Why you cannot add decibels arithmetically
Sound pressure levels use a log scale. Two equal sources add about +3 dB, not double. Use:
L_total = 10 × log₁₀(Σ 10^(Li/10))
Noise Level Addition Calculator
Noise · logarithmic addition
Combine multiple sound pressure levels: L = 10 log₁₀(Σ 10^(Li/10)).
Formula: L_total = 10 × log₁₀(Σ 10^(Li/10))
Frequently asked questions
Equal sources?
Two identical levels → +3 dB; four → +6 dB, roughly.
A-weighted?
Add levels that share the same weighting (e.g. all dB(A)).
Dose still needed?
Yes for daily exposure — use the noise exposure calculator with durations.
Reflections?
This combines free levels only — rooms add reverberant build-up separately.
