How-To: Theater or studio acoustic treatments

Have you been yelled at for watching your latest Superbit DVD "too loud" by your mom / dad / child / spouse / neighbor? Tired of having the Tiki-bar TV guys next door in the background of your podcast recording session? In today's how-to we cover tricks to improve your room acoustics for better listening or recording pleasure. Yeah, we know it may seem a little esoteric -- and our own Engadget Podcast could probably take a hint here -- but you'd be surprised at how nice some peace n' quiet actually is.

Treating a room to improve its acoustic properties is a combination of art and science, especially for the home acoustic engineer on a budget. With an unlimited budget, a room can be double walled and covered in commercial acoustic paneling. When trying to improve the acoustics of an existing room, whether for listening pleasure or anger prevention, a smaller budget is more of a challenge.

Every room has different challenges, but if you're building your podcasting studio or improving your home theater the same problems need to be solved. Sound transmission into and from the room needs to be reduced and the room's acoustics are probably less than ideal.

'Acoustic isolation' is trying to reduce sound transmission out of the room. Improving internal acoustics is a matter of reducing sound reverberation. Completely eliminating reverb is not always desired. Even with today's sound processing technology, concert halls are still designed to use natural reverberation to improve sound for live performances.

For today's how-to we're making treatments for an unfinished basement. Finishing out the basement isn't an option at this house, so everything we do needs to be removable when we move out. Our home theater area has a concrete floor, two concrete walls, and two 'walls' that are open. Every surface needs some sort of acoustic treatment.

Often the simplest solution is one of the best. To keep excessive sound from going upstairs, we hung acoustic ceiling tile on the floor studs. Ceiling tile is easy to get and has acoustic ratings. Basic ceiling tile is pretty inexpensive. For about $60 in ceiling tile, we covered the entire ceiling of our home theater area. Rather than hang the tile with a drop frame, we screwed it directly to the floor joists. When we move out, a quick session with the cordless drill will take these down. The tile is pretty fragile, so using washers on the screw heads is advised. For the floor, a thick wool rug makes a great sound damper.

There are plenty of commercial products for sound treatment. Our temporary install is on a budget, so we built some simple portable acoustic panels to help reduce sound transmission and reverb.

To make your own, you'll need the following:

• 3-1/2 inch thick 15 inch wide rolled fiberglass insulation
• Polyester batting
• Lightweight fabric
  
• 1-inch by 3-inch pine boards
• 4-foot by 8-foot 3/16-inch lauan or plywood board
• Liquid nails adhesive
• Tools: saw, hammer, sharp scissors, staple gun.
  

Dow Corning R-13 insulation runs about $10 a roll. It's made to go between wall studs, so it's 15 inches wide. One roll should be enough to make eight to ten panels.

To make five panels, we need ten 48-inch 1x3s, and ten 15-inch 1x3 pieces for a total of seven 8-foot 1x3-inch boards. It's important to get boards that aren't warped. These boards are pretty thin, so it will be fairly annoying but worth the effort. Look down each board from the end to see how warped the board is.

To keep it light and inexpensive, we used lauan plywood made for floor backing. These panels have a smooth finish and are cheap. A four foot by eight foot panel runs about $10.

Just about every hardware store that sells lumber has a panel saw. Save yourself some pain and have them slice the four by eight lauan into 48 inch by 16.5-inch pieces. Most stores don't guarantee their measurements, so keep an eye on them to make sure they get them close enough. Luckily, the cuts don't have to be perfect.

We picked up this not so stylish green fabric off the wally world clearance shelf for $1 a yard.

We cut our 1x3s down using our handy miter saw. Ten 15 inch cuts for then ends and ten 48 inch cuts for the sides.

Nailing the frames together goes quickly. Start with one side, then locate the other side using the 15-inch end pieces to get the spacing correct. Then add the ends last. Finally a couple nails at each corner help connect it all. Wood glue is optional.

Lay the fiberglass out over the frame and cut it to fit. We tried a utility knife first, but scissors worked best. A bit of liquid nails adhesive under each end will keep the fiberglass in position.

We laid out polyester batting over the frame, and cut it with excess to cover the edges of the panels.

We wrapped the whole thing in fabric and stapled the edges. A quick trim and the panel is completed.

To hang our panels, we used some cheap brass hooks at the topmost corners of the panel. These won't take much abuse, but they'll do the job.

