Final answer:
The early twentieth-century music is marked by traits such as atonality, complex rhythms, and unconventional instrumentation, signifying a departure from traditional Western musical scales and forms. Traits not associated with this era include simple melodies and strict adherence to classical structures.
Step-by-step explanation:
During the early twentieth century, music underwent significant changes in rhythm, melody, harmony, and orchestration. Composers experimented with new structures and expressions, pushing the boundaries of traditional Western scales, notes, and tempos. The traits that describe music from this period often include atonality, complex rhythms, and unconventional instrumentation, as artists explored new realms of musical possibilities.
For instance, the move from tonal to modal characteristics, the addition of increasingly complex parts for wind instruments, and the expansion of the orchestra all reflect the era's appetite for innovation. Additionally, the focus shifted from strictly adhering to forms and easily-audible structures to pushing the limits of Romantic musical techniques and embracing nationalism as well as the early Modernist movement.
Musical traits not typically associated with the early twentieth-century music include adherence to traditional scales, simple melodies, and strict adherence to classical forms and structures. Instead, composers like Mahler and Strauss extended Romanticism, while others sought new idioms through post-Romanticism, Impressionism, and avant-garde experimentation.