Time & Space - Studio Acoustics for Home Audio Recording
Now You Have Time, Let's Talk About Your Space.
As more and more of us are required to stay home, many people are taking the time to rediscover their home studios. That often also means rediscovering the sonic challenges of those spaces.
Whether it’s complaints from the neighbors, that one bass frequency that makes the walls shudder in sympathy, or an annoying slapback, we know how frustrating it can be to have your creative flow disrupted by bad room acoustics.
With thin walls, boxy shaped rooms, low ceilings, rattling window frames and more, the average home studio or rehearsal space rarely does well in addressing these issues. And these are only some of the difficulties we face.
Fortunately, the same technological revolution that brought multitracking into basements and garages has also created low-cost high-quality solutions for many of the common acoustical issues facing the average home studio. Here, we’ll look at a few ideas to smooth out any sonic concerns.
We’re going to divide the concept of acoustic treatment into two basic categories:
- Soundproofing and insulation
- Reflection and diffusion
Soundproofing and Insulation
In short, insulation helps keep the sounds of the outside world out and vice-versa. Closely related is isolation which manages individual sounds from bleeding too heavily into each other. So, the first issue to tackle is soundproofing and insulation to block any potential points where sound can leak through. There are several solutions, but first things first: mass is your friend – the thicker and more dense the walls are, the better they’ll be at stopping sound.
Significantly more effective is mass combined with air. Perhaps you’ve heard of a “floating room”? This is where an entirely new set of walls, floor and ceiling are built within the existing space, detached and separated by several inches from the outside walls (and, in the case of flooring, by rubberized “floaters” that lessen the transfer of vibrations). Basically a room within a room! If so inclined, there are companies that offer soundproofed doors and windows, as well as soundproofed wall panels in pre-set or custom sizes.
Sealing areas of potential leakage in the existing structure is also exceptionally helpful in soundproofing and insulation. For doors and window frames, use the thickest, most dense weatherstripping that will fit in the allotted space. For areas surrounding heating and air conditioning ducts, electrical outlet boxes, lighting fixtures, unfinished drywall joints and tiled ceilings, use a latex sealant designed specifically for acoustical applications.
A lot more may be accomplished by adding sound blocking layers to the existing walls. Several companies offer low-vibration materials which are exceptionally dense but surprisingly thin and lightweight.
If You Can’t Do the Whole Room…
The amount of labor and expense required to insulate an entire room can be daunting… but it can also be avoided simply by isolating only those elements that need it. A number of companies offer different sizes of portable, lightweight “iso-booths” that can be assembled quickly and easily. Alternatively, a quick search on the web yields a multitude of DIY plans.
Another variation on the iso-booth that has become increasingly popular is the amplifier chamber. These can vary from small, soundproofed boxes just large enough to hold an amp and a mic up to cabinets with speaker and input jack built in.
Reflection and Diffusion – Identify the Problem
Reflection and diffusion have to do with how the room affects the sounds we’re creating in them. In any given space, the characteristics of that environment have a direct effect on what we’re hearing. That’s why an instrument will sound one way in an empty cathedral and completely different in a tiny club. It’s also the reason why listening back to mixes in various locations sounds so different.
This is a major challenge in any studio – controlling the sonic characteristics of the space. These are dictated by a number of factors, including the distance between walls, the height of the ceiling, the angles at which the walls meet and the materials comprising the surfaces, not to mention the composition and placement of tables, pictures and other surfaces, furniture, curtains, etc.
Unfortunately, home studios typically tend to encourage the buildup of standing waves, resonant frequencies and other sonic anomalies that can substantially color what we’re hearing, rarely for the better. The hard surface of a wall or ceiling, for example, can create reflections that significantly change the sound of a mix.
Before discussing solutions, though, let’s identify the problem areas first.
Many of today’s software programs and apps offer tools to help identify some of the most common issues. Spectral analyzers – aka Real Time Audio meters (RTAs) – are meters that break the sound down by various frequencies. By using a reasonably sensitive microphone in various spots throughout the room, an RTA can help to identify areas where there’s an excess buildup of certain frequencies.
One important caveat here: meters can be invaluable when used correctly, but meters don’t mix music – your ears do. Trust your ears first and foremost. Listen and compare, then use the meters to verify what you’re hearing.
Reflection and Diffusion – Design the Solution
Generally, the best defense against unwanted reflections is to attack problem areas with a combination of absorption and diffusion. Absorptive materials prevent or greatly reduce reflection, while diffusers break up the reflection, scattering the waves in a multitude of different directions and greatly lessening their impact.
Much can be accomplished using common sense and everyday materials. For example, one wall could rely on heavy carpeting or thick, theater-style curtains. Another could house a large, fully stocked floor-to-ceiling bookshelf. A number of products are available for purchase, including acoustic foams, fiberglass panels and blankets.
Also available for purchase are diffuser panels. These panels come with geometrically-shaped attachments that are then placed on the walls. Position these in certain, strategic locations to help break up and eliminate reflections. Additionally, many companies offer products created of dense, uneven materials that will both absorb and diffuse sound waves, resulting in the best of both worlds.
Bass traps are another popular means of addressing specific areas of the environment. These uneven cylinders contain an absorptive finish that works wonders towards breaking up reflections in problem areas. Many companies offer bass traps that also perform as speaker stands, studio furniture, and even entire modular environments.
Additional Problems and Solutions
Having covered the main concepts of acoustic treatment, here’s a couple more important things to think about.
If you’re into rock ‘n roll, noisy fans are a welcome part of the scene. If you’re trying to create music in your home studio, though, noise is undesirable and annoying. Did you know that computers can be one of the biggest contributors of noise to the studio space? If you’re reasonably computer-savvy – or know someone who is – replacing the computer’s stock fan with a whisper-silent one is a quick way to reduce the noise. Another option is to look into sound-dampening cases with quiet cooling systems, which can knock off several decibels of noise, as well as cabinets that will completely enclose the computer’s CPU.
In many cases, complete isolation is neither necessary nor desirable. A little leakage (aka bleed) can be a good thing; it adds a natural-sounding element that’s sometimes lost by separating things completely. A bit of baffling between players and/or amps may be all that’s necessary to provide enough separation for a decent recording.
The best solution for semi-isolation is a gobo. A gobo is a small, portable isolation panel that absorbs and/or diffuses sound. Homemade ones are typically covered with carpet or other absorbent material on one side and a reflective surface, like parquet, on the other. Pre-manufactured versions are available for purchase.
The science of acoustics can be wide-ranging and confusing. While we know a lot about how sound behaves and what to expect out of a given space, there are always enough variables to keep it interesting. A new instrument, additional bodies in the room, even changes in the weather… everything can influence the way things sound. What works for one situation may not be ideal for another and the best we can do is to try and create as neutral and objective a listening environment as possible. Arm yourself with good monitors, meters and spectral analyzers, identify and correct obvious problem areas, and listen to as many different types of music, mixes and instruments as you can. But at the end of the day the most important tools you have are your ears – if it sounds good, it probably is good!