Enter the intensity of the absorbed sound and the intensity of the reflected sound into the calculator to determine the Sound Absorption Coefficient. This calculator can also evaluate any of the variables given the others are known.

Sound Absorption Coefficient Formula

The following formula is used to calculate the Sound Absorption Coefficient. 

SAC = Ia / (Ia + Ir)

Variables:

  • SAC is the Sound Absorption Coefficient (unitless, between 0 and 1)
  • Ia is the intensity of the absorbed sound (W/m²)
  • Ir is the intensity of the reflected sound (W/m²)

To calculate the Sound Absorption Coefficient, divide the intensity of the absorbed sound by the sum of the intensities of the absorbed and reflected sounds. This will give a value between 0 and 1, where 0 indicates perfect reflection (no absorption) and 1 indicates perfect absorption (no reflection).

What is a Sound Absorption Coefficient?

A Sound Absorption Coefficient is a measure that quantifies the extent to which a material, surface, or object absorbs sound waves, thereby reducing the amount of sound reflected back into the environment. It is expressed as a value between 0 and 1, where 0 indicates perfect reflection (no absorption) and 1 indicates perfect absorption (no reflection). This coefficient is frequency-dependent, meaning different materials absorb different frequencies of sound to varying degrees.

How to Calculate Sound Absorption Coefficient?

The following steps outline how to calculate the Sound Absorption Coefficient (SAC).

  1. First, determine the intensity of the absorbed sound (Ia) in W/m².
  2. Next, determine the intensity of the reflected sound (Ir) in W/m².
  3. Next, gather the formula from above: SAC = Ia / (Ia + Ir).
  4. Finally, calculate the Sound Absorption Coefficient (SAC).
  5. After inserting the values of Ia and Ir into the formula and calculating the result, check your answer with the calculator above.

Example Problem:

Use the following variables as an example problem to test your knowledge.

Intensity of the absorbed sound (Ia) = 10 W/m²

Intensity of the reflected sound (Ir) = 5 W/m²