Which term is used to describe the coordination and expression of sound in pitch-matching?

The term that best describes the coordination and expression of sound in pitch-matching is related to the concept of "highness or lowness of a sound." This concept refers to pitch, which is a fundamental aspect of music and sound. Pitch is determined by the frequency of the sound wave; higher frequencies result in higher pitches, while lower frequencies correspond to lower pitches.

In the context of pitch-matching, individuals use their ability to recognize and reproduce pitches accurately, showcasing their understanding of the highness or lowness of various sounds. This is crucial in music therapy, as it allows for effective communication through music and sound, enhancing therapeutic relationships and interventions.

Other options, such as volume adjustment and sound manipulation, relate more to the dynamics and physical alteration of sound rather than specifically to pitch. Imitative sound alignment might refer to mimicking sounds, but it doesn't pinpoint the essential quality of pitch specifically. Thus, the chosen term directly encompasses the fundamental principle of pitch and its critical role in musical expression and coordination.