Sound Absorption... HELP?

OK, here's a fourth opinion, coming from someone who has designed and had built two studios after tearing off drywall to bare studs: absorption will do very little to provide transmission loss between rooms. Some, yes, but that some isn't much. If you covered the entire ceiling with 4" thick rigid fiberglass, it might be about as good as a layer of drywall, but it would cost a lot more (it would greatly improve acoustics inside the studio however). Anything short of that, I would not be expecting much.

Let's try some math: 4" of rigid fiberglass has an absorption coefficient of less than 0.75 at frequencies less than 125Hz. How much is hard to say; the published numbers include edge effects and are measured in a reverberation chamber, you are trying to stop sound that is an octave lower, etc. But let's say 0.75 is accurate for transmission loss (which it probably isn't). dB = 20 * log (1 - 0.75) = -12dB. That's absolute best case scenario of covering your entire ceiling with 4" of rigid fiberglass.

So if your existing ceiling has transmission loss of say 40dB, now you have 52dB. The kick drum hits will probably sound at least at 50dB above. That's not really a problem in the daytime for people that aren't bothered easily, but maybe your neighbor will be one of those type that likes to complain. In any event, it will be too loud for sleepytime.

As for hanging panels or partially covering the ceiling, try this experiment: crank some tune with pumpin' bass through your sub. Get a pair of earmuffs, or maybe some headphones that aren't plugged in. Hold them about 1" off of your ears, and compare that sound with the earmuffs off. Hear much difference in the low end? That's about what absorption will get you.

Since you are mainly concerned with transmission upwards, what mainly matters is how the ceiling and ceiling/wall joints are constructed and what the floor material above is. You cannot change either of those, so you'll just have to see how bad it is.

The plexiglass shields are for live use; they keep other musicians from getting deafened by nearby loud instruments. They really only need be effective in the 1kHz and up range, because we aren't particularly bothered by loud low-frequency sounds; it's the high-mids to highs that are especially damaging to hearing. A plexi shield will do nothing to increase transmission loss of low frequencies upwards in a studio.
 
3 years ago I built 5 bass traps via ethan winers web site in my 40x30 live room

Ok, you built 5 bass traps for your 40x30 live room?:eek:Hmmm, ok, lets move on...
we mixed in a concrete 15x15 box covered in the corners and all the direct reflecting spots with OC-703 rigid fiberglass

Hmmmm, ok, now you are saying you not ONLY built 5 bass traps, but also had 703 "in the corners"...(ie...bass traps. which if were ALL IN THE CORNERS would amount to ...lets figure this out....in the vertical corners...that would be four MORE bass traps....and in the wall/ceiling intersections...that would ALSO be 4 MORE bass traps...for a total of EIGHT more. Four, at a nominal 96" height, and four...FIFTEEN FEET LONG at the ceiling.:eek: Good for you.

Ok, gottcha, you had all the low frequency modal termination intersections covered..in your concrete 15x15 mixing box...

and all the direct reflecting spots with OC-703 rigid fiberglass
:cool: sounds like you knew what you were doing.

We had a budget at that point
I would think you did, considring you are 19, with a 30x40 live room and a 15x15 concrete control room...both treated "fairly" intuitively.

I am going to Berklee next year and moving into the bottom apartment in a three story Building in Brighton.
Cool. Berkley is a cool place for a 19 year old to exploit the wonders of knowlege.

The drummer is moving in with me and would like to be able to practice at reasonable hours. I'm sure that playing during the day will be fine with the neighbors but I would like to tone down on as much of the noise as possible.

Ahhh yes. Drummers. Apartments. I smell a challange coming.:)

Unfortunately I believe the building lays on the end of two identical connected Apartment complexes owned by different landlords.

I knew it was coming.:rolleyes:
Yes, that is unfortunate. :(

Luckily the walls of his room only touch other walls in our apartment or the outside of the building

Lets see, thats "one" for the negative team and "one" for the positive. :D Its neck and neck folks....ok...

So basically we have no side neighbors.

Whoa!..
the positive is pulling ahead.:p

We are thinking about converting his room into a fo-drum booth

fo-drum????:confused: Never heard that term before. Is that sort of a "quasi"
drum room?

Obviously its not a real booth because we can't do anything permanent like double the drywall or build a room with in a room.
Yes, obviously. Ok thats the challange, right?

