deals effectively with both.
 
thanks Dani,

It's clear to me now that i have to rock the cieling, but at 6' 11" that would not leave much room for additional cieling treatments.

i guess i'll have to live with a live lid.
 
zorf said:
thanks Dani,

It's clear to me now that i have to rock the cieling, but at 6' 11" that would not leave much room for additional cieling treatments.

i guess i'll have to live with a live lid.
Click to expand...
6' 11" is fine, imo. I have a 6' ceiling, and 6-7' which i need to hang treatments from. Luckily i'm only 5' 6", so it doesn't matter a great deal for me, but all my mates will have to duck. :D

With 6'11" the max you will need on your ceiling is 4"(probs be fine with 2"), so that brings it down to 6'7(or 9)", even a light will probably be lower than that. So unless your really tall, or people who will use it are really tall, then it shouldn't matter. Even if it does, you can simply sit down when recording.
 
Yup. 6'11" still leaves you room to do at least 2-3" of cloud and have no issues with anyone but Shaq, etc. You may have to be a little more creative with mic booms for overheads but the difference in the overall sound quality in the room is well worth it.

Bryan
 
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