06 Oct Sound Treating Our Portland, Oregon Studio
This week began the exciting task of sound treating two of the rooms in our new music recording studio, dubbed Laetoli Music Recording Studio, home to Demo My Song. “Sound treating” a space, often confused with “sound-proofing,” is a very important way to gain more control of the acoustics in your room, usually through the use of sound absorbing panels and diffusers.
Most rooms are naturally prone, due to their shapes and sizes, to various acoustical anomalies. One such problem in mixing situations is a phenomenon known as “one note bass” in which there is one particular note in the bass register that sounds significantly louder than the others. For example, a bassist could be playing a C major scale and then suddenly, the G note sounds twice as loud as the others. This is due to the sound waves being produced actually bouncing off the walls and combining in an additive fashion to create a perceived increase in volume at that pitch/frequency. Most rooms are prone to this problem and the exact frequency (i.e. note/register) at which it occurs varies based on their size and shape.
A common solution for this problem, and one that we have employed in our new studio, is low frequency and wideband absorbers. Low frequency absorbing panels may also be referred to as “bass traps.” We began with the mixing room. Luckily we had already assembled all of the panels themselves as they were initially built and installed in our previous studio in Langley, Washington.
Frequencies in the bass range tend to “build up” in the corners of the room so it is common to attempt to “kill” your corners with sound absorbing material. Pictures below show both home made versions of such panels as well as ones purchased specifically for that purpose.
We also built and installed a pair of “helmholtz resonators” in the “Orange Room” which are designed to absorb low frequencies while deflecting higher ones. They are finished with untreated Western Red Cedar 1×4’s which gives the “Orange Room” a distinctly sweet aroma reminiscent of a sauna.
The next thing we installed was high frequency foam panels (begrudgingly purchased from Guitar Center.) I find it’s easy to make the mistake of using “too many” of these types of panels rendering your space so devoid of reflective wall space that it sounds unnaturally “flat” or “dry.” The extreme example of this effect would be an anechoic chamber, which is so “dry” (i.e. without any natural reflection) that people often describe the experience of walking into one as “nauseating.” This is because our equilibrium relies partially on the ability to interpret our surroundings from sound reflecting back to us (just like bats and their ability to navigate), so it’s easy to be thrown off balance when suddenly, we perceive no reflection of sound at all!
In order to have some flexibility in how much high frequency absorptive material was being used at any given time we developed a simple system for mounting the foam that lends itself well to various applications. The system involves stringing two strands of bailing wire (used for it’s affordability) in parallel between a pair of brass hooks (see pics below). With this system panels can be added or taken out as needed and need not be glued directly to the wall which is great!… because you can use them again and again. This technique also worked great on the ceiling at our old studio.
The only panels we have yet to install in the “Orange Room” are the pair of semi-cylindrical poly diffusers. These two units were also built while at our previous studio space and the design came directly out of How to build a small budget recording studio from scratch…with 12 tested designs written by Mike Shea and F. Alton Everest, which is a great resource for those building their own recording studio. We will mount them soon but haven’t yet decided where they will be best placed.
Another great idea we picked up from the aforementioned book involves the use of garden trays. They are built from standard square gardening trays (the ones with the perforated bottoms, widely available for free at places like Walmart and Home-Depot) and are filled with two layers of ¾ inch Owens Corning 705 rigid fiberglass insulation. Between the gardening tray’s perforated bottom and the panels of 705 is a layer of fabric which serves not only to keep the irritating fibers concealed, but also give you an opportunity to get creative with various designs and patterns. When completed the panels are fixed directly to the wall or ceiling with 4 small screws. Below is a pic of the panels we installed in the “Red Room.”
Lastly, we installed a cord “run” so that it was easy to share mic and computer cords between the Red and Orange Room. This was built of a 6 inch section of 4 inch diameter ABS black plastic pipe. We were surprised to find when we cut into the wall that, rather than cutting into a traditional wall cavity, we actually cut into an old doorway which had been “walled” over at some point in the past. We cut the hole in the wall first with a drill with a 1 inch diameter, then completed the hole with a jig-saw. After inserting the pipe we caulked the edges on both sides… voila!
Stay tuned for more exciting updates on our studio building progress.