Noise Attenuation with Distance Calculator

Noise Attenuation with Distance Calculator

Sound pressure level drops predictably as you move away from a point source - this calculator applies the inverse square law used in acoustics and environmental noise assessment to estimate that drop-off.

L2 = L1 - 20 × log₁₀(D2 / D1)

Example

A source measured at 90 dB at 1 meter - what's the level at 10 meters?

L2 = 90 - 20 x log10(10/1) = 90 - 20 = 70 dB

The "6 dB Per Doubling" Rule

This formula produces a well-known acoustics rule of thumb: sound pressure level drops by approximately 6 dB every time the distance from a point source doubles, in ideal free-field conditions (no reflecting surfaces or obstructions) - a direct consequence of sound energy spreading over an increasingly larger spherical surface area as it radiates outward.

Real-World Caveats

Actual environmental noise measurements often deviate from this idealized model due to ground reflection, atmospheric absorption, wind and temperature gradients, and physical barriers (walls, buildings, terrain) - professional environmental noise assessments typically apply additional correction factors on top of this basic inverse square law estimate to account for these real-world effects.