The acoustic environment you create during a building project matters, especially if you’re constructing an industrial facility with noisy machines and processes. One tool for simplifying your planning is to familiarize yourself with how sound interacts with your structure. In that spirit, here’s a brief overview of the sound absorption coefficient and its utility.
What Is It?
First, we must define the term. A sound absorption coefficient is the fraction of sound energy a material absorbs at one given frequency. Whatever it does not absorb and convert to heat (or motion) reflects off the material’s surface. Remember—one coefficient only applies at one frequency. As frequencies change, most materials’ coefficients rise, though some do fall. Also, every object, whether you use it to block noise or not, has some sound absorption coefficient.
This coefficient is a stable value between zero and one, one representing complete absorption at that frequency, while zero represents their complete reflection.
What Changes It?
Factors that affect absorption include:
- Wave frequency
- Angle of incidence
Porousness and thickness are properties of the absorbent material. Your coefficient goes up as porousness increases because these pores trap sound waves easier. Meanwhile, when you have a thicker and lighter substance to dampen sound waves, your coefficient also rises. You can test with many different frequencies while keeping the angle the sound waves uniform. To find an accurate coefficient, engineers average several different tests together for a final result.
Why Is It Useful?
Practically, those who design industrial facilities and commercial/residential properties benefit from sound absorption coefficients. As you weigh cost and sound absorption, this metric gives you another data point to assess their decision. If you want to soak up as much sound as possible, you’ll defer to something with a higher coefficient. But if absorption isn’t your highest priority, you can still keep it in mind as you consider other factors.
If you need assistive structures for blocking high-decibel noise, get in touch with our SVI Dynamics team regarding our industrial acoustic panels. We can give you a more in-depth overview of the sound absorption coefficient and how we design these for maximum absorption.