Sound Treatment or Soundproofing or Both
So your musical progression has passed the stage of listening to music, to making music, to recording music (or whatever passes for music today). Or you want to upgrade the quality of your YouTube videos. Or the sounds you are getting in your ‘home theater’ are cringe-worthy. The terms Sound Treatment and Soundproofing are not interchangeable. Many people think they refer to the same thing. Nothing could be further from the truth.
- Sound Treatment is the art (Black Magic?) of customizing the acoustics of the room to make the frequency response consistent, and control the types of sound, and the sound reflections inside the room.
- Soundproofing is usually what needs to be done to eliminate external sounds. Sometimes there are also internal sounds that require attention.
There is no definitive ‘One Size Fits All’ guide to Soundproofing or acoustic Sound Treatment. The variables are virtually infinite in both cases. But here are some things that are fairly consistent considerations in all Soundproofing and Sound Treatment applications. I would be very wary of anyone telling me that he/she/it has the only perfect solutions. (Note: I have been installing windows and doors for over 30 years and I would guffaw at anyone suggesting there is only one perfect way to do it–and he knows what it is.)
There is not much point to spending time, effort, and money creating a zippy recording room if the neighbor’s dog barking comes through loud and clear during a drum solo. I suspect that ‘Woof Woof’ does not improve the vocalist’s high notes either. I am not going to spend a lot of time on this because it is not the thrust of the article, but you absolutely need to deal with it before moving on to acoustics.
When you think of ‘noise’ think of weeds. A weed is a plant that you do not want in a particular location. Noise is exactly the same. ‘Woof Woof’ bleeding into your studio is ‘noise’ to you. The ‘Boom-Chukka’ rap anthem you are producing is ‘noise’ to your neighbors. Shooting the dog, or fending off the noise police are very rarely good options. You need to ensure as much ‘noise peace’ as possible. Having a decibel meter you can use to check the noise coming into, or getting out of, the room before and after your soundproofing efforts is an easy way to monitor your progress.
New Construction Sound Treatment–a Purpose-Built Space
This is the best option for your studio because it means you can design exactly what you want and/or need. It also means you have a heck of a lot of money to spend. When designing the building make sure that soundproofing is at the top of the priority list. Build the walls using 2 x 6 studs (at least). ProRox SL 960 Rockwool for insulation instead of fiberglass. Install double 1/2″ drywall with Green Glue sandwiched between. Ensure that the ceiling is well over 8′ (if possible), and soundproofed with Roxul or Cellulose blown-in insulation. Use the same double drywall/Green Glue finish.
For natural light, install skylights instead of windows. (Sound getting through skylights continues straight up, and there are not many dogs ‘Woofing’ on your roof.) The finished skylight chimneys will also help with acoustics because of the extra angles they provide. A well-sealed, or even a double door entrance system is also essential for soundproofing. Keep in mind that you will also need heating or air conditioning. Preferably these units are outside the main studio to remove the possibility of the ‘noise’ from them interfering with your recordings. Ideally most of the noise will remain in the other room.
Re-Purposing: Sound Treating an Existing Space
This is probably the most common option. Almost everyone can find a space to create, or listen to, music–if she/he is determined enough. Garage, basement, spare bedroom. If you have an unfinished space inside the house you can use the ProRox SL 960 Rockwool, double drywall and Green Gluesuggestions. You may also want to add a layer of Mass Loaded Vinyl to the studs before drywall, change your hollow-core door to a solid slab, and seal all of the gaps around the door and between frame and wall.
If the space you choose is finished and you do not want to, or cannot, tear the walls, floors, ceilings apart; add as much mass as possible. 5/8″ drywall is better than 1/2″. The best option is to build a ‘room within a room’ which is simply adding another wall inside the existing ones using isolation clips and hat channel to decouple the new wall from the old wall. Soundproof with ProRox SL 960 Rockwool, double drywall, and Green Glue.