Our row of sound panels hung up in the basement. We're still playing around with the spacing, but they definitely improved the acoustics in the room. If you're not into hanging them, add some hinges and you can make a nifty sound barrier disguised as a changing screen.

[Logan @ Apr 4th 2006 7:56PM]

this seems pretty intese though, you could always get those bose (or other high quality) noise canceling headphones and just listen to some chill simon & garfunkel, maybe some mozart... you could have some silence that way also. but for less money.

[James @ Apr 4th 2006 8:04PM]

About how much was the total cost for everything? Im interested in doing something like this but wanna know the cost.

Thanks

[threEchelon @ Apr 4th 2006 8:15PM]

To 1.

Note the following quote:

"if you're building your podcasting studio or improving your home theater"

Headphones have nothing to do with this project.

[rob @ Jan 22nd 2008 1:36AM]

I have to build a small television studio...any comments on how the walls should be constructed?

[VEGA @ Apr 4th 2006 8:17PM]

You got the wrong kind of fiberglass. That pink stuff isn't going to do crap. You need Owens Corning 703 in 2 inch or two 2 inch panels glued together. The STC on the pink stuff is next to nothing. It's for thermal mostly. The acoustical is usually yellow and comes in 2x4x2" sheets. You can also use rock wool which is cheaper but more itchy. None of this will help your bass frequencies, especially in corners. For that you need to make traps. Get " The Master Handbook of Acoustics". It will tell you everything you need to know and more. It's also best to put the wall panels on a rail or track so you can move them around to find the best location for them. The real way to treat a room is by using software, highly tuned baffles and a good ear. Also, actually building the room right. But, you can google " how to treat room acoustics and standing waves" and find a good bunch of info.

[Bob @ Sep 24th 2008 1:57PM]

Six or nine inches of fluffy pink is *way* more effective at 50Hz, 100Hz and 200Hz than any combination of configurations for 701, 703 or 705. Testing pink, 701, 703 and 705 in 3", 6" and 9" thicknesses, A-mounted or 16" off the wall, it is easy to see that, if you're mounting frames to straddle corners, batts of pink R-30 absolutely knock the socks off any of the trendy yellow rectangles being pushed right now. If you're mounting flush to the wall, performance drops off for all the materials, but 9" of 701 or 703 is your best bet. Fluffy pink is almost as effective as 705 there (i.e., not very).

[Matt @ Apr 4th 2006 8:18PM]

Logan: wtf are you talking about?

This seems like a reasonable alternative to some of the higher priced pre-made room treatments. Does seem like a lot of work, but if you have a home workshop, not too bad, I guess. As I live in Manhattan and barely have room for my Milwaukee cordless drill and a few other tools, I will have to rely on other options.

[ben furneaux @ Apr 4th 2006 8:18PM]

i wish i wasnt still in student halls :P

[earthling @ Apr 4th 2006 8:32PM]

Glad you are happy with your results, I want to add a bit more depth to this for people who are considering this sort of project. Sound absorbtion solutions are created by building traps which are tuned for specific frequencies. Sound diffusers are designed to obscure reflections (scatter). Sound proofing is the art of sealing a room, through the use of sealing and absorbtion (energy dissipation)technologies. This article approaches the problem by adding some diffusion and minor absorption solutions (room baffles) which at best completely absorb one range of frequencies but probably are not very effective for anything else and *may* have some characteristics which diffuse the sound but probably not.

Sound architecture is as much *Science* as art.

Consider this: Think of waves (of water) propogating across a beach. When the meet an obstacle (a boat floating out from the beach), some of the wave energy will be dissapated against the obstacle, most will go around it. Now instead of a single frequency of waves coming across that same beach (like you normally see), think of the chaos of waves of every frequency coming into the beach. Some of those waves have periods of more than 50 feet, others as short as half an inch. For any wave that is shorter than the period between the obstacles the sound will just go right between the obstacles (your panels) for anything longer than your panels they will simply overwhelm the panels and go around them, others will reflect off of them. Think again of this beach with all of the chaotic wave activity coming into shore and while those waves may appear chaotic, the result is what you (more or less) are after, together those waves work to create the music you listen to. Adding reflections, absorption, or resonance at any of these frequencies will only cause confusion in the music, and the result can be ugly. I am not saying that your solution makes ugly music :), only that it is easily possible to create a situation where the result is much worse than the problem.

