Home Studio Acoustics 101. Section 2. Isolation.

ISOLATION

Isolation is a big need and frankly one of the hardest things to achieve in a home studio. Basically you want to keep all unwanted noise out. Recording an intimate vocal or acoustic guitar while the trash truck outside of your house beating the trashcans into submission isn’t so desirable in your recording. Dogs barking and old hill-billy East Texas trucks aren’t welcome either.

Mass is a key to isolation. The more dense your construction materials the better because sound is more impervious to dense materials. This has to do with the molecular structure of the materials themselves. Not going there.

If you have the opportunity to have separate mix and recording rooms do it. This “isolates” the element being recorded from other noise producing elements such as computers, monitor speakers, engineers, etc. Typically these separate spaces are divided by a wall or two and sometimes include a double, non-parallel paned window for visual communication. Here is a pic of a studio I was blessed to help build the acoustics for in Lubbock. This is an example of the one of the isolated recording spaces.

In my case, I have not had the luxury of having 2 permanent separate rooms setup for recording purposes. Right now I rock a single room that I use for both recording and mixing. When in the same space as the musician, I monitor the recordings with headphones and try my best not to move and create chair and floor noises. I do use some home-made tube traps (more on this later) to create a “wall” around the instrument or vocal to help with isolation. Moveable walls called “Gobos” are easy to construct and can incorporate sound absorbing materials and diffusion as well.

If possible the desired construction of a space suitable for recording consists with the concept of double-wall construction. Essentially, a room within a room. This is actually 2 walls, doors, or window panes is with a small space between them. The purpose of this is that when one is hit with the sound and then travels through, the vibrations from the first wall are not passed on to the next because they are not touching. Also, this air space helps dissipate the passed sound by reflecting back and forth within the gap. In some cases the walls are purposefully not parallel to reduce resonance. Expensive noise isolating double-wall construction, doors and windows are not really an option in most home studio budgets. Commercial studios actually spend millions on construction dollars into creative ways to reduce potential problems from unwanted noise.

Most of the places I’ve used for recording have in been temporary and rented facilities. For me, it’s all about what I can to do to minimize the small things that are within my control. The outside door to my studio and windows both rattle at lower frequencies if not tamed with some inexpensive weather stripping from Lowes or Home Depot to fill these gaps. The doors in my space have weather stripping to help seal the room as much as possible too.

Another equally annoying noise is the heating and air conditioning units and the air they push through vents. Many suggest over adequate air handlers that super cool or heat the studio air with quick bursts. These units are placed at a distance for the recording space to help eliminate the mechanical noises associated with them. My favorite and obviously less expensive alternative is the handy “OFF” option on our HVAC system. When we are recording, I set it to OFF and when we are breaking or listening I move it back to the on position. Ask any small/home studio engineer and they’ll agree this is very common.

Distance from the source of the noise is great too and make off the road, out of the city studios desirable. The best way for me to avoid outside nuisances is to plan recording sessions during quite times. In the strip mall space we had for Studio Java/Dixon Productions a few years ago, this was in the evenings typically after 7. Then and on weekends. Fortunately, this is also some of the best hours for musicians. In my space now (our house) this is great time as well except for the noises that permeate from the adjacent rooms, my girls. I do my best to plan sessions when they can leave for a few hours or over night. Seems to never fail though that when I do plan sessions time at off-peak hours, turn off the HVAC system, etc… dogs that I’ve never heard before in my life seem to have barking competitions and birds outside our windows chirp with excessive joy.

Isolation is a beast to conquer correctly in a home studio environment. For me it’s all about the small things I can do such as weather stripping and planning sessions at quieter times of the day. Many times ABSORPTION is a great solution to help minimize “leakage”. Thick curtains is a great example of reducing and therefor helping isolate the outside world.

ABSORPTION will be covered in section 3.