Note: Keep in mind that the extra wall will use up quite a bit of space. For instance: If your room is 12′ x 12′ you have 144 square feet of floor space. By adding a 6 inch wall on all 4 sides you will lose about 24 square feet of floor area. That is around 16% of the room. If you need all of the space you can get, this might not be a viable option.
Note: For more detailed information on either of the above options please read some of our other articles like How to Soundproof a Garage or How to Soundproof a Bathroom. (You can probably ignore the information on making your toilet flush quieter in the ‘Bathroom’ article.)
Sound Treatment–Do I Really Need It?
YES! Get the room acoustics done first–and done to the best of your ability and budget. Because buying all that zippy equipment just to create a sound like 2 cats fighting in a tin garbage can could be depressing. (Unless you like the sound of 2 cats fighting in a tin garbage can.) It is much easier to create great sound when the acoustics are right, than it is to adjust the sound to bad acoustics.
Your microphone, and/or ears, are dealing with two types of sound.
- Direct Sound – travels in a direct (or straight) line from the source so the frequency balance remains pure.
- Reflected Sound – travels randomly around the room reflecting off surfaces like walls, ceilings, and furniture. A very short time later some of these will get to the microphone and/or ears. These sounds will not all arrive at the same time because of the various distances travelled inside the room. Reflected sound can change the original very slightly–but there are enough of them bouncing around and arriving at slightly different times to disrupt the quality of recording or listening.
Sound Treatment–Now You Are Ready
Great acoustics, and therefore great sound, require a lot of space. Your garage, or bedroom, or basement do not qualify–without help.
Saying that recording equipment is only as good as the room it is used in is not exactly correct, but bad acoustics will certainly detract from any efforts you are making–regardless of the quality and cost of your equipment. Your acoustic treatment should produce–as much as possible–a neutral sound balance making the recording transferable. If it sounds great in the studio, you want it to sound great in a different listening environment.
Generally, you are dealing with two types of wall/ceiling/floor acoustic treatments:
- Absorption–Used to absorb energy of the sound wave to dampen the resulting sound reflections. The idea is to eliminate reflected sound so only the pure direct sound is recorded, or heard.
- Diffusion–Used to divert the few remaining reflected sounds and stagger the timing of their return to preserve the room’s natural tone.
The proper combination should enable high quality recording and listening.
Bass TrapsBass Traps are used for sound absorption. They deal with the low frequency energy. These are probably the most important items you are going to install in your studio, so get them done first. And spend the money on good ones. (And no, they do not have anything to do with fishing, which was my first thought.) They are used to absorb low frequency energy (under 500 hertz) that, for some reason, tends to accumulate in the corners of the studio/room. There are two popular designs:
- Resonating Traps are a rigid panel that floats on absorptive material. They only work on small bands of, and at, particular frequencies.
- Absorptive Traps are large amounts of acoustic foam or rigid fiberglass. The mass alone cuts down on low frequency energy.
Both types are usually installed in room corners where you find that low frequency waves collect. Use acoustic foam mounting tape.
Note: Frequency is measured in cycles per second. One hertz equals one cycle per second. Sound frequencies under 500 cycles per second are usually defined as Bass frequencies. For a bit more on frequency and Hertz measurements please go to techterms.com Or if you want way more information than the average person needs you can take a peek at Wikipedia.
Products with sound absorption properties include foam panels and rigid mineral wool (Rockwool). NOT egg cartons. Please see our article on Egg Carton Soundproofing to totally remove that myth from your mind. Make sure your foam is at least 2″ thick. Thinner panels will not do the job properly. These products absorb the energy of the sound wave to dampen the resulting sound reflections by turning it into heat through friction. Two-inch acoustic foam works very well for frequencies above 500 Hz but not very well for bass frequencies. And you do not need to completely cover all of the walls in your studio. Some acoustic experts suggest that 30% – 40% coverage is sufficient. It makes more sense to start in the 30% range–then add more as needed–than to cover 80% and find your room sounds dead.
