Sound Attenuation – Inverse Square Law

In order to determine an estimate of a sound pressure level at a distance the Inverse Square Law can be used. In terms of the propagation and attenuation of sound, the inverse square law is a principle in physics whereby a point source emits a sound wave uniformly in all directions (essentially spherically), where the intensity of the sound wave energy at any given point away from the source is diminished as a function of the total surface area of the sphere coincident with that point.

To determine the sound attenuation over a distance using the inverse square law, an idealisation needs to be made in which there are no reflective surfaces or barriers between the source and the location at which the sound level is being determined.

According to the inverse square law, it can be shown that for each doubling of distance from a point source, the sound pressure level decreases by approximately 6 dB. Examples of points sources could include valves, small pumps and motors.

Calculate the sound attenuation using either metric or imperial units of distance (i.e. metres or feet).

We have created YouTube videos explaining the theory of the tool as well as a short clip demonstrating how the tool works. Click on the links below to watch our videos, subscribe to our channel and turn on post notifications to never miss an update!


Is there an environmental engineering tool you would like to see at, or do you have recommendations on the tools we have? Please complete our online tools feedback form.


Please note that this or any other calculators on the tools room are for information only. WKC Group has endeavoured to ensure that the information presented here is accurate and that the calculations are correct, but will not accept responsibility for any consequential damages, faults or human errors that may arise from the use of formulas, inventories and values.