Sound Reduction Index Calculator


Calculating the sound reduction index (SRI) is crucial for understanding the effectiveness of materials in reducing noise transmission. This article presents a simple calculator to determine SRI, along with explanations and examples.

How to Use

Enter the necessary parameters into the calculator fields and click the “Calculate” button to obtain the SRI value.


The formula for calculating the sound reduction index is:


  • α is the sound absorption coefficient of the material.
  • σ is the surface density of the material.

Example Solve

Suppose we have a material with a sound absorption coefficient α=0.3 and a surface density σ=5. Plugging these values into the formula:




So, the sound reduction index (SRI) is approximately -5.228.


Q: What are the units of the sound reduction index (SRI)?

A: The SRI is a dimensionless quantity, typically expressed in decibels (dB).

Q: How accurate is this calculator?

A: This calculator provides accurate results based on the input parameters. However, variations may occur depending on specific environmental factors.

Q: Can the SRI value be negative?

A: Yes, negative SRI values are possible, indicating a reduction in sound intensity.


The sound reduction index calculator presented here offers a convenient way to determine the effectiveness of materials in reducing noise transmission. By inputting the relevant parameters, users can quickly obtain SRI values for various materials.

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