When acoustics come into play, most people think of concert halls and recording studios. But good acoustics are important for any room or building and can make a huge difference in how well you hear everything.
Many products are available to help control sound in buildings. These include acoustic foam, which comes in a range of styles that integrate aesthetically into interior surfaces.
Sound Absorption
When sound waves hit a surface, some of that energy passes through and is absorbed by the material. Other energy is reflected, and some of it is converted to heat energy. The ability of a building material to absorb or reflect sound depends on its density, thickness, and surface texture. Soft, pliable materials absorb and transmit more sound than rigid or impenetrable ones, while surfaces that are rough or have high friction tend to reflect more.
The ideal materials for absorbing sound are soft and light in weight. These characteristics make foam a great choice for absorption. It also has the added benefit of being environmentally friendly and free from volatile organic compounds (VOCs).
Many spaces with a lot of hard parallel surfaces experience problems with excessive reverberation. When speech isn’t intelligible due to reverberation, it can lead to a noisy, distracting environment that reduces productivity and causes stress for occupants. Absorption products reduce reverberation by preventing the echoes from reflecting back off the walls and ceilings.
To effectively add acoustic absorption, a wall or ceiling must be made with a high acoustic rating. These ratings are typically measured with an NRC or Sabins value. NRC values measure the acoustic performance of a surface while Sabins ratings are based on an individual panel’s performance. While both methods can be used to indicate how much acoustic absorption is in a space, they are not interchangeable. NRC values describe the acoustic performance of large surface areas such as an acoustic ceiling or carpet on the floor while Sabins ratings are specific to a single acoustic panel.
Sound Insulation
Sound insulation is designed to prevent the transmission of sounds between rooms. It also helps to prevent the reflection of sounds off surfaces inside a building, reducing echoes. It is especially useful in homes where multiple people live together or where loud activities take place.
Many materials have good insulating properties, such as foam, fiberglass and rock wool. Some have the additional ability to absorb noise, as well. A material’s acoustic properties are largely determined by its mass and density. The more dense a material is, the harder it is to vibrate, making it better for absorbing sound.
The acoustic performance of materials depends on the thickness and mass per area, as well as their structural integrity. It’s important to balance acoustic efficiency with other factors, such as dynamic stiffness and load-bearing capacity.
For example, thick fabrics like theater curtains and studio blankets are good at absorbing sound, but they don’t have as much of an insulating effect as more rigid materials. This is because a thicker material has less surface area than a thinner one.
There are a number of products that can help with acoustic insulation, including acoustic caulk and soundproofing spray foam. Many of these products are designed to improve airborne sound insulation between the party walls or timber joists in houses and flats. They can help to meet (and in some cases exceed) Part E of the Building Regulations for sound proofing.
Acoustic Blankets
While not the best choice for soundproofing, acoustic blankets can help with a variety of temporary noise mitigation needs. They are thick, heavy fabrics that reduce echo and reverb that happens when sound reflects off bare walls. They are great for recording studios and theaters because they allow you to create a more acoustically dead space, which leads to high quality audio recordings.
They also work well for blocking noise from equipment like chillers and refrigeration units, fans/blowers, compressor housings and hydraulic pumps. Commonly referred to as noise barriers, they are custom fit to encapsulate noisy equipment and have an STC (sound transmission class) rating that indicates their ability to block directional noise.
Acoustic blankets come in a variety of sizes and materials, including moving blankets that are used to wrap furniture during a move or studio blankets made from recycled consumer fibers. They typically have a low NRC (noise reduction coefficient) and provide broad acoustic treatment coverage at a relatively low price per square foot.
They can be hung from the ceiling or on walls and are easily customizable to meet specific noise control needs. They can include grommets for hanging and can be cut to size, slit or patched to accommodate windows and doors. They can also be sealed around equipment to create an enclosure or a fence on a construction site to meet local noise ordinances.
Acoustical Foam
Acoustic foam is a type of sound treatment that improves acoustics in spaces by reducing sound reflections and noise. It’s commonly used in recording studios, home theaters, offices, and other spaces where the quality of sound is critical.
Open-cell acoustic foam absorbs airbone sound waves, reducing their amplitude and dissipating them as heat energy. This reduces the reverberation time, improving speech intelligibility and sound clarity. It can be made from polyurethane or melamine foam and is available in different sizes, shapes and colors.
Wedge-shaped acoustic foam has great acoustic properties, offering excellent absorption of mid and high frequencies. Pyramid-shaped acoustic panels, which feature four sides instead of two, offer a bit more diffusion but still excellent performance. Eggcrate foam offers a more cost-conscious option that is effective at suppressing reverberations but doesn’t fully deaden the room. Thicker acoustic foam, often in metal or wood enclosures, can be used as bass traps to minimize reverberations of lower frequencies.
Other acoustic treatments can be applied to walls and ceilings to further reduce unwanted reverberation, such as rock wool panels or QuietFibre, which is made from mineral or stone wool. These acoustic insulation products are designed to fit snugly between wall studs and are often covered with an acoustical breathable fabric for a sleek finish. They’re also useful for dampening reverberations and improving the sound of home appliances, electronic devices and alarm systems. They do not, however, block sounds from passing through the walls or other structures of a building. To do this, additional soundproofing measures must be employed, such as soundproof barriers, caulking, insulation and double glazing.