Having the spaced panels like that will at best attenuate a specific narrow range of frequencies, with some of the energy absorbed by the fiberglass, some in the covering, but most of it beating against the wood in the back of the panel and coming out as ugly reflections. Now those ugly reflections may not be a bad thing (diffusion) but they almost certainly are not the right thing either. (unless you were incredibly lucky).

Try this some time, turn up the stereo in one room and then go into an adjoining room and slowly close the door and watch what happens. With even a very small opening in the door the amount of sound that comes through will remain relatively high until the door is actually closed, stuff a towel under the crack of the door and watch how quickly the sound is attenuated. Sound proofing is about sealing a room and creating the right amount of absorption to keep either sound in or out (or both).

Another aspect and probably the most important one in treating a room is controlling room resonance. The cieling tiles you put up probably didn't improve room resonance as the floor joists were probably acting somewhat as a natural diffuser. Adding the floor tiles only creates a minor barrier against sound coming from above (or below depending on perspective) and only for frequencies probably above 150hz or so. Bass will still go right through at the right SPL. What the tiles did for sure was create a uniform surface which will allow reflections to propogate and build creating an opportunity for resonance. Resonance is where waves are trapped at a specific frequency and can actually build in size (volume) creating humps or dips in the wave size at that frequency. Probably because of the open nature of your room this isn't much of a problem but I wanted to point out that sound control is much more complicated than people think.

[Sean @ Apr 4th 2006 8:34PM]

What are the implications of using fiberglass insulation behind a sheet of fabric in a room? Most insulation installations I've see has fiberglass behind wallboard not fabric. Does this pose any health concerns?

[Deluxe @ Apr 4th 2006 8:40PM]

Sean, don't eat it ;).

[jason @ Apr 4th 2006 8:44PM]

#1, noise cancelling headphones put artifacts in the sound, though. Isolation is the way to go. Plus, what good are headphones for jam sessions with a full drum kit and 100-watt class A half stacks?

[jason @ Apr 4th 2006 8:48PM]

This is also good if you don't want a bunch of sound bouncing every which way in the room. *shudders from playing @ venues with tin stage backdrops!*

[VEGA @ Apr 4th 2006 8:52PM]

Sound travels differently when hitting different objects. It reflects off flat surfaces. It gets absorbed by others. Sound is energy. It is the movement of air particles at certain frequencies. In order to stop certain frequencies, the material needs to stop the sound's energy by fully or partially absorbing it. Which also produces a certain amount of heat (small amount). This is too big of a subject to discuss here really, but, the biggest reason room acoustics suck is because of standing waves. This is when the sound coming out of you front speakers reflects off a nearby surfaces and gets combined back in with the original signal, but delayed. By the time this reflected signal gets back to your ear, it is out of phase. It effectively comb filters your original signal because if one frequency is in phase, and another of the same frequency(reflected) is out of phase, they cancel each other out. With this affect, things sound tinny, lot's of high end, too much low end, dead spots in the room, etc. Bass usually builds up in corners as well. That's why you need traps for those. Fiberglass by itself can't effectively absorb frequencies 500HZ and below. It's absorption works on a curve. The bass frequencies are really important too, because they are heard and felt more than the high frequencies.

[Spooch @ Apr 4th 2006 8:56PM]

HA! at fisrts glance, I thought the picture showed NAPALM!

Looks like a days work. I tried to do the egg cartons on the wall gig, worked ok. The work load seem like the same, because getting all the cartons, and sticking the on the wall, getting the to fit. tedious job.

Thats why I have made best friends with my lovely bose, noise canceling audiophones aswell.

Spooch Out.

[Tomba @ Apr 4th 2006 8:57PM]

Nice One.

I have simmilar pannels at my home studio. They work rather well. Another use for the pink panther insulation is to leave it in its plastic tubes, Cover it with something nice and place them in the corners of your room standing upright. This will help with some of the nodal frequencys in the room wich always terminate in corners.


Peace out, T

[BobbyW @ Apr 4th 2006 8:58PM]

The first thing I thought when I saw the pic with this post: pizza. Hmmm. Pizza.

