Improving sound quality and architectural acoustics can positively impact employee productivity in office settings and increase the living quality of residential structures. Thus, acoustical design is no longer a luxury afforded to high-end projects. It is a necessity that has far-reaching effects on projects of all sizes and types.
Acoustic control should be considered early in the project planning and design process. The desired acoustics for a space will dictate which building materials should be used, and where. Specifically, when designing for a project that requires a quieter, more sound-absorbent atmosphere, acoustic insulation will play a crucial role.
Read on to learn more about common architectural acoustic challenges architects must overcome, followed by 7 strategic ways to use insulation for sound control.

Common Challenges in Architectural Acoustics

Sound is the movement of energy. It is created when objects vibrate, affecting and vibrating the air around them to produce the audible noises the human ear eventually receives. When it comes to architectural acoustics, knowing how to direct or abate this movement of energy to align with the purpose of a space is a critical task.

Complicating the matter, features of a room affect how sound vibrations travel throughout the space and affect the people using it. Because there are so many variables that can affect how sound travels in a space, there are numerous factors to take into consideration—and attempt to address—when designing for a project.

Open Concept Spaces

Open concept spaces can foster team collaboration and unity. Unfortunately, these open spaces offer nothing to block or absorb airborne noise. Thus, the commotion from employees talking, phones ringing, and hallway traffic can make for a disruptive environment if not managed properly.

Environmental Noise

It is important not to underestimate the effect of environmental noise on the acoustics of a building. Things such as vehicle and pedestrian traffic, and other sounds from the exterior of the building, also can impact the level of noise and the quality of acoustics in a building.

Poor Room Adjacencies

When planning for sound-control insulation, it is important to consider the sound profile of adjoining rooms. Consider, for example, a conference room placed next to a break room. One would need to ensure utmost privacy for the conference room and take additional steps to prevent outside noise from being transmitted into the room.

Mechanical Equipment Placement

Mechanical equipment such as HVAC units are essential for the overall comfort of the office environment. Unfortunately, often these units can transmit noise throughout the building. Equipment location, mounting, and duct insertion loss all should be considered when analyzing the selected system.

7 Ways to Use Acoustic Insulation to Enhance Architectural Acoustics

Using sound-blocking or absorptive insulation is just one of many techniques to improve acoustics in a building. Additional techniques include masking the sound and isolating the sound. Many of these techniques are effective as individual solutions, but for best results, consider using more than one of the following
suggestions.

1. Control Noise in Wall Partitions

Wall partitions separate spaces within a building. The most common way to enhance noise control in wall partitions is to add mass and insulation. The additional mass and insulation add resistance for the sound waves to pass through. Options to increase mass include adding layers of gypsum board to the assembly. Along with adding mass, it is important to fill the wall cavity with a sound-absorptive insulation, such as fiber glass or mineral wool. To reduce the maximum amount of sound transmission, both mass and insulation are required. Isolation of the partition components through the use of resilient channels and furring also is effective at reducing “acoustic shorts.” Proper perimeter wall sealing and door gasketing must accompany any sound transmission class (STC)-rated assembly to ensure performance.

2. Use Sound-absorptive Insulation for Suspended Ceiling Systems

Sound improvements can be made in ceiling systems by adding ceiling panels made of composite materials, usually composed of mineral fiber or glass fiber. The noise reduction coefficient (NRC) performance ratings for cast mineral fiber panels range from
0.65 to 0.95. The NRC ratings for dry-felted glass fiber panels range from 0.95 to 1.0.

3. Reduce Sound Transmission with Sound Batt Insulation

Sound can bend and flow around objects, or “leak” through tiny spaces. Hand-stuffed fiber glass and foam insulation (and sealants, where applicable) can greatly reduce unwanted sound transmission through these voids. Filling empty cavities also can help to improve the STC rating.

4. Absorb Reflected Sounds with Acoustic Insulation

Walls, ceilings, floors, and furnishings can reflect airborne sound like voices and music. They can also transmit impact sounds, such as footsteps on a floor. The unwanted reverberation of sound occurs when the airborne vibrations strike an acoustically reflective surface of another medium—like a wall, ceiling, or floor—that bounces the sound back into the room.

Using acoustic insulation with high NRC values helps absorb sound, as opposed to reflecting it back into the room. A portion of the absorbed sound is converted into heat, and a portion of it is absorbed into the insulation.

5. Install Acoustic Insulation Boards

An easy, less invasive technique for controlling sound is the application of acoustic panels in the finished space. The panels consist of fiber glass or other sound-absorbing material covered by fabric. The panels are attached to the walls or ceilings, or hung, to help control sound. In general, the more square feet of absorptive material exposed in the space, the better reduction of the reverberated noise.

An example is a gym with hard surfaces. Hard surfaces cause reverberation even after the source of the sound has ceased. Too much reverberation results in echo. Adding panels in a gym can help prevent reverberation from occurring by diffusing the sound.

6. Reduce HVAC Noise with Acoustical Board

Noise pollution occurs from a variety of places, but a common cause is HVAC systems. Whether it is duct transmission noise (insertion loss) or the mechanical equipment itself, the sound and resulting vibration can disrupt office and home environments. Ductwork and open plenums are often undesirable “speaking tubes” from space to space.

Designing and installing acoustical wall and ceiling liners and acoustical boards is one of the most effective ways to reduce noise in buildings with exposed structure finished spaces and in plenums. It can be detailed so as to not detract from the architectural design and can be integrated in most conditions. It is also one of the least-expensive solutions. Plumbing can be another source of noise, and insulation to reduce its noise should also be considered.

7. Use Concave or Convex Insulation to Enhance Acoustics

The shape of a room and its corresponding insulation can greatly affect the way sound moves. Concave shapes tend to bring sound to one focal point, while convex shapes diffuse sound in multiple directions. Depending on the needs of a particular space, these shapes may or may not be beneficial.

Final Thoughts

Using acoustic insulation can greatly improve the sound quality in a building. Insulation combined with isolation and sound-masking techniques can minimize unwanted noise and make for a more enjoyable and productive environment.

This article was written by several contributors from the Knauf Technical Support and Product Management Group. Many companies make acoustical insulation, but for information on Knauf’s products or design solutions, visit www.knaufinsulation.com.