How did radio, phonographs, and television help popular music spread in the 20th century?

In the 20th century, the phonograph, radio, and television fundamentally transformed the dissemination of popular music by shifting the primary medium of consumption from sheet music to recorded sound and visual performance.12

• Phonographs: By 1930, phonograph records replaced sheet music as the chief source of music in the home, allowing individuals without formal training to engage with music. The development of the microphone further enabled intimate vocal techniques that were commercially adaptable.12
• Radio: Radio broadcasting reached rural communities, aiding the spread of new styles like country music. By the 1950s, the rise of "Top 40" programming and the influence of disc jockeys helped popularize rock and roll, while portable transistor radios made music accessible outside the home.123
• Television: TV served as a powerful promotional tool, with appearances on programs like The Ed Sullivan Show launching stars like Elvis Presley. Later, the 1981 launch of MTV solidified the music video as a defining element of the industry, while cable television allowed for the targeting of specialized audiences.45