The defining feature of modern music (and modern art generally) is the breaking-down of all traditional aesthetic conventions, thereby unleashing complete freedom in all aesthetic dimensions, including melody, rhythm, and chord progression. ... Even the very notion of what constitutes "music" was redefined.
Who started modern music?
The Man Who Invented Modern Music : Interlude. Of all the architects of our modern music industry, few are more forgotten or more important than Emile Berliner.
What are characteristics of modernist music?
Technically speaking, musical modernism has three main characteristics that distinguish it from previous periods: The expansion or abandonment of tonality. The use of extended techniques. The incorporation of sounds and novel sounds in the composition.