By Greg Cahill
Whether you’re trying to minimize the impact of the scratchy sound of a novice violinist or the annoyingly repetitive exercises employed while refining your legato technique, a quiet rehearsal space is a godsend for a player seeking solace and housemates who want to binge-watch Netflix in relative peace. After all, a stringed instrument is an acoustic machine designed and set up to produce not only beautiful tone, but volume that can project to the back of a concert hall. Sure, you could use a mute, but that will alter the tone—at least occasionally you want to hear yourself playing at full throttle in order to master performance-level technique.
Here are five things to consider that can help you create a quieter rehearsal space and bring peace of mind to family and friends (not to mention any aggrieved neighbors).
1. Set a budget
Soundproofing materials can be expensive. It’s best not to use cheap or fly-by-night materials—like egg cartons or Styrofoam peanuts—that can be ineffective, messy, or even a fire hazard. There are a number of excellent online companies—including Acoustical Solutions and AudiMute—that sell commercial-grade materials at reasonable prices. And their customer service departments will help find the best solution for your needs. But be realistic about how much you want to spend before starting the project.
2. Temper your expectations
Professional sound designers warn that it is next to impossible to completely isolate sound in a room, since sound waves can be absorbed by the ceiling, the walls, and the floor and are readily transported through building materials to the outdoors. This impact can be mitigated by insulating the walls sufficiently with fiberglass, foam, or cotton insulation, and placing a thick sheet-rubber barrier between the wallboard and the room’s wood framing. But this can be a relatively costly procedure and, unless you’re starting with an unfinished room (like a garage), it’s unlikely that you’ll want to strip your existing practice room down to the studs to add these foundational soundproofing materials. But there are other options, like laminated soundboard. Also, remember, if air can move in and out of your practice room, so can sound. You will want to place rubber or foam insulation—weather-stripping will do the trick—in any door or window crack to keep the sound inside.
3. Sometimes less is enough
You don’t need to eliminate all of the sound to get results. Reducing the sound emitted from a room by just 10 decibels (dBs) will create the perception of a 50 percent reduction on the part of an outside listener. A 20-dB reduction of the sound level will bring the perceived sound level down by 75 percent. By comparison, normal conversation ranges from 60–65 dB and traffic noise from inside a car is about 85 dB. Download a free or inexpensive decibel-meter app onto your smart phone and ask a friend or family member to measure the sound level while standing six feet away from the practice space, with the door closed, while you play. Be sure to play at the loudest volume you will use during rehearsal. The resulting decibel reading will give you a baseline upon which to gauge the success of your efforts. The typical sound level of a violin is about 70–90 dB (a cello can range up to 110 dB).
4. Not all sound is created equal
High frequencies and midrange tones produced by a violin or viola have unique signatures characterized by short sound waves. A cello, and especially a double bass, can produce bass waves that are much wider—so wide, in fact, that a bass wave can pass through a cinder block before it is fully formed, making it necessary to “trap” the bass wave inside the room so it can be tamped down before it moves outside. You will want to buy soundproofing that will treat the frequencies produced by your specific stringed instrument—for example, a violinist or violist will not need a bass trap placed in the corners of the room to inhibit bass waves, whereas a cellist or double bassist may want to utilize this option.
5. What are the best options?
The goal is to create an acoustically “dry” room that doesn’t produce a lot of reverberation and that enables you to hear your instrument without ambient effects. To achieve this goal, you want to minimize the amount of reflective surfaces that allow sound waves to bounce around. So, for example, if you have a hardwood floor, you should lay down a carpet or some type of sound-absorbing material. Here are five of the most popular soundproofing treatments. Familiarize yourself with the noise reduction coefficient rating (NRC) to determine the sound-absorption quality—a higher NRC rating indicates maximum effectiveness:
Soundboard: These large panels resemble sheets of drywall, but are a laminate composed of several layers of acoustic-grade plasterboard, mass-loaded vinyl, closed-cell foam, and more mass-loaded vinyl. The sandwiched panels can be cut to size and screwed in place over your existing drywall to create an effective sound barrier. You can use these on the ceiling as well. Requires some construction skills.
Latex wall liners: This is a new technology that uses rolls of latex that can be attached to the walls or ceiling. The science behind this development is simple: A sound wave hits the center of the latex-covered area and travels to the edge and then back to the center cancelling the next sound wave along the way.
Acoustic foam: These lightweight panels, constructed of rows of wedge shapes that can reduce echoes, are available in a variety of sizes and colors. They are highly effective at absorbing the high- and mid-range frequencies produced by violins and violas. You can experiment with the results by adding as many panels as needed.
Acoustic panels: Often made of foam, mineral wool, or fiberglass enclosed in decorative fabric, these panels can be interspersed along a wall or ceiling to absorb sound waves and reduce reflection. The advantage is that you don’t need to completely cover a wall to get the benefit. (These are often used in restaurants to cut the din of loud conversation.)
Acoustic blankets: These are similar in appearance to large moving blankets, but are constructed of acoustic-grade insulation sewn into fire-retardant fabric. They’re effective at absorbing sound and relatively easy to install—you can nail 1×2-inch boards along the top of a wall and attach the blankets with heavy plastic clips. I have used these over a combination of drywall, a rubber barrier, and fiberglass insulation to soundproof a garage after one of my neighbors called the police to complain about my son’s punk band. Sound levels were reduced significantly from 110 dB at the property line ten yards away to 50 dB. Haven’t heard from my neighbor since.
This article originally appeared in the May 2018 issue of Strings magazine.