I am interested to know if any of you have any acoustical treatment in your studio.
If so, what have you got?
This following is an article that I wrote for "The Inner Ear Report", it appeared in Volume 15 #5. http://innerear.on.ca/backissues/vol15-5.html
It is a high-end audio magazine so I am writing to people with ungodly amounts of disposable cash. The average piece of gear reviewed would be $3,000 to $6,000 US. However the acoustical principles apply equally well to your home studio.
I am re-printing it here with permission for all my friends at PlanetZ:
Acoustics
So you’ve decided to buy a stereo system, a real one. You are committed to spending serious money in the hope of attaining audio nirvana. Money that could have been used to buy a car, (or to invest in some questionable venture that your cousin’s “friend” says is going to be big, really big), will be used to administer an act of self-indulgence.
Excellent!
No doubt you have budgeted for a compact disc player, a pre-amplifier, a power amplifier, speakers, and interconnects.
If necessary, you will have provided for speaker stands that will be massive enough to provide a suitable base for the bass. And of course it would be imprudent to invest this sort of money and fail to budget for a stand of equivalent quality for the other components.
It would also be foolish to simply plug all this wonderful stuff into the power company’s untamed power grid, so you better have some dough left over for a power conditioner that is up to the job.
If you are a regular reader of this fine publication then you no doubt have a number of pieces of gear that you cannot wait to go out and audition.
And therein lies the problem…
You will have to seek out the purveyors of this aural nectar and hear the various components at their various places of business. And by definition you will probably not be able to experience everything you desire all at one place.
Any serious audio retailer of merit will provide a comfortable and acoustically correct environment in which you can experience their version of ultimate sonic excellence. Unfortunately, unless you buy the exact system that you are listening to and then build the exact same room to put it in, you will never have that exact same audio experience ever again.
Why? Because there are two sides to every loudspeaker driver…
On one side of the driver you have a meticulously engineered enclosure which coddles the drivers by providing for their every need.
On the other side of the driver you have a room of some kind. This room is seldom meticulously engineered, and it is very likely that it possesses acoustic characteristics that have absolutely nothing to do with the driver’s concept of perfection.
Welcome to your room.
Your room has dimensions that will alter the sound of any system that you put in it. This is law of physics and is due to the phenomenon of standing waves. No matter where you place the speakers they will excite a room resonance, and this resonance will cause certain frequencies to be attenuated while others are over emphasized in very undesirable ways. In essence, you are not hearing the loudspeaker; you are hearing your room.
This raises two very important points.
Number one: you should expect to be able to audition equipment in your actual room before committing to a purchase.
Number two: you really cannot expect any loudspeaker to sound amazing in just any old room.
So many people have put so many hours into designing all this high tech gear and it is important to realize that you have taken on a responsibility; which is to provide a suitable environment to allow this equipment to function at it’s optimum.
Many articles have been written in many magazines (and even more on the web) purporting to disclose all of the secrets for rectifying your room’s acoustics. Many of these articles are actually full of relevant, useful facts. Just as many are full of half-truths, out-dated concepts and very questionable, (sometimes downright wrong) information regarding acoustical treatments.
This is not a simple problem. You cannot just move the speakers around and find a sweet spot. There isn’t one. You cannot just cover the walls and ceiling and floors in sound deadening materials. That will actually exacerbate the problem.
Equalizers will not solve your problems, and may actually damage things if used improperly. It is also incorrect to assume that non-parallel walls are the answer, they just make things more complicated. Realistically, unless you want to dedicate a substantial portion of your life to understanding the principles of acoustics, this is not a do it yourself proposition.
You spent a lot of money on your car. When your car is not functioning, do you fix it yourself? No, you hire professionals. So, if you spent a lot of money on your stereo system and you have acoustical problems with your room, hire a professional to fix it!
A real professional will assess your space and ascertain exactly what is wrong with your room. He or she will know all about standing waves and how to either absorb them or diffuse them. They should know about the balance between diffusion and absorption of problem frequencies. They should be able to solve these problems in an architecturally pleasing way
By the way, all of the above facts apply even more so to Home Theatre.
In addition to acoustic perfection, Home Theatre demands acoustic isolation (in my opinion so does listening to a piece of music at soul stirring volume!).
This is a much stickier wicket.
Unless you own your own home you probably cannot solve this problem legally, and you should refer to my article in the previous issue on headphones.
But let us assume that you are the proud owner of a chunk of real estate and talk about what it takes to stop sound.
Simply put: you can only stop low frequency sound with mass.
Egg cartons won’t do it, or carpet, or heavy drapes. All those things work on frequencies above about 500 Hertz, but the lower you go the harder it gets to stop the sound wave. Bass just keeps on going and going and going…
Low frequency sound contains a lot of energy. It will happily pass through most materials, and if not pass through them it will at least excite them into sympathetic resonance. Either way you will have unhappy relatives or neighbors when stuff starts exploding on screen at 110 deciBels at 1:00 AM.
Yes, there are materials out there that are specifically designed to address the problem of low frequency leakage. But you cannot buy them at your local hardware store, and besides that, if they are not installed correctly, it will be a waste of time and money anyway. Recording studios used to use lead sheets between the drywall layers, but these days a product like Acoustiblok (registered trademark) is usually used.
Call in the professionals. You will get what you pay for. Ask a lot of questions, and definitely ask to see (and preferably hear) the results of the company's previous work. At the very least ask to talk to previous clients to assure yourself that you are working with people who know that they are doing.
Here are some of the concepts that anyone you deal with should exhibit a thorough knowledge of.
Standing waves. These are caused by large parallel surfaces such as walls, ceilings and floors. When one of your room dimensions matches the length of a particular sound wave you will experience anomalies at that frequency (and all of the harmonics of that frequency) within the room. No amount of amplifier power applied to that frequency overcomes the problem, which is why equalizers will not work as a solution. It is important to understand that these problem frequencies are in the critical upper bass to lower midrange regions in an average sized room. As well, frequencies below 500 Hertz are difficult to absorb, and require technological expertise and the application of the correct materials to effect a remedy.
Flutter echoes. These are simply the high frequency cousins of standing waves. A quick test to see if you are experiencing this problem is to stand in the middle of the room and clap your hands or make the “ch” sound with your mouth. If you hear a quick series of little echoes, then you have a problem. Simply absorbing all the higher frequencies will eliminate the echoes, but it will also leave you with a dull, lifeless sounding room. This is where the concept of diffusion comes into play. Diffusion works by scattering the higher frequencies around the room in a more random pattern. It is most effective to use a combination of diffusion and absorption to deal with this portion of the audio spectrum.
Corner loading. This occurs when bass frequencies build up in the corners of your room, especially where two walls meet the floor. It causes peaks and dropouts in the critical bass region of your audio signal and causes no end of grief when you are trying to set up your speakers. There are a variety of acoustical treatment devices that can be used to alleviate this problem, such as Tube Traps (registered trademark), and corner bass traps.
If you cannot find a home audio acoustical consultant or home theatre installation expert in your area, you may try contacting the product manufacturers, such as Auralex or RPG directly to ask if they have a Dealer in your area.
Do it and you will discover just how great all that fabulous gear that you own actually sounds!
Copyright Rod Nattrass 2004