Level at a new distance, then add levels

Distance change, a sum of sources, and an exposure reference are separate. The exposure math is not a health or legal verdict.

Worked example

Distance 1 1 m · 80 dB

Distance 2 2 m · 73.9794 dB

Level at distance 2 73.9794 dB

Point: Lp2 = Lp1 - 20 log10(d2/d1). Line: Lp2 = Lp1 - 10 log10(d2/d1). Both distances stay in the selected unit. Ground reflection and air absorption are not added.

Tick position is the distance. Bar length is a drawing scale capped at 120 and is not the copied value. If the number you type is already dBA, the distance result stays in that weighting. This page does not turn dB into dBA.

Worked examples

Point source 80 dB from 1 m to 2 m
Line source 80 dB from 1 m to 4 m
Two 80 dB levels added

Guides

Distance attenuation
Adding decibels
Exposure reference
No equipment table