[VEGA @ Apr 4th 2006 8:59PM]

I actually trained for a certification at the Owens Corning plant in Ohio. Their isolation and reverb chambers are friggin' awesome. Their statement on fiberglass health is that the stuff isn't absorbed by the body. It passes right through. Of course, there is no telling what rats and other things have been on the fiberglass in storage. I have crawled through the stuff in attics many times working in Home Automation and A/V installation. It itches, and on a hot day you can feel pretty choked up. Especially in Atlanta. But, no long term affects I've noticed. Can't be any worse than Slpenda.

[Peter Kirn @ Apr 4th 2006 10:01PM]

You know, if you're looking for an inexpensive sound treatment that actually works, the Auralex stuff is great. For a few hundred bucks (and no power tools required) you can get a small room treatment. The egg cartons do jack, in my experience. For vocal recording, I still like the closet full o' laundry / blankets trick.

[Murray @ Apr 4th 2006 10:11PM]

VEGA has it exactly right. This kind of treatment is actually going to make things worse in most rooms. (It will reduce some of the high frequencies and not affect the low-frequency standing waves.) The room will sound more "dead", but will not flatten out the room's acoustical response.

I'm sure that Will thought he was helping everyone out. But articles like this only contribute to the acoustical folklore. Much like 1" foam, cardboard eggcrates, etc.

Here's a forum with lots of good advice:
http://www.musicplayer.com/cgi-bin/ultimatebb.cgi?/ubb/forum/f/26.html

[Will O'Brien @ Apr 4th 2006 10:39PM]

Thanks for the comments guys!

It's not the 'wrong' kind of fiberglass. 703 just isn't readily available, so I went with the R13. It's a great place to start. If this was a permanent install, I'd have bass traps and isolated inner walls, ceiling and irregular surfaces.

These treatments certianly don't cause acoustic problems. They may not be appropriate for evey install, but to reduce sound reflections in a less than ideal environment they certainly helped.

[soundboy64 @ Apr 4th 2006 11:03PM]

Large cylinders filled with cement work well for soaking up excess bass frequencies too...

[eric @ Apr 4th 2006 11:08PM]

The comments on standing waves, isolation, absorption, and diffusion are for the most part correct. Definitely look at the "Master Handbook of Acoustics" like VEGA said if you want more info. Brief primer on acoustics follows:

Isolation - This refers to how easily acoustic energy is transfered between one area and another. Building materials (like gypsum board and windows) frequently have an STC (Sound Transmission Class) rating in dB (decibels) of reduction. When isolating a space from another space, the weakest link theory prevails, as a small air gap 1% of the area of a wall will easily let 50% of the sound through. For this reason, tight construction tolerances and lots of caulk are used when building a sound proof room that is well isolated from another space. Most materials with high STC ratings are things with lots of mass. Thick gypsum boards, thick metal, poured concrete, etc. The mass helps these materials reflect the acoustic energy rather than letting it pass through them (although some materials like gypsum boards have some absorbent characteristics also).

How a room sounds - There are two main things which effect the way a room 'sounds' or the 'character' that a room imparts on any sound created within its borders. Standing waves, and Reverberation time. Standing waves are created by a circular (or back and forth path) which causes a fundamental frequency and all of its harmonics to build up. They make areas of the room sound different from each other, and raise the reverberation time for particular frequencies. Reverberation coupled with the early reflections give the listener a feeling of how large a space is, and also impart some color to the sound. The primary tools used to control these are diffusion and absorption.

Absorption - This is what is covered in this article. Similar to isolation, you want fairly dense materials usually 4#-8#/cubic foot. Usually semi-rigid fiberglass (Owens Corning 703 or 705) or rockwool is used, and it is available in 2'x4' panels. The 'fluffy' stuff that this article uses will work, but because of the lack of density it will not be as effective at absorbing low frequencies unless they are used in a very thick (18") application. The more dense materials that are only 3" or 4" thick can faithfully absorb down to 125Hz.

Another type of absorber is sometimes referred to as a pressure, or resonating absorber. They are tuned to a specific range of frequencies. There are different configurations, but the general principle is to place them on a boundary of the room where the pressure is highest and that energy will resonate these absorbers, and the resonant energy is then absorbed by absorbent material inside the resonant cavity (usually the same semi-rigid fiberglass or rockwool used for the other absorbers).

By placing these absorbers in key areas of a room, you can reduce the prevalence of standing waves and use the frequency tuned absorbers to reduce the reverberation time of frequencies which have longer reverberation times, making the room sound more natural. Finally, when spaced out, absorbers can actually aid in diffusion.