We do have a decent amount of money to spend though.
Define "decent amount" vs what you have in mind. See below.:)

I'm no genius when it comes to acoustics but I believe that the most cost effective solution would be to try to get rid of most of the low frequencies via bass traps.

Your belief is incorrect. Absorption only reduces REFLECTION back into the space. Just because an absorption material achieves this to a greater or lesser degree, does NOT mean the energy/pressure from IMPACT sounds on boundary surfaces behind them have been "absorbed".

I figure if I build a riser for the drums that is just a 5x6x1 sealed reverberating box and place 3" 703 about half way between the top and bottom that should do a decent amount.Essentially it would be a huge bass trap for him to play on.
No, essentially, it would ba a huge drum.

In essence, what you are suggesting is to INCREASE the size of a sound generating membrane. Impact noise from the drums will actually excite the membrane and INCREASE the amplitude via resonace of the box OUTWARD.
This is EXACTLY how stages work.

A "riser" soulution in this context should be a SOLID mass. ie..a concrete slab...which considering you are on a ground floor, in all probability IS
concrete.:)
The box would be raised above the floor with rubber feet.
Yes, decoupling is wise.

Although, to eleminate structural transmission, decoupling the mass is the correct way to go, but "properly" decoupling a slab would require accurate calculations to determine the "compression" ratio for pads such as Sylomer or neoprene, as the correct compression is what makes this type of decoupling work. Also, if neoprene is used, you need to know the "duro"(hardness)
rating. Sylomer is already color coded for each rating.

However, considering you said:
I AM NOT GOING TO BUILD ANYTHING IN THE FUCKING APARTMENT.
well, I guess the riser idea is out.:rolleyes:


My third Idea is to hang 3" 703 about half a foot from the ceiling
For what? Are you recording the drums? Yes, this will help with reflections, but do nothing for transmission loss through the ceiling.

I believe the room is a 15x20 and I know that the drummer will be willing to give up at least half of it for sound absorption
Thats a LOT of 703. How deep are your pockets?
And after you've spent your wad, what garuntee do you have that it will do the trick.;)

Do I need the drum riser or is it kind of useless with the other traps and the dropped ceiling?
If the existing floor is concrete, purchase a 6x6 area of this type material with a plywood or MDF subfloor material placed on top. However, this will do nothing for impact
sound that reaches room boundarys via the air.

http://www.acousticbooth-studiobox.com/acoustic_insulation.php

Does someone have a completely different idea that may work better?
1.
Tell your drummer to buy a set of practice pads.
2.
you'd really be better off getting some good electronic drums, some isolation headphones
3. Let your drummer figure it out.
4. Tell him to play quietly.
5 Ask your neighbors to ignor it if they complain or they are imagining it.
6. Rent a rehearsal room.
7. Tell your drummer to move.
8. Trust the bricks. Although I'm a little confused by this..
NO SIDE NEIGHBORS.
:confused:
9. Accept this..
I KNOW I CAN NOT ISOLATE THE DRUMS!

10
Anyways, try your idea as long as it's safe, and let us know what happens.
:D
think you're pretty much on track. I would not seal the back of the bass traps you have.
:eek::rolleyes: riiiiiiiiiiiiiiight.:rolleyes: yessssereee. good one apl.:rolleyes: That'll really wrap this one up. Say, did you ever build your "heat your house with your dryer duct" project?:rolleyes:




btw..
We're talking about acoustic drums, buddy.
Now were gettin down to brass tacks.;)
Supercreep you have no desire to help.
CLEARLY. Stay away from this thread asshole.


Hmmm, Supercreep gave the best advice possible and hes an asshole? geeeezus kid. What part of "acoustic drums"/apartment don't you understand? fuck, I don't think Berkley's gonna
help ya:rolleyes:

But this might.
http://www.acousticbooth-studiobox.com/acoustic_insulation.php












but give me a brake

Good luck.
:)
 
Tell your drummer to buy a set of practice pads.

That is all, dismissed!!

Seriously, that will probably cost you just as much as any room treatment would and will actually solve the problem. That sounds like the best bet at the cost of some of the drums "feeling".

Does he play drums at Berkeley? Then he can practice drums in their rehearsal spaces which I'm sure there should be plenty.

Good luck!
 
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