Contrast the amplitude and energy of the sound waves you make when you shout across the room with the sound waves you make when you speak softly

When you speak softly, the energy in the sound waves you produce is low compared to speaking loudly (where energy is higher in the waves). Therefore, the amplitude of the sound waves of the softer sound is smaller than that of the higher voice. It is important to note that the frequency of the sound waves will be the same in the two.