Diffusion - There are many types of diffusers, Quadratic, parabolic, etc. The general principle is to send the sound in random directions so that standing waves never have an opportunity to develop, and obvious reflections from an offensive surface are not so hideous. In general, the more diffuse the sound field, the more similar the room will sound in different locations, which is especially important if multiple people will be enjoying music or a movie in a room.


So, this article did an outstanding job of demonstrating that with a few dollars and some grunt work it is possible to change the acoustics of a room. Isolation is typically the most expensive and time consuming to attain, and you should not be eluded that hanging small panels of absorbent material will reduce the amount of sound transmitted into the rest of your house. You can however reduce the reverberation time by introducing absorbent materials. As a general rule, use more dense, thick materials so that you will be absorbing the entire audio spectrum evenly. If you staple up a bunch of carpet the room will sound muddy and horrible because the carpet is simply not thick enough to absorb low frequencies.

Good luck, and if you want to learn more, definitely pick up the "Master Handbook of Acoustics" by Alton Everest.

[jc @ Apr 5th 2006 1:52AM]

Come on, didn't any of you guys see Hustle n' Flow? It's all about the mcdonalds drink holders stapled to the walls. JEEZ!

[hans @ Apr 5th 2006 2:13AM]

Have you considered using homasote sound barrier instead? It is cheap when you buy the non-commerical applicaiton type. It smells a bit funky though. It is basically compressed cardboard with great sound barrier qualities (not sure about how well it deals with reflection though.

[submachine @ Apr 5th 2006 4:24AM]

It's a lot easier to get one of these - VocalBooth.com, WhisperRoom.com - they not only keep inside sound from going out, but outside sound from coming in.

[Martin Jones @ Apr 5th 2006 5:34AM]

My site http://www.hightechhomemag.com has some tips for improving the experience you get from your home cinema (for once you guys have all finished soundproofing)
All the tips are things you can do yourself without spending a penny.

[Jon @ Apr 5th 2006 8:42AM]

Just a comment regarding the health effects of being exposed to Fiberglass:

Fiberglass fibers do not pose any long term health effects due to inhalation. Most fibers are filtered out through your respiratory system, and any fibers that do make it to your lungs will dissolve (unlike asbestos, which causes scar tissue to build up around the fibers). So while handling fiberglass might cause irritation, sneezing, or other similar symptoms, there are no long term health effects caused by handling or being exposed to it. People working in the plants that manufacture this material are exposed to large amounts of it for 12+ hours at a time without any ill effects.

One exception to note is that burning fiberglass can pose a hazard. Fiberglass does contain small amounts of Formaldehyde (which was recently reclassified as a carcinogen) as well as several other chemicals, including ammonia. The smoke from burned fiberglass (just like smoke from most other materials) can certainly be harmful to your health.

[Justin @ Apr 5th 2006 9:10AM]

How about keeping sound, particularly bass out of a room? I can hear anything my downstairs neighbor does. Music, TV, even talking sometimes. It seems the wooden floorboards amplify everything. Is there some sort of treatment I could use on the floors to dampen or block the sound, particularly the bass? It would be nice to sleep through the night. (and yes I have already talked to her. sometimes she isn't even playing things loudly, but I can still hear it).

[CiXel @ Apr 5th 2006 10:35AM]

While not really acoustically rated ideally for this purpose, the pink stuff will work MUCH better if you put the paper side TOWARDS the fabric. It may seem counterintuitive, but it will act as a better overall sound absorbsion panel without sucking out ALL the highs and nothing else.

[warrenpeace� @ Apr 5th 2006 10:54AM]

Damn, wish I had my neighbors email address. Those jerks would likely be too lazy.

[matt20102 @ Apr 5th 2006 1:17PM]

The thing to remember with this kind of project is that it is not meant as isolation or soundproofing. With two rigid walls (concrete) and two open "walls," you essentially have a room that is 4 concrete walls spaced apart by the approximate wavelength of signals in the very low frequency range- 20Hz to 50Hz. Most mics used in podcasting will only have a usable frequency response down to ~75Hz. As such, standing low-frequency waves wouldn't be much of a problem in this situation. Even then, how much energy in the low end of the audio spectrum is produced in a podcasting situation anyway?

