What era or time frame has music made significant and rapid changes?

Afilm, like any other artwork, can never be totally understood and appreciated through critical analysis, no matter how complete or astute, although such analysis can open up new levels of meaning and appreciation for the sensitive viewer.

Behaviorists focus on behaviors that.. a are observable b are caused by unconscious desires and conflicts c people become consciously aware of d can be categorized into a theoretical system

Which of the following american composers was not influenced by jazz? a. george gershwin b. william grant still c. amy beach d. aaron copland