A "variation" is just that ... a variation on the original theme, where the original tune or melodic idea is much the same, but the accompaniment may differ slightly or greatly.
Another variation is to change the cantus firmus to another part, other than the soprano line, for instance.
It makes it sound good
The use of different keys in a piece of music allow the sound and overall mood of the piece to change. The use of modulation (the section of the piece where the key starts to change, or modulate) propels the music forward, giving it life and lift.
The round is a very primitive form of musical structure. It goes back before composers were identified by name.
Paraphrase
The Composers Quartet was created in 1965.
It makes it sound good
Cesar Franck for one ... Prelude, Fuge et Variation, for classical organ.
The use of different keys in a piece of music allow the sound and overall mood of the piece to change. The use of modulation (the section of the piece where the key starts to change, or modulate) propels the music forward, giving it life and lift.
Minimalist composers use repeating rhythms and harmonies that change gradually.
cos they do
Guerrilla Warfare
The round is a very primitive form of musical structure. It goes back before composers were identified by name.
You can use it the varying of length
Holding the audience's attention may require a bit of tone variation. The bobcat is a variation of the lynx.
Franco of Cologne
Italians
Franco of Cologne