A few of the panels closely-spaced together and placed behind the mic will have a reasonably good effect on noise bleed-through for voice micing (from rear noise sources, anyway). Would it be appropriate for recording or broadcast studio use? no, nor was it meant to be. Good project.

If you want proof that these are a reasonable solution, look to any photos or video of old recording studios (1940's to 1960's)- they used panels like this frequently to control bleed through between various musicians' mics.

[Rich @ Apr 5th 2006 1:46PM]

My friend (who owns a studio) and I built some baffles from some old TV show sets. The walls of TV show sets are perfect for this purpose. We didn't fill them, but we only use them to block sound away from mics. We sort of built a little cubicle around a drum kit. It works pretty well from separating the drum mics from the guitar amp and bass amp mics for live recording. It's true though that any gaps will let the sound out.

I just pulled "The Master Handbook of Acoustics" out from the library. It has a whole section on sound treatment. I just wish we had a nice rectangular room to work with... Oh well.

[scot @ Apr 5th 2006 3:31PM]

Nothing in this article is about soundproofing ("acoustic isolation"). If you want to "soundproof" a room, without going to the expense of a suspended room, simply seal all the gaps around the windows and walls (and in the woodwork, if any).

To acoustically treat a room such as a basement with parallel concrete walls and floor, that is to make it an acceptable lounge room, I would reccommend:

- heavy drapes on the entire surface of at least one wall (two walls might deaden it too much)
- carpet on the floor
- soft furnishings

that's probably enough to get acceptable listening results.

[eatSHROOMS @ Apr 5th 2006 5:33PM]

i live in the basement(unfinished, no celing) and whenever anyone is upstairs, they can hear absolutely everything down here. what cheap products/solution would you recommend to fix this problem?

[VEGA @ Apr 5th 2006 6:06PM]

Top things you can do to get great sound in a room (both Theater and Studio):

- For guitar amps; use a THD Hotplate. It's a power attenuater. Crank your amp to get harmonics, stays at low volume. Great with Marshalls and Bogners.
- Make sure your speakers are placed right. Check the manufacturer for placement. Most should be away from the back of the wall at least a couple of feet so three is no resonance coupling. Front ported speakers can go a little closer. Use a piece of 703 wrapped in fabric and sit your speaker on it to decouple it from surfaces. Your best listening area is in a equilateral triangle setup. If you soffit mount them, you must treat the cavity.
- Heavy fabric drapes, velvet or equivalent, are good for cutting down window leakage. You can also make a heavy batted wool or horsehair drape behind that.
- If you have an option to do it, build room within a room. Anything that is as close to air tight as possible and decoupled from the outside surfaces will cut sound dramatically. Of course, not everyone can do this.
- Those old cubicle dividers, the ones that are modular and fabric covered, are pretty good at isolating things. They can be modified for better absorption. Pretty cheap at office supply reclaimers.
- DYNAMAT I have heard from numerous people that this stuff rocks. It cuts sound down like you wouldn't believe. It's also expensive. So...
- Doors leak a lot of sound. If you have the option, build your own and make sure it is dense as possible (sand filled) and is sealed on all sides so nothing leaks in.
- Put you A/V equipment in a cabinet with a low speed fan to cut out equipment noise.

[VEGA @ Apr 5th 2006 6:14PM]

http://www.dynamat.com/products_architectural_dynil.html

[SideSwipe @ Apr 5th 2006 6:26PM]

For a great looking treatment (instead of the fabric), you could consider using a perforated metal sheet. It costs a bit more but looks hella cool.

As others have said, the pink stuff is more for heat; while it will do the trick for sound, there's other options just as cheap and more effective.

[Ryan @ Apr 5th 2006 8:15PM]

I don't mean to pick on you scot, but simply sealing all gaps around windows and walls is not nearly enough to "soundproof" a room. Windows typically have low STCs, no matter how well they are sealed and the wall construction plays a large role in how well it blocks sound from being transmitted. Whether or not there are resilient channels, how many layers of gypsum board are used, the airspace in the wall, whether or not sound batt insulation is used, the pattern of the studs, how the studs are attached to the wall, etc. can all have a dramatic influence on how much sound is actually transmitted into/out of the room.

