How does music of the early 20th century differ so radically from genre to genre?

During the 20th century there was a large increase in the variety of music that people had access to. Prior to the invention of mass market gramophone records (developed in 1892) and radio broadcasting (first commercially done ca. 1919–20), people mainly listened to music at live Classical music concerts or musical theatre shows, which were too expensive for many working class people; on early phonograph players (a technology invented in 1877 which was not mass-marketed until the mid-1890s); or by individuals performing music or singing songs on an amateur basis at home, using sheet music, which required the ability to sing, play, and read music.

Explanation:

Im probably older then you and I know this stuff.

b.) a 3-d model