The 20th century music had rapidly changing meters. 20th century music relys less on melodies that are easy to sing and remember. This contrast to the Romantic music. In the 20th century music composers used tone color mor than ever. They used it in creating variety, continuity and mood.
Composers often draw hard drumlike sounds from the piano.
12 tone music orgainzes pitch in a composition by using a systematized form of atonality. In a 12 tone composition, the ordering or unifying idea is called a tone row, set or series. Schoenberg, Stravensky, and Webern used the 12 tone system. Schoenberg had the most impact because he came up with the 12 tone system and created atonal works for a full orchestra. OP 16 is an example of a a totally new idea in music for the time.