The scenario of the 20th Century Classical Music Period
Right before the 20th-century music period, we were in the Romantic era. The piano was improved in several ways. A wider range of notes was added, and the tonal quality became richer and more varied. Woodwinds and brass instruments became more plentiful when the valve was developed. Romantic composers flouted Classical rules, arranging symphonies with more than four movements and composing single-movement works in various forms.
The 20th-century European political climate had a profound impact on the musical output of Western classical composers. Because the Soviet and Nazi regimes placed strict expectations on their nation’s composers, blacklisting those who did not conform and forcing them to write in styles deemed ‘acceptable’ by their governments in order to avoid persecution, composers such as Hindemith and Shostakovich wrote music that is rife with a political subtext.
After that, comes the Postmodern. Music took a new direction starting in the 1930s and continuing into the post-World War II era. Olivier Messiaen was one of the first composers to bring together classical forms with new instruments such as the ondes martenot.
Composers such as John Cage, Karlheinz Stockhausen, Philip Glass, and Steve Reich incorporated mathematical elements of chance into their compositions to create process music. John Cage had an important role. The American composer made in the 12-tone method of his teacher Schoenberg for a time, but by 1939 he had begun experimenting with increasingly unorthodox instruments such as the “prepared piano” (a piano modified by objects placed between its strings in order to produce percussive and otherworldly sound effects).
Steve Reich composed Minimalist music, which is based on repetitions and combinations of simple motifs and harmonies. Like Philip Glass, his compositions are characterized by their use of minimal materials—a single chord, a brief musical motif, a spoken exclamation—which are repeated at length with small variations introduced slowly.