Absorption, combined with Diffusion also reduces flutter echoes–which are produced by sound bouncing between parallel surfaces. (Note: If–when designing your studio–you can manage to have at least one wall that is not perfectly parallel to another, you have already greatly reduced the chances of flutter echo. The reflected sounds will not be running into each other.) For more on flutter echo please check out acousticsciences.com and acousticfields.com
Now that you have absorbed all of the sound you want to, you need to deal with whatever is left over. This may sound dumb, but you need to have some sounds in the room–otherwise anything you record will sound flat. Diffusion is the answer. Diffusers are designed to divert and disperse the sound wave and stagger the timing of its return to the microphone or ear. They do not rob the sound of energy like absorptive materials. They keep the frequency response more even.
The random shapes you see in diffusers are not there just to appear cute; most of them are the result of mathematical equations. Diffusers are made of hard surfaces–usually wood or plastic. They are more expensive than absorbers. Some people believe you do not need them at all in smaller rooms–others think ‘more is better’. You will have to decide on the type and quality of sound you want to make, or listen to. If you get the absorption part done, you can always add diffusers later.
Now to Get it Done
Now that you have a pretty good idea of what you want to accomplish, you should have a plan detailing where you want to install the product, how much you need, and do you want to spend that kind of money. Drawing by hand might give you a general outline, but you can buy all kinds of 3-D planning programs (from very inexpensive to ‘Wow, I’m an architect’) or you can find free ones like sketchup.com to flesh out your ideas.
Many acoustic product manufacturers offer consultation services. Some even provide free on-line calculators or downloadable apps. (auralax.com; vicoustic.com; primacoustic.com) Once you have an idea of your requirements, I recommend you make use of these options. Once you have all of the product, you can start drawing on the wall (in pencil) following your plan. It is way easier to erase a pencil line than to remove foam that is glued to the wall. Once the room is all laid out and you have counted panels and decided on color combinations (if you opted for colors or designs), you can glue your absorbers to the wall. Even then, I might opt to use removable double sided tape for the first few–specially if you are a visual type of person and want to see what it will look like before making it permanent. Or, more importantly, test the sound quality before making it permanent.
- Use a level–either for your pencil lines or the panels. I am sure that sound waves do not care if things are not perfectly level or plumb but it will save the annoyance of having someone (like me) pointing out your supposed shortcomings.
- Make sure it stays where you put it. I would use spray glue to attach the foam. If you ever want to change it, there will be issues–but having to stick it back on the wall because it fell off may take some of the joy out of your studio.
- Another option for hanging them on the wall are self-impaling clips. These are metal plates that are screwed onto the drywall and the acoustic foam hangs (or is impaled) on them. A word of caution–if you decide to move things you could leave exposed holes in the drywall that will need patching and painting. The clips are available from Auralax or Primacoustics.
Leaving a gap behind rigid absorption panels increases their effectiveness. Also they are considerably heavier than foam. You can hang them from the ceiling, but my preference would be to screw a 1 x 2 board to the wall (screw into the studs), then hang them like you would a picture. If you use a decent piece of wood (like oak), and finish it properly, you can run it the full length of each wall. There will be a 3/4″ space behind anything you put up, you can install hooks anywhere along the board, and you can also hang heavy wooden diffuser panels from them. This also gives you the option of moving panels around without scraping them off the drywall.
It is possible that you do not have to go through all of the measuring, calculating, and deep thinking required for ‘from scratch’ acoustics. Some acoustic product suppliers offer room acoustics in ‘kit’ form giving you the option of starting small and then enhancing your studio by adding more product.
Both auralax.com (based in the United States) and primacoustic.com (based in Canada) offer starter studio or room acoustic starter kits. Going to their websites is an educational experience that truly explains that ‘There is no one-size-fits-all’ solution. The range of product types and uses and colors (including paintable product) is vast. They offer kits based on room size that can also be customized by adding your own preferences. It is a relatively simple way of getting up and running without spending a lot of money trying to figure out what works, and finding out what does not work–the expensive way.
If you are more the ‘do-it-yourself’ type, but would like some guidance they both offer consultation services. Just fill out the online forms to get professional recommendations. Auralax goes one step further by providing a free downloadable app for you to use. (There is a short tutorial on their website.) If you do not see the starter kit you like–just create your own.
