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Uncorrelated Sound Level Sum

Add two uncorrelated SPL contributions with compatible measurement conditions and distinguish the estimate from coherent signals and exposure.

Use this result well

Inputs that matter
Source 1 level (dB SPL), Source 2 level (dB SPL)
Output to expect
Combined sound pressure level
  • Check the units and required inputs before comparing results.
  • Keep the assumptions with a copied result so you can reproduce the calculation later.
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Reference & details

How it works

Two uncorrelated sound-pressure levels

Let M = max(L1,L2). Combined level = M + 10 log10(10^((L1−M)/10) + 10^((L2−M)/10)) An incoherent mean-square-pressure sum. Two loudspeakers carrying the same signal can interfere; phase and position matter. This does not sum digital peak meters or predict microphone/game mix peaks. An SPL estimate is not an exposure measurement or hearing-safety assessment.

Updated: September 2026

Example Scenarios

Add mean-square pressure for two uncorrelated sources measured at the same position with compatible weighting and time averaging.

Common Mistakes to Avoid

Applying two uncorrelated sound-pressure levels outside its stated assumptions

Two loudspeakers carrying the same signal can interfere; phase and position matter. This does not sum digital peak meters or predict microphone/game mix peaks. An SPL estimate is not an exposure measurement or hearing-safety assessment.

FAQ

Approximately 3.0103 dB for two uncorrelated equal mean-square contributions; coherent signals require phase information.

No. The readings need compatible measurement conventions.

About Uncorrelated Sound Level Sum

Add two uncorrelated SPL contributions with compatible measurement conditions and distinguish the estimate from coherent signals and exposure. Choose the mode that matches your measurements or study design, enter the stated units and keep the method and limits with the result.