How Effective Is Soundproof Insulation?

Soundproof insulation can be a powerful resource for reducing sound, but the term "soundproof" may not mean exactly what you think. When evaluating how effective an acoustic solution is, you'll need to know what to expect from soundproofing and whether sound mitigation or sound control products might make more sense for you.

Sound is complex and travels in many ways, so you'll need the right kind of sound-mitigating solution to remove unwanted sound from your space. We'll go over the basics of sound-reducing technologies and which ones work in different scenarios. A sound engineer may be necessary for specific situations.

Understanding Sound With Different Types of Insulation

Several types of insulation can help diminish sound, but the best one for the job depends on what type of sound you need to reduce. Different materials are more effective on different sound frequencies. You may need a product that addresses the right frequency range for your application. If you're just getting started researching materials for sound insulation, then sound transmission class (STC) ratings can  be great starting point in assessing the effectiveness of a material. 

STC ratings use a single number to reflect how effective a construction assembly is in blocking sound from passing through it. They apply to both individual materials and entire assemblies, like walls, floors, ceilings, and partitions, depending on the material. Generally, a higher numbers indicate more sound-mitigating materials. 

Below are the STC ratings showing the audibility of loud speech from the opposite side of a wall:

• 25: Easily understood
• 30: Fairly understood
• 35: Audible but not intelligible
• 45: Must strain to hear
• 48: Barely audible
• 50: Inaudible

Many regulations and codes require or suggest specific minimum STC ratings. These requirements typically come from the ASTM International standard, ASTM E-90.

Remember that STC ratings address airborne sound, which moves through the air. It does not measure impact sound, which moves through structures, such as the sound of footsteps that carry through the floor of an apartment. The impact insulation class (IIC) offers a similar measurement for this type of noise. Additionally, for more specific frequency performance, be sure to review the per frequency rating chart found on the data sheet for the material you are assessing.

The type of sound is another key element in the efficacy of your solution. Using insulation to reduce noise can work through one of several principles:

• Absorption: Materials can absorb sound waves and prevent them from bouncing around a space, creating echo and reverberation. Sound-absorbing materials reduce noise generated inside a room, such as echo in an office space or recording studio.
• Isolation: Isolation keeps noise from transferring through a barrier, such as a floor or wall. Usually, when someone talks about soundproofing, they're referring to isolation. It works on unwanted sounds both entering and leaving a space. It can keep an office quiet amid loud outdoor noises as well as loud duct work, or help prevent band practice from bothering the rest of the household.
• Diffusion: Diffusion refers to spreading a sound evenly throughout a space and can help improve sound quality. For example, a concert hall might use diffusion to control sound reflections off of walls and deliver it evenly to the guests.

You can usually use insulation for sound isolation and absorption. Diffusion requires another acoustical system.

Insulation for Soundproofing

Insulation for reducing noise can come in several styles and materials. Each one affects unwanted sounds differently.

Spray and Injection Foam Insulation

One option you might find is spray or injection foam insulation. These products absorbs sound primarily by filling in gaps, preventing sound from moving through them. They can help as part of a larger soundproofing plan and offer other benefits, but they won't provide nearly as much noise reduction as some other solutions.

Fiberglass

Fiberglass is a common and effective material in insulation and has the added bonus of having some soundproofing capabilities. Well know for its sound absorption qualities, fiberglass weaves glass pieces in with plastic fibers to create a budget-friendly acoustic absorber. It can dampen airborne and impact sounds significantly. Thick, dense fiberglass generally absorbs more unwanted sound than thinner materials.

Mass-Loaded Vinyl Barriers

Mass-loaded vinyl (MLV) is a low-profile material that blocks sound waves. It's the preferred choice for reducing sound transmission between rooms. MLV barriers are a cost-effective first step in reducing noise. They work well in commercial and residential applications, like multifamily housing, offices, and home theaters. Builders often use this material as a layer within walls. You can also wrap it around noisy mechanical components, such as ducts and pipes.

For these applications, look for MLV that can resist corrosion, heat, rot, and other environmental effects. You can also combine MLV barriers with other materials, like a layer of fiberglass batt. The vinyl blocks sound, while fiberglass absorbs it. MLV barriers are one of the most effective options for soundproofing.

SPI subsidiary brand, GLT, fabricates Vinaflex™, a high quality MLV product, in Cleveland, Ohio as well as multiple shipping locations across the country. Our VinaFlex™¿ VN Noise Barriers offer STC ratings between 21 and 34. Rigorous testing shows which frequencies each product is most effective at reducing. You can choose the best fit for your project. For instance, VN-150 becomes more effective at higher frequencies, reducing a 4,000-Hertz (Hz) sound by 44 decibels (dB). Conversely, VN-200 only reduces sound by 41 dB at 4,000 Hz, but it offers more effective noise reduction across the lower frequencies. 

These values come from rigorous testing to ASTM E-90-97 E413-87. While real-world results can vary from lab testing, third-party testing supports accuracy and compliance.

Other Considerations for Soundproofing

Remember, soundproofing is often complex and frequently accompanies construction and design. While determining which type of insulation is best for your project, keep these factors in mind:

• Installation requirements: Ensure your soundproofing insulation fits its environment. For example, MLV can resist mold and condensation.
• Fire codes and regulations: Commercial and residential insulation must meet specific fire ratings. Look for ASTM-rated supplies, like foil-faced VinaFlex™¿ FF-100, a Class-A fire-rated product tested to ASTM E-84.
• Complementary materials: Consider the purpose of the space in your project. Could additional materials help with soundproofing? Thick curtains, rugs, and pillows could help dampen sound in a home but might be less appropriate for an office space. Also, landscaping installations such as trees and shrubs can help prevent exterior noise from entering a building.

Soundproof With SPI

Soundproofing and other noise reduction techniques must address different frequencies, installations, and environments. Specialty Products and Insulation (SPI) carries the powerful VinaFlex™¿ brand in several styles. These options include MLV reinforced with foil or adhered to fiberglass decouplers.

SPI has extensive experience in the insulation field. Our seasoned team members can help you find the right soundproofing insulation for your projects. When you work with SPI, you get a partner who prioritizes responsiveness, integrity, and support. If you're unsure what noise-reducing insulation is best for you or need more information, contact a sound insulation expert today.