If you do not have the money to spend on a full acoustic treatment, or you do not want to spend it until you are certain this is going to be a big part of your future, you can use materials that are usually readily available in you house. These include virtually anything with sound absorbing qualities such as blankets, a chesterfield, soft chairs, all those clothes your kids leave lying around. Old mattresses are great sound absorbers also. (I would stay away from the stained ones left by the curb. Just a thought.)
You can also make your own acoustic absorbers. This generally involves building a wood frame to hold rockwool like 2″ thick ProRox SL 960 Rockwool, then hanging them on the wall where you think they will do the most good. The rockwool will absorb sound waves, and if you pile the kid’s clothes on the floor in the corners as bass traps, your acoustics will certainly be better than those of a bare room. In all honesty, this looks like a waste of time, money, and effort to me.
Unless you have rockwool, wood, and some kind of screen material on hand ready to use–and the time, tools, and talent to put it all together, you are going to have to spend the money to buy supplies. ProRox SL 960 Rockwool is not exactly the cutest looking wall hanging and you should want to finish the wood. Combined with the fact that your time has to be worth something–this option just does not seem very appealing. Especially when compared to the cost of something like Studio Acoustic bass traps and enough Focusound 2″ Acoustic foam panels to treat 40% of a 12′ x 12′ x 8′ room. The cost of this professional quality solution should be under $500.00. And you can lay out the room and install everything in the time it takes to construct Roxul absorbers. Seems like a way better use of your time and money–to achieve a higher quality result.
Ceiling and Floor
Treatment of ceilings and floors, although not an afterthought, are something that can be dealt with as the studio grows and improves. Hardwood or laminate floors will not detract from the sound quality. (Note: Make sure you have a good quality underlay below the wood. Having a squeaky floor will not improve the recording.) If you in the garage with a concrete floor–and do not want the expense of putting down laminate–small area rugs where needed (under the drum kit?) should not affect sound quality.
Ceiling absorbers are certainly available but unless you are flush with cash, or have been doing this long enough that you are creating your second, or third, studio and know exactly what you want or need, you can wait for a long time before biting that bullet. Make good or great music first–then make it better.
Although most of the foregoing information is aimed at recording studio acoustics, much of it is also applicable to Home Theaters. If you have gone to the expense to get the 72″ flat screen with Surround Sound (or whatever it is called nowadays) and all of the other bells and whistles to have a superior viewing and listening experience, make sure you put some time, planning, and money into acoustics. Much of the product mentioned in this article comes in many styles and colors. Some of it is paintable (primacoustic.com) or fabric wrapped and can be integrated into your room décor. You do not have to be concerned about having charcoal grey bass traps stuck in the corners of your room.
On a Personal Note
Years ago I built a studio for my brother-in-law. At that time, my idea of better acoustics was ‘turn up the volume’. And as someone who lives with square, plumb, and level I was appalled at constructing angled walls and cutting apart and reinforcing trusses to give Becker a part of the ceiling that was 12′ high instead of 8′ c/w funky angled drywall and a skylight. (Of course, I also did not know why he collected different types of glass jars, weird metals, strange rocks, and other stuff he used to produce ‘music’.) The skylight opened to allow for ventilation. Hot air rises! And because sound generally travels in straight lines, it went straight up without disturbing the neighbors.
Although I love music, and usually have something playing while I write, I am no sound connoisseur. If Led Zeppelin IV is playing, people generally stay well away from the office. If it is the Moody Blues, my wife thinks I need a hug. But I certainly appreciate all of those who go to great effort to provide my musical enjoyment.
What all of that means is that I cannot help you with microphones, or motherboards (or skateboards for that matter). The only thing I know about ‘woofers’ and ‘tweeters’ is that one is usually a dog and one is usually a bird. Therefore, I have no intention of recommending, or suggesting, recording or studio products I know nothing about. And if I plagiarize someone else’s equipment suggestions, I would not even know if they are good or bad.