Add sound levels
Convert a dB difference to a ratio
Why decibels don't add normally
Decibels are logarithmic, so two 80 dB machines make 83 dB, not 160 dB: L = 10·log₁₀(Σ10^(Lᵢ/10)). Ten identical sources add 10 dB.
A 10 dB difference is 10× the power, about 3.16× the sound pressure and is heard as roughly twice as loud.
Frequently asked questions
What is 3 dB?
Twice the power – the level increase from doubling identical sources.
What is 6 dB?
Twice the sound pressure (four times the power) – the drop for each doubling of distance from a point source.