Music & Acoustics

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Combining Two Sound Levels

Total level when two sound sources play together.

Formula

L = 10 \log_{10}(10^{L_1/10} + 10^{L_2/10})

Variables

LCombined level (dB)

L_1Level 1 (dB)

L_2Level 2 (dB)

Example

Two 60 dB sources: L = 10 log(2×10⁶) ≈ 63 dB

Did You Know?

Two identical sounds add only 3 dB, not double — doubling loudness needs ten sources, not two.

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