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:
- The automotive industry, which often uses foam to insulate engine compartments and interior cabins.
- Machinery and industrial noise control, where loud, ongoing noises are a safety hazard for workers.
- Generator enclosures and air compressors, allowing technicians to maintain high power output without fear of crossing sound pollution thresholds.
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.
