As musicians, most of us have a love-hate relationship with acoustics. In the concert hall, architectural acoustics are carefully employed to create unique-sounding spaces where a well-tuned combination of reverberance, warmth and clarity can transform and enliven the music we make. But when we’re at home, acoustics can seem more foe than friend. We worry about bothering our families or neighbors or about getting just one recording without exterior noise, especially if we live in dense, urban areas. These sound struggles have spun a number of acoustics myths, driving us to line our walls with egg cartons or mattress pads – solutions the internet may think are great but in reality are ineffective or even dangerous. Fortunately, there are real-world solutions to controlling sound that don’t involve creative recycling.
Noise 101: How Sound Gets from One Room to Another
First, let’s break down the three main types of noise problems. While many of us may be familiar with room acoustics terms like “absorption” or “reflection,” these terms mostly apply to how sound works within rooms rather than between them. For the latter, musicians should know that there are three main ways in which sound passes between rooms: flanking, transmission loss (or airborne noise) and structure-borne noise.
Flanking involves sound leakage through a hole in a barrier, such as through doors and windows, ductwork or improperly sealed openings between walls and floors. The unfortunate news about flanking problems is that they can’t be truly fixed without structural changes, such as adding insulation, sealing joints or rerouting ductwork. The only action a lowly renter like yours truly can take against flanking is perhaps closing a door or a window, so we’ll be moving on to the other two types of noise problems.
Transmission loss describes airborne sound transmission between rooms or from the outside. Sound travels through the air to a surface, such as a wall, where it radiates through that surface to the other side. This is the type of sound leakage most of us are familiar with: think listening to traffic from inside your home.
Structure-borne noise occurs when sound is transmitted through vibrations that travel through walls or floors, causing them to vibrate sympathetically.
Here’s an easy experiment that can help us better understand transmission loss and structure-borne noise. Find a room, a partner and some kind of sound source such as a phone or small speaker. Have your partner stand outside the room playing music while you go inside. Shut the door. If you can hear the music inside the room, that’s airborne noise (transmission loss). Now, have your partner place the speaker against the wall. In most cases, the music will become significantly louder to you. When the speaker is placed against the wall, it transfers its energy directly through the structure, which vibrates like a membrane, radiating sound into the adjacent room – hence the term “structure-borne noise.”
Now let’s tackle some myths about sound and acoustic treatments. We’ve all probably witnessed makeshift home studios clad in mattress pads, egg cartons or blankets. These methods, though cheaper than buying legitimate acoustical treatments, are ultimately ineffective: they rely on the myth that covering a room in sound-absorbing or scattering treatment is the most effective way to prevent noise from getting in or out of the room. At their worst, they make your home more susceptible to fire.
The Mattress Pad Myth: Mattress pads are usually intended to mimic professional foam bass traps, which are wall-mounted acoustic treatments used to attenuate low frequencies. Even though they may look or feel similar, they don’t work the same way. Bass traps aren’t primarily used for noise isolation – they’re used to prevent pesky room modes and excess reverberation that hinder critical listening and recording. Besides, hanging acoustic treatment is used primarily for reducing reverberation within a room. While it has some effect on noise transmission between rooms by attenuating the strong reflections that can cause excessive loudness (think playing in a bathroom), it has no effect on wall-based, structure-borne noise or flanking.
The Egg Carton Myth: Similar to the mattress pad myth, this myth tries to use egg cartons to scatter or diffuse sound. Again, this method is ineffectual compared to professional wall diffusors, and, again, it isn’t used for noise isolation – it’s used to break up unpleasant reflections in rooms with parallel walls.
The Blanket Myth: Like foam mattress pads, covering a room in blankets doesn’t really prevent sound from escaping. However, hanging thick drapery like velvet around windows can block a little bit of exterior noise.
Above all, never treat your walls with anything that isn’t flame retardant. Remember that most mattress pads, blankets and egg cartons are flammable. Be safe and use professional acoustic treatment or curtains that are fire-resistant.
Real Noise Solutions
Fortunately, there are real, strategic solutions for minimizing sound leakage. First, it’s worth mentioning that some noise-related conflicts can be solved by talking to neighbors, having regular and consistent practice times and avoiding playing early in the morning or late at night.
But if you must practice at these times, consider the most effective solution for noise control: quieting the source. That means using a practice mute if you’re a string or brass player, a weighted keyboard (with headphones) if you’re a pianist, or a practice pad if you’re a percussionist.
Then, try to find the most acoustically private space in your home. To do this, determine which walls you share with neighbors. This usually means finding the most interior room in your building. The more walls that are between you and your neighbors, the harder it will be for airborne noise to make it into their space. If this room has a window, you can hang drapery to help prevent the intrusion of environmental noise. Always make sure the door is shut when you practice. If you live in a studio apartment, practice in the middle of the room with your instrument facing an exterior wall. If your room is comprised of hard surfaces and prone to excess reverberation, consider purchasing some fiberglass panels to attenuate reflections that can make rooms louder.
You can also decrease structure-borne noise. If your instrument is stationary, like a piano, drum set or vibraphone, avoid placing the instrument against a wall. Regardless of what kind of floor you have, consider putting anti-vibration pads typically used for appliances under the legs of your instrument. If you play the cello or any other instrument that connects to the floor, use a rubber rock stop. Whatever your instrument, it’s a good idea to practice on top of a rug or, even better, a squishy rubber mat in order to “decouple” your feet or chair from the floor, preventing the transmission of sound through floor vibrations. If your instrument is downward facing, like the clarinet, the mat should be large enough for it to absorb the sound from your instrument as well. If your instrument requires an amplifier or speaker, make sure it is placed on an absorptive surface, like a mat or carpet.
For a savvy musician, practicing at home doesn’t have to be a battle. By harnessing the clever tricks of room acoustics, making music can be a little more harmonious for all of us.