The practice of using musical material to represent a specific character or object in an opera: impressionism

expressionism

dadaism

leitmotif

The practice of using musical material to represent a specific character or object in an opera is a leitmotif :3

Explanation:

:3

pitch- the definition of pitch is as follows:

"the quality of a sound governed by the rate of vibrations producing it; the degree of highness or lowness of a tone."