Open Cell Foam vs. Closed Cell Foam

The material you select for sound insulation projects will significantly impact the level of sound absorption and attenuation you can expect to achieve. Open cell and closed cell foams are two effective material options for such applications, each with its own unique structure, benefits, and uses. Read on to discover how open cell and closed cell foams are both alike and distinct from each other to help decide which option is the right choice to address your acoustic needs.

Open Cell Foam vs. Closed Cell Foam Structure and Composition

Recognizable for its porous structure, open cell foam is constructed from an interconnected cell network that facilitates airflow for heightened breathability and air permeability. Its open cells also make the material more flexible. In contrast, the cells found in closed cell foam are sealed off, meaning that air and water can’t pass through them. Closed cell foam has a higher density, making the foam material quite rigid while offering enhanced capabilities for sound absorption and attenuation.

Performance of Open Cell Foam vs. Closed Cell Foam

While each foam type is advantageous in its own way, the following is an overview of open cell and closed cell foam performance:

  • Durability. Closed cell foam holds up better than open cell varieties, giving it good application versatility and the durability to handle insulation projects.
  • Moisture resistance. Closed cell foam offers better resistance to moisture thanks to its impermeable structure. Open cell foam has a higher chance of developing mold because it runs the risk of absorbing and holding moisture.
  • Thermal insulation. Open cell foam’s breathable, porous structure lends it to applications within controlled indoor environments. Conversely, closed cell foam is an optimal choice for outdoor applications and settings that will expose it to moisture due to its higher R-value.
  • Sound absorption. Open cell foam exhibits superior sound absorption capabilities due to facilitating airflow within its cell network. Besides having a lower density, this material is softer and thicker, minimizing sound waves with greater efficiency than closed cell foam.

Closed Cell Foam Applications

Between its sound insulative qualities and its ability to resist water, closed cell foam is ideal for applications like the following:

  • Air security
  • Ceilings
  • Gasketing
  • Insulation
  • Mats
  • Neoprene products
  • Reinforcement for construction materials

Open Cell Foam Applications

Open cell foam is compatible with the above applications, as well. However, open cell foam achieves better air permeability, giving it additional applications in acoustic absorption and sound attenuation.

Acoustic Absorption

Two material options for open cell foam in acoustic absorption applications are polyether and polyester. Polyether foam is crafted from open cell polyurethane. Flexible and lightweight, this compressible foam offers impressive sound absorption as well as thermal insulation capabilities. Alternatively, polyester foam exhibits superior tensile strength.

Sound Attenuation

To reduce noise and noise pollution or dampen its transmission, open cell foam is a good choice for:

Cost Considerations

Compared to closed cell foam, open cell foam is significantly less expensive as it requires less plastic material to manufacture. This translates to lower costs while providing the same degree of thermal insulation through the effectiveness of its air permeability as an insulator. Although open cell foams are more cost-effective per cubic foot, closed cell alternatives are more successful at maintaining their performance capabilities over time. Just be aware that for installing closed cell foam, you may need specialized equipment.

Acoustic Absorbing Foam and More From Technicon Acoustics

To choose between open cell and closed cell foam, evaluate the specific needs and environment of your application. Open cell foam offers good sound absorption and attenuation as well as air permeability at a more economical price. Closed cell foam is durable and water-resistant for outdoor environments.

As a leading manufacturer of innovative products for acoustic and thermal applications, Technicon Acoustics, Inc. has been supplying OEMs throughout North America with custom solutions for over 40 years. Our team understands the key elements to designing sound enclosures and related goods, so we offer acoustic absorbers and barriers, vibration damping products, and an array of films, facings, and adhesives to meet the versatile needs of clients in industries ranging from air compressors and power generation to medical devices and specialty vehicles.

Offering a lead time of two weeks and a quality control rating of 99.91%, we strive to create the Perfect Order Experience for our customers. Contact us for help deciding between open cell and closed cell foam, or request a quote today on one of our many product options.


How Does Foam Absorb Sound?

Sound is simply vibration, moving through a medium such as air, that we can perceive with our sense of hearing. Those vibrations or waves are cycles of compression and rarefaction, rhythmically displacing the molecules of the medium between the sound source and the listener. These cycles, or frequencies, are louder or quieter depending on how much energy, or amplitude, the sound source inputs into the medium.

Sound pollution comes from many sources including heavy trucks and equipment, construction and industrial machinery, power generation operations, and more. It contributes to an uncomfortable or unpleasant work environment and can also reduce workers’ ability to communicate with each other or to hear equipment or vehicles, posing serious safety risks. One solution is to absorb unwanted sound vibrations with foam materials. Keep reading to learn more about how foams can be used to absorb sound.

How Does Foam Absorb Sound?

It’s important to understand that foam does not block sound; however, it can absorb it to varying degrees. Sound absorption improves acoustic quality in a space by reducing the sound you hear and by controlling echo and reverberation.

As sound waves interact with objects in their path, the object absorbs certain frequencies and reflects others, based on its material properties. The degree to which sound is absorbed at different frequencies is called the material’s sound absorption coefficient. It measures the ratio of absorbed sound energy versus that which is reflected. It is expressed with a value between 1 for total absorption and 0 for no absorption at all.

There are two primary mechanisms for how foam absorbs sound:

  • Energy conversion, where vibratory energy is converted to heat.
  • Trapped sound waves, where air pockets in the foam contain the sound, stopping it from reflecting into the environment.

The Role of Acoustic Foam’s Material Properties

Foam has different cell structures, which affect its permeability and airflow. There are two types of cell structures in acoustic foam: open cell and closed cell. Both feature a sponge-like, interconnected structural network, but as its name implies, open cells are open on all sides, while closed cells include at least some membranes that keep the cells sealed and separated. Open cells are more permeable, giving them a higher sound absorption coefficient.

Density and Thickness

The thickness and density of a foam material also affect sound absorption, particularly frequency response. Thicker, denser foam increases its acoustic impedance, which is a material’s opposition to sound waves of a particular frequency or frequency band. Thus, it’s important to match sound-absorbing foam to the offending frequencies.

Applications of Sound Absorbing Foam

Sound-absorbing foam has numerous real-world applications. In an industrial setting, excess noise and vibration can increase stress and interfere with communication, resulting in preventable safety risks. The mechanical vibrations can also disrupt sensitive electronics and other scientific instruments.

For these reasons and more, sound-absorbing foam is an effective solution for applications as broad as:

Sound Absorbing Foam from Technicon Acoustics

Technicon Acoustics continues to refine the science and application of sound absorption for a variety of industrial settings. Specially engineered foam is an effective solution for excess sound reverberation, improving comfort, safety, and equipment function.

We supply foam and other acoustic absorption products that work with a wide range of frequency spectra, and with varying degrees of absorbability. Contact us to learn more about our sound-absorbing foam products, or request a quote for help selecting a product for your application.