A test question I was asked earlier in the year has been hanging around in the back of my mind: "If a radio is moved 3x further away from you, how is its loudness affected?" To answer this question one needs to know what determines the loudness of sound. What determines the loudness of sound? Is the loudness of sound determined solely by the amplitude of the sound wave? I answered based on this reasoning, and said that the radio would be equally loud 3x further away because its sound waves would have equal amplitude at distances x and 3x.