Studio Construction & Sound Treatment

As featured in: Performing Songwriter, May 2004.  Visit performingsongwriter.com to order back issues or subscribe.

By Daniel Keller

Outside of a handful of highly trained individuals, the science of what makes a room sound a certain way is looked upon as a sort of black art. In the more well-heeled musical circles, in everything from large-scale performance venues to upscale tracking and mixdown rooms, considerable sums are routinely spent in the name of sonic treatment.

But for the average musician, budget for acoustic treatment has traditionally ranked well below the more tangible fun stuff like instruments, toys, recording gear, toys, effects boxes, toys and more toys. Even if you’re fortunate enough to be at liberty to physically alter your musical space, budgeting for two-by-fours, shectrock and caulking doesn’t tend to hold the same appeal as that new synth or 12-string you’ve been pining for.

Fortunately, the same technological revolution that has brought digital multi-tracking into spare bedrooms and one-car garages has also created low-cost solutions for many of the common acoustical issues facing the average musician. In this article we’ll examine some of the technologies and products currently available to smooth out your sonic nightmares.

SCRATCHING THE SURFACES

Let’s start off with a disclaimer: The purpose of this article is not to give you an education on acoustics. There are plenty of authoritative books and articles on the subject, among them F. Alton Everest’s classic How to Build a Small Budget Recording Studio From Scratch, as well as great articles including Fett’s earlier in-depth study in the December 2000 issue of this very magazine. Rather, our goal is to talk about some of the most common issues we encounter in our musical spaces and some of the means available to address them.

That said, let’s divide the concept of acoustic treatment into some basic categories. There’s insulation, which usually entails keeping the sounds of the outside world out, or keeping your own sounds in. Closely related is isolation-the art of keeping individual sounds from bleeding too heavily into each other.

The other problems we face are a bit more subtle and have to do with how our rooms affect the sounds we’re creating in them. In any given space, the characteristics of that space have a direct effect on what we’re hearing. That’s why an instrument will sound different in a large hall than it will in a small club. It’s also the reason your mix sounds different in your home studio than it does when you’re squirm-ing in your chair in that A&R guy’s office.

The average home studio or rehearsal space rarely does well in addressing any of these issues. Most times we’re dealing with a spare bedroom, converted garage, basement or loft, none of which boast construction aspects that are in any way conducive to good sound. Thin, parallel walls, box-shaped rooms, low ceilings and rattling window frames are only some of the enemies we face.

Even a few short years ago, the only way to address these issues involved massive amounts of money, materials and frustration. While the ultimate solution is still to plan and construct a purpose-built environment from the ground up, these days there are a number of ways to markedly improve your odds of making your workspace sound better without having to sell your instruments or smash your fingers.

SOUNDPROOFING AND INSULATION

One of the most frustrating aspects of sound is that it will go where it wants to and find its way through any space via any available path. That’s why it’s so important (and so difficult) to block any potential points where sound can leak through. In all cases, mass is your friend-the thicker and denser your walls are, the better they’ll be at stopping sound.

Even more effective is mass combined with air. The most common construction technique is what’s known as a “floating room,” where an entirely new set of walls, floor and ceiling are built within the exist-ing space, detached and separated by sev-eral inches from the outside walls. If you’re constructing your own space, companies like Acoustic Systems, Soundproof Windows and AllNoiseControl offer a line of soundproofed doors and windows, while Troy Sound Wall Systems and AllNoiseControl also offer soundproof wall panels in pre-set or custom sizes.

Even if you don’t have the luxury of new construction, sealing areas of potential leakage in your existing structure will go a long way toward keeping the inside sounds in and outside out. For doors and window frames, look for the thickest, densest weather stripping that will fit in the allotted space. Use caulking to seal around areas like heating and air conditioning ducts, electrical outlet boxes, lighting fixtures, unfinished drywall joints and, if you’ve got them, tiled ceilings. While there are countless varieties of commercially available caulks and sealants, consider a latex sealant designed for acoustical applications, like SoundSeal from Acoustical Solutions.

You can also accomplish a lot by adding sound-blocking layers to your existing walls. Several companies offer low-vibration materials that are exceptionally dense but surprisingly thin and lightweight. This material can be purchased by the roll from companies like Auralex Acoustics, Acoustical Solutions, Acoustic Sciences Corporation (ASC), Netwell Noise Control and Acoustics First, to name a few.

IF YOU CAN’T DO THE WHOLE ROOM

For many of us, especially those who can eschew live drums, the toil and expense of insulating the entire room can be avoided by simply isolating only those elements that need it. In larger studios, isolation booths have long been used to separate the vocalist or drummer during a live take. While these tend to be of the permanently constructed variety; a number of companies offer portable, lightweight “iso-booths” that can be assembled quickly and easily when and where you need them.

WhisperRoom, Acoustical Solutions, VocalBooth, ClearSonic and Acoustic Systems all offer various sizes of portable iso-booths, or you can search the web and find plans to build your own.

