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Uncorrelated SPL sum
Combine two independent sound pressure levels measured at the same receiving position.
First source level (dB SPL): -100–200; Second source level (dB SPL): -100–200
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Uncorrelated SPL sum
First source level (dB SPL): 90 Second source level (dB SPL): 90
- Combined level (dB SPL)
- 93.010300
- Increase above louder source (dB)
- 3.010300
L = 10 log₁₀(10^(L₁/10) + 10^(L₂/10)). Inputs −100 to 200 dB SPL, including fractions; 0 dB is a reference level, not absence of sound. Use the same receiver position, pressure reference, frequency band or weighting and averaging interval for both source-alone levels. This energy sum assumes zero correlation over that interval. Equal levels add 3.010300 dB; it is not an arithmetic average or a 6 dB coherent amplitude sum. Two loudspeakers playing the same signal may be correlated and require phase/frequency/geometry analysis. No propagation, room response, background subtraction, peak summation, exposure limit or compliance conclusion is calculated. Display uses six decimals without intermediate rounding.
Methodology
How it works
L = 10 log₁₀(10^(L₁/10) + 10^(L₂/10)). Inputs −100 to 200 dB SPL, including fractions; 0 dB is a reference level, not absence of sound. Use the same receiver position, pressure reference, frequency band or weighting and averaging interval for both source-alone levels. This energy sum assumes zero correlation over that interval. Equal levels add 3.010300 dB; it is not an arithmetic average or a 6 dB coherent amplitude sum. Two loudspeakers playing the same signal may be correlated and require phase/frequency/geometry analysis. No propagation, room response, background subtraction, peak summation, exposure limit or compliance conclusion is calculated. Display uses six decimals without intermediate rounding.
Method and assumptions documented by Techrider.live
2026-10-27
Frequently asked questions
Can I add measurements from different positions?
No. First determine each source-alone level at the same receiver with matching measurement settings. 90 and 88 dB give about 92.124426 dB. A source 10 dB lower adds about 0.413927 dB. The model does not correct incompatible measurements.