Sound Reduction Index Calculator

Formula

The formula to calculate the Sound Reduction Index (R) is:

\[ R = L1 - L2 + 10 \log\left(\frac{S}{A}\right) \]

Where:

\(R\) is the Sound Reduction Index (dB)
\(L1\) is the average sound pressure level in the source room (dB)
\(L2\) is the average sound pressure level in the receiving room (dB)
\(S\) is the area of the test specimen (m²)
\(A\) is the equivalent sound absorption area of the receiving room (m²)

What is a Sound Reduction Index?

A sound reduction index is a metric used to measure the level of sound insulation a structure provides.

Example Calculations

Example 1:

Average Sound Pressure Level in Source Room (L1): 80 dB
Average Sound Pressure Level in Receiving Room (L2): 50 dB
Area of Test Specimen (S): 10 m²
Equivalent Sound Absorption Area (A): 5 m²

Using the formula:

\[ R = 80 - 50 + 10 \log\left(\frac{10}{5}\right) = 80 - 50 + 10 \log(2) \approx 33.01 \text{ dB} \]

Example 2:

Average Sound Pressure Level in Source Room (L1): 90 dB
Average Sound Pressure Level in Receiving Room (L2): 60 dB
Area of Test Specimen (S): 20 m²
Equivalent Sound Absorption Area (A): 10 m²

Using the formula:

\[ R = 90 - 60 + 10 \log\left(\frac{20}{10}\right) = 90 - 60 + 10 \log(2) \approx 33.01 \text{ dB} \]

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