In sound waves, height of the wave is to ________ as number of complete waves is to ________.

The correct answer focuses on the relationship between different properties of sound waves. The height of a sound wave corresponds to its amplitude, which determines the loudness of the sound. In contrast, the number of complete waves represents the frequency of the sound wave, which is related to the pitch of the sound. Therefore, the correct understanding aligns with the relationship that amplitude is associated with loudness and that frequency is associated with pitch.

In summary, when describing sound waves, height relates to amplitude and involves how loud or soft a sound is, while the number of complete cycles or waves pertains to frequency, which influences how high or low a sound is perceived.