The loudness of sound is determined, in turn, by the intensity of the sound waves. Intensity results from two factors: the amplitude of the sound waves and how far they have traveled from the source o...The loudness of sound is determined, in turn, by the intensity of the sound waves. Intensity results from two factors: the amplitude of the sound waves and how far they have traveled from the source of the sound. The same amount of energy is spread over a greater area, so the intensity and loudness of the sound is less. Intensity of sound results from two factors: the amplitude of the sound waves and how far they have traveled from the source of the sound.