Inverse Square Law — Distance

Inverse Square Law — Distance

NO-08
ASPCSPFoundational

Formula
dB₁ = dBo + 20×log₁₀(do/d1)
When to Use

Calculate how noise level changes with distance from a point source in a free field.

Symbol Legend
SymbolMeaningUnitNote
dB₁Sound level at new distancedB
dBoSound level at original measurement pointdB
doOriginal measurement distanceft or m
d1New distanceft or m

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