c. Amplitude is the third and last characteristic of sound and another part of the sine wave.
Amplitude equals the height of a wave. The height of a wave can be measured in one of two ways.
(1) First, measure from the center reference line to either the positive peak or negative peak
(fig 1-10). Measuring a wave this way is called the amplitude of a wave.
Figure 1-10. Amplitude of a wave
(2) Second, measure the height of a wave from its positive peak all the way to its negative
peak. This type of wave measurement is peak-to-peak amplitude (fig 1-11).
Figure 1-11. Peak-to-peak amplitude