Sound Propagation - the Inverse Square Law

Calculate sound pressure level reduction based on distance from source using the Inverse Square Law. In a free field, doubling the distance reduces sound pressure level by 6 decibels.

Calculator

Inputs

Lp1 - Sound pressure level at location 1 (dB)

R1 - Distance from source to location 1 (m)

R2 - Distance from source to location 2 (m)

Results

dL - Difference in sound pressure level-- dB

Lp2 - Sound pressure level at location 2-- dB

Distance (feet)	Sound Pressure Lp (decibel)
1.25	134
2.5	128
5	122
10	116
20	110
40	104
80	98
160	92
320	86
640	78
1280	74
2560	68
5120	62