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Decibel Calculator

Decibel Calculation Formulas: Sum, Subtract, and Average

Understanding how to sum, subtract, and average decibels is essential in acoustic engineering and noise measurement. Each operation has its own formula, as outlined below:

How to Sum Decibels

The formula for summing decibel levels (Lp) is:

Lp=10log10(10Lpi10)

How to Subtract Decibels

The formula for subtracting decibel levels (Lp) is:

Lp=10log10(10Lpi10(10Lpi10))

How to Calculate the Average Decibel Level

The formula for averaging decibel levels (for example, on a surface, following ISO 3744) is:

Lp=10log10(1N10Lpi10)

Important Remarks

Note: It is not possible to mix different operations (sum, subtract, and average) within the same calculation.

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