Freed is commonly referred to as the "father of rock and roll" due to his promotion of the music and his introduction of the phrase "rock and roll" on radio in the early 1950s. Freed also made a practice of presenting music by African-American artists rather than cover versions by white artists on his radio program. Freed's career ended when it was shown that he had accepted payola, a practice that was highly controversial at the time, resulting in his being fired from his job at WABC.^[11]
In the 1950s, American radio DJs would appear live at "sock hops" and "platter parties" and assume the role of a human jukebox. They would usually play 45-rpm records, featuring hit singles on one turntable while talking between songs. In some cases, a live drummer was hired to play beats between songs to maintain the dance floor. In 1955, Bob Casey, a well-known "sock hop" DJ, brought the two-turntable system to the U.S. Throughout the 1950s, payola continued to be a problem and one result of the payola scandal was tighter control of the music by station management. The Top 40 format emerged, where popular songs are played repeatedly.
In the late 1950s, sound systems, a new form of public entertainment, were developed in the ghettos of Kingston, Jamaica. Promoters, who called themselves DJs, would throw large parties in the streets that centered on the disc jockey, called the "selector," who played dance music from large, loud PA systems and bantered over the music with a boastful, rhythmic chanting style called "toasting". These parties quickly became profitable for the promoters, who would sell admission, food, and alcohol, leading to fierce competition between DJs for the biggest sound systems and newest records.