A topic that comes up frequently in discussions of home recording is "Room Treatment". It's a difficult topic in many cases, as people are understandably reluctant to make major changes to their home environments. Spouses may object to the idea of hanging sound panels on walls, and renters may be entirely prohibited. Adding room treatment can be invasive, cost money, and potentially be a lot of work. And there's always the question: "Will it actually make any difference?". It's clearly a lot more fun to buy a new mic, or a new recording plugin, or even a new guitar! Just hanging panels on the walls isn't very exciting. Or is it?
There is a lot of information on the web about sound treatment (just do a google search...), so I'm not going to try to do a complex topic justice here, but let's cover just a few basics and then most importantly, I'll demonstrate the effect of room treatment in my home studio.
- What's the Problem? Sound is highly affected by its environment. We all know how singing in the shower sounds different than singing, say outside. The shower has lots of hard surfaces, which causes echos and reverb as the sound reflects off the wall. Outdoors, you have little to no reflections, so everything sounds dry. Instruments like guitars actually need some reflections from a room to sound their best, but a room that is too reflective can color the sound in a negative way, even if you don't hear obvious reverb. Rooms, like instruments, have resonant frequencies that can affect how music sounds. To some extent, our ears compensate for these effects. But microphones don't. Recording in a room with untamed resonances, reflections or even audible reverb will generally sound distant or indistinct. The guitar may sound harsh, or some notes may sound boomy. Think of how a small flashlight looks in bright daylight vs how it looks in a pitch dark room. Sound is similar - your guitar can be "lost", sounding small and distant in a room with poor room acoustics, but sound present, full, and direct in a room with "good" acoustics.
- What's the Solution? Basically, we need to add things that absorb and break up the sound, so we don't get resonances and reflections. if you want to be very correct about it, it may possible to identify specific problems and deal with them, like specific frequencies that are problematic. But in reality what most people do is just apply broadband absorption. There are commercially available panels that can be hung on walls or placed in corners. Some of the companies like ATS or GIK offer calculators to help you figure out what you need and sell room kits to get you started. Or you can build your own (as I did) using absorbing materials. Owen Corning 703 fiberglass is sort of the standard, but there are other materials that can work as well, including Rockwool (which may be easier to get at local home improvement stores) and "acoustic cotton", which is a somewhat nicer material to work with than fiberglass. Again, do a search on "acoustic treatment" if you want to do a deep dive and really understand both the problem and the solutions.
- What About Acoustic Foam? There are companies that sell foam-based products that claim to treat your space. In general, these are not adequate. Foam absorbs high frequencies. It looks pretty, and can make a space sound "dead", but for recording, the problems are often with lower frequencies, and foam is simply not effective there. Good acoustic treatment needs to be more substantial and uses materials that are more absorbent at all frequencies.
- Can't I Just Avoid This? Maybe... maybe not. It depends in part on your tolerance - how important is making a good recording to you? What's the goal of the recording? If you're just recording yourself as part of practicing, then you may not care. If you are sharing music with a few friends, you also may not care. But for wider distribution, you may want your music to sound "professional". It also depends on your specific space. Some rooms may "accidentally" sound OK. In some cases, a reasonably furnished room may be relatively acceptable, especially combined with "close micing" - placing the mics within anywhere from a few inches to a foot from your guitar. I'll explore this idea more in another blog post in the future!
- So, How Much Difference Can it Make? This is best answered with a demo, so have a listen to the audio in the video below. I compare three recordings of the same guitar, same short noodle, in three different situations. 1) The first recording was done in my garage prior to being acoustically treated as I was converting it to a home studio. I recorded with 1 mic, a Neumann TLM 103, placed 18 inches from a guitar (a Ryan Mission Grand Concert). 2) Then, after quite a lot of work, and a lot of OC 703 in the ceiling and corners, and some commercial panels (Real Traps), I recorded again, in the same location, same mic distance. You should hear some obvious reduction in echo, tho still far from ideal. 3) The third and final recording was done after I was completely finished. In the final phase, I added 8 more homemade panels, added some rugs to the floor, added a bit of furniture, and finally recorded in a more realistic way, using a pair of mics (Neumann KM184s) in stereo, moved up to 8 inches from the guitar. By the way, counting all the panels, corners and ceiling coverage, I probably have the equivalent of about 30 2x4ft panels in the final room. Your results may not be this dramatic, and you probably won't need as much treatment, since I started with a rather worst case, hard walls, concrete floor and so on!
As always, YMMV, but this is what I experienced.