Sound Reduction Index Calculator
What is Sound Reduction Index Calculator?
A Sound Reduction Index (SRI) Calculator can be used to determine the sound insulation properties of a partition that separates two rooms or spaces. Based on the difference between the sound pressure levels in the source room and the receiving room, as well as the area of the test specimen and the equivalent area of the receiving room, it calculates the amount of sound reduction that a particular material or construction can provide.
Formula for Sound Reduction Index
The formula for calculating the Sound Reduction Index is:
R = L1 – L2 + 10 log10 (S/A)
Where:

R is the Sound Reduction Index in decibels (dB)

L1 is the average sound pressure level in the source room in dB

L2 is the average sound pressure level in the receiving room in dB

S is the area of the test specimen in square meters (m²)

A is the equivalent sound absorption area of the receiving room in square meters (m²)
Example Calculation of Sound Reduction Index
Suppose the average sound pressure level in the source room (L1) is 80 dB, while the average sound pressure level in the receiving room (L2) is 50 dB. The area of the test specimen (S) is 10 m², and the equivalent sound absorption area of the receiving room (A) is 8 m².
Using the formula above, the Sound Reduction Index (R) can be calculated as follows:
R = 80 dB – 50 dB + 10 log10 (10 m² / 8 m²) = 31 dB
Therefore, the Sound Reduction Index is 31 dB, which means that the material or construction provides a high level of sound insulation.
How to Calculate Sound Reduction Index
To calculate the Sound Reduction Index using the formula above, follow these steps:

Measure the average sound pressure level in the source room (L1) in decibels (dB) using a sound level meter.

Measure the average sound pressure level in the receiving room (L2) in decibels (dB) using a sound level meter.

Measure the area of the test specimen (S) in square meters (m²) using a tape measure or ruler.

Measure the equivalent sound absorption area of the receiving room (A) in square meters (m²) using a Sabine equation or a reverberation chamber.

Substitute the values of L1, L2, S, and A into the formula above and calculate the Sound Reduction Index (R) in decibels (dB).
FAQs
What is the Sound Reduction Index (SRI)?
The Sound Reduction Index (SRI) is a measure of the sound insulation properties of a particular material or construction.
How does the Sound Reduction Index (SRI) work?
The Sound Reduction Index (SRI) is calculated based on the difference between the sound pressure level in the source room and the receiving room, as well as the area of the test specimen and equivalent sound absorption area of the receiving room.
How can the Sound Reduction Index (SRI) be improved?
The Sound Reduction Index (SRI) can be improved by using materials with high sound insulation properties, increasing the thickness or density of the material, or reducing the amount of sound absorption in the receiving room.