The inverse square law is a mathematical and physical principle of nature that is in effect all around us, all the time. The light from an overhead fixture, the beeping from an alarm clock, and the heat from a fire are all under the control of the inverse square law. Be it light, sound, heat, or any other kind of energy, the farther away the energy source is, the weaker it seems to be.
But by exactly how much does this energy change with distance? If the distance to a foghorn is doubled, will the sound decrease by half? By 25%? By more?