of the expression) in interviews, and explained the term as follows: "Rock ’n roll is really swing with a modern name. It began on the levees and plantations, took in folk songs, and features blues and rhythm". In discussing Alan Freed's contribution to the genre, two significant sources emphasized the importance of R&B in its development. After Freed was honored with a star on the Hollywood Walk of Fame in 1991, the organization's website offered this comment: "He became internationally known for promoting African-American rhythm and blues music on the radio in the United States and Europe under the name of rock and roll". Some years later, Greg Harris, then the Executive Director of the Rock and Roll Hall of Fame, said to CNN: "Freed's role in breaking down racial barriers in U.S. pop culture in the 1950s, by leading white and black kids to listen to the same music, put the radio personality 'at the vanguard' and made him 'a really important figure'". Development of the musical style Rock and roll music principally emerged from the influences of blues and rhythm and blues music. The genre was certainly strongly influenced by R&B, according to many sources, including an article in the Wall Street Journal in 1985 titled, "Rock! It's Still Rhythm and Blues". In fact, the author states that the "two terms were used interchangeably", until about 1957. Other sources listed in the article indicate that rock and roll combined R&B with pop and country music. Each musical genre developed over time through changing fashion and innovation, and each one exchanged ideas and stylistic elements with all the others. Contributions came from America's black population, with an ancient heritage of oral storytelling through music of African origin, usually with strong rhythmic elements, with frequent use of "blue notes" and often using a "call and response" vocal pattern. African music was modified through the experience of slavery, and through contact with white musical styles such as the folk ballad, and instruments, such as the Spanish guitar. New styles of music emerged among black Americans in the early 20th century in the form of blues, ragtime, jazz, and gospel music. According to the writer Robert Palmer: Rock 'n' roll was an inevitable outgrowth of the social and musical interactions between blacks and whites in the South and Southwest. Its roots are a complex tangle. Bedrock black church music influenced blues, rural