During the Jazz Age and Great Depression, radio broadcasters did not conjure their listening public with a throw of a switch; the public had a hand in its own making. "The Listener's Voice" describes how a diverse array of Americans boxing fans, radio amateurs, down-and-out laborers, small-town housewives, black government clerks, and Mexican farmers participated in the formation of American radio, its genres, and its operations.

Before the advent of sophisticated marketing research, radio producers largely relied on listeners' phone calls, telegrams, and letters to understand their...