Room Accoustics and Soundproofing

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It's rarely the material choice itself so much as the way you put together the whole package that governs the isolation you can achieve between spaces. The knid of product you've linked to looks useful for certain properties, but it's not necessary to achieving great isolation. I'm an architect, and do get to specify this sort of thing regularly. Once you start aiming much over 40dB Rw then it's easy to destroy the performance by careless construction - it all goes to pot if you end up with unintended services penetrations, poor sealing or offcuts bridging the cavity(ies). On the other hand - it's quite straightforward to achieve 65dB+ of isolation with regular sheetrock and just a little care.

That comes from careful design and even more importantly, careful contruction. All major plasterboard/sheetrock suppliers have products optimised for acoustic control (ie increased density) or you can just add extra mass via more layers of regular sheetrock, but for high performance the use of resilient hangars, staggered/double stud consturction and internal damping (mineral fibre to damp the interstitial space(s) becomes much more critical than the board choice.

Have a good read of a book like F. Alton Everest's 'Master Handbook of Acoustics'. It's clearly and concisely written, and buying a copy will be a lot cheaper than making uninformed construction choices.

HTH!
 
Often the best sound insulation is also the best temperature insulation ... if your walls are not already insulated for heat/cold, do that first = saves $$ bucks on gas / electric bills, too. After your walls & ceiling are thermally insulated, then add the acoustic sound insulation as required.

Martin Clark: " ... It's rarely the material choice itself so much as the way you put together the whole package that governs the isolation you can achieve between spaces. ... you can just add extra mass via more layers of regular sheetrock, but for high performance the use of resilient hangars, staggered/double stud consturction and internal damping (mineral fibre to damp the interstitial space(s) becomes much more critical than the board choice. ..."

What he said. ... Room positioning of the speakers is important initially as well. A decent gap between speakers and walls can do wonders for any neighbors' complaints. Carpets on the floors help too as do curtins on the windows.
 
Thanks guys. Great info.

I got all these points and the key points from all what I can gather are isolation and density to absorb sound. The density is what attracted me to magnesiacore for the wall, ceiling and floor. Then "green glue" (accoustic glue/caulk) would be used to provide isolation between the much denser magnesiacore which I would apply over the existing drywall (walls and celing) and also over the concrete floor. Kind of a creating a floating dense mass over the green glue as the isolation. Makingover just the interior of the existing room.

I think this should work for the extisting room in the basement without building the room over from scratch. Making it more soundproof. (DIY project and I don't want to make too much of a mess or get trades involved or tear any thing down to rebuild walls and ceilings)

I have to work on the door and vent openings somehow.
 
One thing you might try before you make anything permanent ... if you have access to them:

Those portable, temproary walls that make cubicles in office space, usually cheap when used and make for good adjustable sound deadening panels ... move 'em around until you get the room response you really like, then go to work with the hammer and nails ... a cheap trick often used to "tune up" small auditoriums, prior to the installation of the final mix ... :smash:
 
Just a quick note that acoustic behaviour inside a room, and the isolation between that room and the bounding spaces are two entirely different problems!

HiSix -About doors - presumably you want to improve the isolation the door offers. Two keys to achieving this: mass, and lip seals. Domestic internal doors are often little more than two ply/masonite skins over corrugated cardboard core - useless for your purposes, they only offer Rw of 18-20dB. Substituting a solid-core timber door will help, and one economical way we spec commercially is to make all doors out of fire-door blanks (since these have solid chipboard or flaxboard cores); these are little more expensive than a 'regular' doorleaf, but will give you Rw 30-32dB when used with lip seals (brush, batwing or wiper type). 44mm (1-7/8ths) leaf thickness is good, 54mm (2-1/8") is better. Ensure the door is hung with minimal clearances all around, too.

This is certainly cheaper than going to a supplier and asking for an 'acoustic' door - which will be the same damn thing with a much increased price tag! If you really want/need 40dB+ performance though you must expect to pay for it...
 
For the door, (since it luckally opens into the room) I plan to reinforce the hinges (say a piano hinge) and apply a sheet of magnesiacore over the existing door that is a couple of inches larger than the door. This will give me a good lip to work with that I can apply a foam gasket to seal when the door closes.