In addition, carpet and soft furnishings (along with people) will help increase the amount of absorption, but heavy drapes will only provide absorption of any significance at higher frequencies and will do virtually nothing at lower frequencies, which could lead to some nasty flutter echoes. When I'm designing spaces like a home theater, I like to have a front wall that is partially parallel to the back wall and partially splayed on the left and right to reduce specular reflections without a lot of treatment. I also like to place absorptive and diffusive tiles on the back walls, side walls, and ceiling.

One more thing, just to correct something stated in the article, acoustic tiles without a stiff backing (like most acoustic ceiling tiles) do not keep sound from being transmitted out of the room. Actually a typical ceiling tile has a very low TL. Also, screwing ceiling tile directly to the floor joists reduces their effectiveness somewhat because the 4" or so airspace between the ceiling tile grid and the actual ceiling is important part of the absorption mechanism.

[Schleeb @ May 14th 2006 8:41PM]

Seems to be a few experts here... I have a question about panels as well. I have an old king size memory foam mattress that I was considering throwing out. It's not a full mattress just a 1 1/2" pad of that material. Since I'm now planning my basement home theater I was wondering if this stuff would be worth keeping to use as the basis for some corner bass panels? It seems like it would make an excellent sound absorption material. I'd just glue it to some a panel and cover it with some decorative fabric. Question 2 would be what would be the best type of panel material to glue it to. I don't think plywood would work very good, at least acoustically, that is. So what's a good material to use? How about some cement subflooring panels maybe? Just looking for ideas.

[ScreamingPirhana @ Oct 12th 2008 2:28PM]

The kind of pad you are thinking about using is dangerous, highly flammable. It's what caused that horrific nightclub fire (in ohio??) that killed all those people and got the club owner in hot water (sorry) for trying to cut corners. I wouldn't want something like that on the walls of my studio...

[Rick @ Jul 23rd 2006 2:11PM]

. . . ditto that about the memory form question. I have an old Queen (har har, insert joke here) I was going to throw out . . perhaps turn it into a few choice panels?? This inquiring mind wants to know . . .

[Hussy @ Sep 4th 2006 2:11PM]

Auralex Lenrd Bass Traps. They are pricey, but will definitely make the improvement that you are all looking for as far as lower frequencies.

p.s. VEGA is correct, the wrapped "pink" fiberglass may help a tiny bit, but that technique goes hand in hand with the heavy blankets, egg carton (etc.) type methods. They do little to almost nothing. There is a plethora of knowledge all over the internet. Take some time to research acoustics. You won't regret it.

you can also go to www.homerecording.com/bbs
LOTS and LOTS of awesome information on there.

Good luck.

[Bill Jenkins @ Jan 23rd 2009 11:54PM]

Jeez...it's incredible how wrong some people can be. Auralex "bass traps" are as useful as egg cartons for absorbing bass. Thick panels of pink insulation are far more effective. Not just far more effective. They are very effective, whereas the Auralex LENRD things are not effective in the least.

SERIOUSLY, if you don't know what you're talking about, don't post stuff online. You're just making it harder to stop the spread of false information.

[Mike @ Sep 9th 2006 11:20PM]

Try this: Wave your fist frantically in the air, with lots of energy. Many foot/pouns of energy, in fact. Do you hear any sound? No. That's because it's "acoustic energy" in air.
Now lightly tap your little finger's fingernail on a table, preferably a wood and hollow one. Hear the sound? That's caused by "vibration."
The reason you hear your neighbor's bass guitar, home theater or the train a mile away is due to vibration, not sound energy per se. Isolate the source, typically one that couples with wood, concrete, or ?, and you'll fix the acoustic problem. You could have R-31 two feet thick on the walls and the bass will still come through. Put your neighbor's speakers on a foam pad (vs. directly on the floor) and your problem will be (90%) solved.

[Yoder7707 @ Nov 6th 2006 12:00PM]

Help!! My fiancee I are having our favorite live duo play at our wedding reception however the hall has terrible acoustics. Does anyone have any ideas on what to do temporarily fix this problem without drilling holes in the walls? Thanks in advance for your help!

[Melonhead @ Feb 23rd 2007 5:37PM]

I would like to say that this is a great idea and I will probably use it. I travel a lot, so my laptop and recording gear travel with me and i need something more portable than an "at home" studio. This is perfect. All im looking for is something to make the room dead, probably wont get the effectiveness of a small studio set up, but this will work just fine.