Soma dois SPL iguais
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
About this calculator
The 'Add Two Equal SPL' calculator helps determine the total sound pressure level (SPL) when combining two identical sound sources. SPL is a logarithmic measure in decibels (dB), and adding two identical sources doesn't follow linear addition but increases by 3 dB. This occurs because sound pressure is a quadratic quantity, and the total sound energy doubles. The formula used is SPL_total = SPL_individual + 3 dB.
This tool is useful in acoustic engineering, audio system design, or noise analysis. For example, if two identical machines operate simultaneously, the total SPL will be the value of one plus 3 dB. Note that the calculator assumes the sources are in phase and in unobstructed environments, which may affect accuracy in real-world scenarios.
To use the calculator, input the SPL of a single source, and the result will be displayed automatically. Avoid using excessively high values without considering hearing safety limits. Additionally, the tool does not account for distance attenuation or material absorption, factors that may reduce the total SPL in enclosed spaces.
Frequently asked questions
Why does adding two identical sound sources increase by 3 dB?
Because SPL is logarithmic. When sound energy doubles, the measured level increases by 3 dB, not twice the original value.
Can I use this calculator for different SPL values?
No. The tool works only for identical sources. For different values, specific acoustic methods are required.
What if the sources are out of phase?
If sources are out of phase, the result may vary from 0 dB (complete cancellation) to 3 dB, depending on wave coherence.
Where is this applied in practice?
In sound system design, industrial noise analysis, and environmental studies where multiple sound sources operate simultaneously.