I will use the green glue and some threw bolts with rubber washers to bolt the panel to the existing light weight door. I think this will work to add mass and isolation to the door opening and create a seal.
 
I agree that Everest’s book is a must. I am not sure what yours magnesiacore is but I do not like high density or hard material for its sound. I have concrete floor in my room because I couldn’t do suspended wood. Halve of my floor is covered with carpet and it is OK. But if you cover walls and ceiling with hard boards you will create a bunker. There are different opinions on walls: some like it light and flexible for maximum bass absorption, I have 5/8 gypsum boards on rather stiff frame (2x6 16” on center) for bass energy preservation. I treated room corners to absorb standing bass waves only. Gypsum boards, gypsum stucco or wood that’s not too hard is my choice for surface material. Any hard surface like glass, ceramic tiles, pergo, oak etc should be avoided. Sound proofing is another matter but adding little mass will not solve the problem. In my opinion, if you really need sound insulation, double studs walls (and ceiling) of some kind is the only way to go. All my walls are outside walls. From heavy but single stud walls I have about 45 dB attenuation; I do not need more as I live on a quiet street. I could hear birds and frogs through sealed single solid core door - a second solid core door was necessary to drop the noise level below 20 dB. One of my doors is a garage door but it is framed like a wall and triple sealed, it is hung on industrial hinges. My window and AC has a solid core sealed shutter also. The ceiling plaster boards are hanging on 2x8s that are not connected to the roof. Room shape, dimensions and acoustic treatment is another chapter.
http://gallery.audioasylum.com/cgi/view.mpl?UserImages=21150&session=
I am not an acoustical engineer, my room is totally DIY - when building it I was more concerned about sound than looks. The room and speakers are the most important part of audio system. By doing it yourself you can go beyond commercial solutions.
Marek
 
Martin Clark knows what he is talking about. I would like to reemphasize the two aspects of ROOM acoustics versus ISOLATION. The two can become related, though, in that the better you isolate the space, the more you tend to have buildup of low-frequency energy inside the space. The higher frequencies are easily treated with acoustic panel, foam, or fiberglass-based absorbers. But the low frequencies can be harder to control. Half-wave tube traps work extremely well, but are quite frequency specific. (Don't shell out $150 for them, they're simple to make!) Otherwise, do something to kill all the corners, or even the entire corner edges.

Generally, for a recording studio, you want some "soundplay" from the room. Among other things, generally you want smooth frequency response and a controlled reverberation time. But, if you're dealing with smaller than 1 or 2 thousand cubic feet, I would not try to achieve any ambiance - just deaden the whole thing and add effects digitally. In my experience it is just way too much trouble (being a perfectionist) to tame those lower room modes, despite good room dimensions.

Also, when you seal up a room real well and have bodies and hot equipment, ventilation becomes a must. What I did was to buy a $100 air conditioner, and proceeded to build 4 mufflers. Thus, each vent (in and out) had a muffler on both the inside and out. Each muffler was about 2'x2'x6", with a folded air pathway inside formed from staggered baffles. Each muffler gave about 10 dB of isolation, thus each vent had 20 db of isolation - note that this is only for the small vent area, not the overall room isolation. This was an experiment, and more complex ones should give even better results, but much better than a six inch hole! Making the baffles was a lot of work, but quite effective. Martin, what other alternatives are there for something like that?
 
Originally posted by adrome
what other alternatives are there for something like that?

Er, you built it ;)

Fixed installations use inline attenuators sealed to the partitions they penetrate, comes at a price though. DIY labyrinths as you describe work well though - put at least one bend in, so there's no straight-through path, and lag the walls with something like mineral wool. You don't have to fill the space though - it's exactly like lining a transmission line speaker...

I've used the same idea on a Primary school which wanted natural ventilation (no mech vent)...under a military airfield flightpath(!). Permanent vents under the fixed windows fed a labyrinth under the cill, about 5' path length lined with mineral wool. Dirt-cheap, it looked like a regular 'flat' wall lining with a neat louvre/damper below the window cill, and we still got something like 23dB reduction in ambient noise over just opening the windows :)
 
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