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Among the soothing voices at WPFW 89.3 FM, William Barlow has been introducing audiences to world music for about 20 years. And, like his colleagues at the station, he does it for free. Each Tuesday evening, Barlow schleps a crate of the collection du jour into the station. He may throw down a Native American hymn, maybe follow it with a Celtic tune, and then spin some Os Mutantes. “I love doing this stuff,” he says. “There’s so much music out there to explore.” He also loves the medium of radio—which explains his other occupation.

Barlow is a radio historian. He’s written about the blues and is a faculty member of the Department of Radio, Television and Film at Howard University. These days, he’s about black radio—not just as an urban phenomenon but as a historical paradigm. His new book, Voice Over: The Making of Black Radio (Temple University Press), draws a connection between the rise of black voices on the air and the emergence of black ideas in the forefront of American culture.

The book traces the early years of black radio, from the exploitative days of blackface before World War II all the way up to modern-day radio empires like that of Tom Joyner. For most of the 20th century, network radio, Barlow says, was a Jim Crow operation. “[Commercial] sponsors were unwilling to sponsor network shows that featured artists like Louis Armstrong because they feared their products would be associated with black people.” The irony is that black communities embraced radio even more than their white counterparts.

“After World War II,” says Barlow, “black radio becomes the major source of news and culture for black people—more important than the black press. It continues the black oral tradition.” To this day, black audiences listen to radio at a higher proportion than members of other ethnic groups, he points out. “Radio is the real glue of the black community today,” he says.

Barlow’s credentials go back to the late ’50s. He spent his teenage years in Heidelberg, Germany, as an Army brat, passing his nights by the radio, listening to the music broadcast out of the Armed Forces Radio network. “I got turned on to black radio at that time,” he recalls. His ears were accustomed to hearing white voices like Pat Boone “singing” “Tutti Frutti.”

When he returned to the United States, he heard Little Richard’s version. “Damn,” he recalls thinking, “I’ve been listening to Brand X all this time.”—Guy Raz