How to Use the Noise Distance Attenuation Calculator
Sound naturally gets quieter as you move away from its source, and physics describes this with the inverse square law. This calculator takes a reference distance and the noise level (dB) measured there, plus the distance you actually want to check, and uses the formula 20×log10(distance ratio) to calculate the change in noise level and the expected sound level at the new distance. Doubling the distance, for example, reduces noise by about 6 dB in theory.
This formula assumes a point source radiating evenly in all directions under free field conditions. If the distance you're checking is closer than the reference distance, the calculation correctly shows noise getting louder instead. It's useful for estimating how loud construction noise might sound to a nearby unit, or roughly how much quieter a speaker or exhaust fan becomes once you step a certain distance away.
Real-world results can differ from the theoretical value because of reflections and absorption from buildings, walls, and terrain, as well as wind direction and other variables. For an accurate measurement, using a sound level meter on site is always the most reliable option.
Frequently Asked Questions
For a point source, doubling the distance reduces noise by about 6 dB. This comes from the inverse square law formula, 20×log10(distance ratio).
This formula assumes an open, obstruction-free point source (free field conditions). Indoor spaces are affected by reflection and absorption, and outdoor results can vary with terrain and wind, so actual attenuation may differ.