Another variation on the iso-booth that has become increasingly popular is the aplifier chamber.  These can vary from small soundproofed boxes just large enough to hold your guitar amp and a mic stand, to cabinets with speaker and mic (XLR) jack built in, like the Randall Isolation Guitar Cabinet.

YOUR BIGGEST FAN

As computers have become increasingly ubiquitous in the studio, so has the need to hide the annoying whirr of their fans. If your room is otherwise relatively quiet, the background hum of one or more computers can adorn your delicate acoustic tracks with all the ambience of a runway at Heathrow.

If you’re reasonably computer-savvy (or know someone who is), replacing your computer’s stock fan with silent offerings from companies like Enermax, Antec or Mad Dog Multimedia is a quick way to reduce the noise. These companies, as well as many others, also offer sound-dampening cases and quiet cooling systems that can knock off several decibels of noise.

Companies like Sound Construction and Supply, Noren Products, Vantec and Cooler Master also offer cabinets to completely enclose your computer’s CPU. And check out sites like CompuQuiet.com, Silentmaxx.net and QuietPCusa.com for tips, tricks and products to tame the beast.

SEMI ISOLATION

In many cases, complete isolation is neither necessary nor desirable. As anyone who has ever recorded a live band will tell you, a little leakage can be a good thing, adding a natural-sounding clement that’s sometimes lost by separating things too much. In many cases, a bit of baffling between players and/or amps is all that’s necessary to provide enough separation for a decent recording.

This is typically accomplished with a gobo, a small portable wall panel around four or five feet tall. Many people build their own, sometimes covering one side with carpet or other absorptive material, the other with a reflective surface like parquet, and putting them on wheels for easy maneuvering. You can also check out pre-manufactured versions like the Stack-It modular system from Taytrix, as well as ClearSonic’s transparent acrylic panels.

FIXING THE VIBE

Let’s shift gears now and talk about the other major challenge in any studio: controlling the sonic characteristics of your space. Every acoustic environment’s sound is 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.

For the vast majority of us, the spaces available for our creative environments typically end up being smallish boxes with parallel walls that tend to encourage the buildup of standing waves, resonant frequencies and other sonic anomalies that can substan-tially color what we’re hearing, rarely for the better. The hard surface of a side or rear wall can create reflections that can significantly change the sound of your mix.

FIRST, IDENTIFY THE PROBLEM

Today, many software programs offer tools to help identify some of the most common issues. Spectral analyzers, also known as Real Time Analyzers (RTAs), are basically meters that break the sound down by var-ious frequency groups, and can tell you a lot about what your room is (or isn’t) doing to your mix. By using a reasonably sensitive microphone at various spots throughout the room, an RTA can help identify areas where there’s an excess buildup of certain frequencies. Some audio software applications, like Steinberg’s Wavelab, have RTAs built into them. You can also get dedicated software, such as Smaart from SIA Software or Spectro-Foo from Metric Halo, TrueRTA from True Audio, Room Optimizer from RPG Diffusor Systems, or hardware units from a multitude of companies including Tektronix, Phonic, Behringer and many others.

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.

STOP AND REFLECT

Generally your 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, greatly lessening their impact.

Much can be accomplished using common sense and everyday materials. The rear wall of one project room I work in has a large floor-to-ceiling bookshelf, fully stocked. Heavy carpeting and thick theater-style curtains also work well, and you’d be surprised at the differ-ence a strategically placed, overstuffed sofa can make.

But a number of commercial (and slightly less unwieldy) products are also available. For absorption, look to acoustic foams and fiberglass panels and blankets from companies like Auralex, ASC, RPG, lllBruck-Sonex, Media Specialty Resources (MSR), Acoustical Solutions, ClearSonic, Netwell Noise Control, Noren Products, Taytrix, Middle Atlantic Products and a host of others.

These companies (and others) offer a number of diffuser products as well. Auralex and RPG, for example, are widely known for their geometrically shaped panels and materials. Attached to your flat surfaces at strategic locations, these can go a long way toward breaking up and eliminating reflections. And a number of these companies, including MSR, offer products created of dense, uneven mate-rials that will both absorb and diffuse sound waves.

Bass traps are another popular means of addressing specific areas of your environment. Their often cylindrical shape and uneven, absorptive finish work wonders to break up reflections in problem areas of your room. I’ve seen people construct these from plastic trash cans, though less inelegant versions are available from companies like ASC, RealTraps and Auralex. Many companies offer bass traps that also perform as speaker stands or studio furniture, such as the Double Duty models from Acoustics First or the Mobilio products from ASC.

Many companies offer entire modular environments. Some examples include ASC’s popular Tube Traps, Studio Traps and Attack Wall; Auralex’s MAX-Wall line; MSR’s SoundPanel system and RPG’s Studio in a Box.

CONCLUSION

The science of acoustics can be wide-ranging and confusing. While we know a lot about how sound behaves and what to expect from a given space, there are always enough variables to keep it interesting. A new instrument, more bodies in the room-even changes in the weather-can influence the way things sound. What works for one situation may not be ideal for another, and the best we can do is try to 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 instru-ments 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.