Decibel Addition Calculator
Calculate the combined sound pressure level when two or three noise sources are added together using logarithmic addition.
How to Use the Decibel Addition Calculator
- Enter the SPL of the first noise source in dB.
- Enter the SPL of the second noise source in dB.
- Optionally enter a third source, or leave it at 0 to ignore it.
使用场景
- •Predicting combined machinery noise levels in factories.
- •Acoustic assessments for occupational health and safety.
- •Audio engineering: combining speaker or amplifier noise floors.
公式
dB_total = 10 × log₁₀(10^(dB₁/10) + 10^(dB₂/10) + 10^(dB₃/10)). Sources with dB = 0 are ignored.
常见问题
Why can't you just add decibels directly?
Decibels are a logarithmic scale. Adding two identical 70 dB sources gives ~73 dB, not 140 dB. You must convert to linear power, sum, then convert back.
What if I add two equal sound sources?
Two identical sound sources always produce 3 dB more than a single source (e.g. 70 + 70 = 73 dB).
Is this calculator free?
Yes, all OhMyCalc calculators are completely free to use.