Sound opened new possibilities for bringing previously unheard voices and languages to Hollywood. The precursor was definitely radio, which was broadcasting regional songs (for example, mountain and western music on shows like The Grand Ole Opnl) and ethnic humor (in exaggerated Jewish, Mexican, Italian, and Irish accents) to widely scattered homes where such entertainment had never before been heard. The transition to sound in film coincided with a wave of enthusiasm among white audiences for entertainment performed by African Americans. Many listeners liked traditional spirituals and minstrel acts, but the jazz Age took its name from the most popular music of all. The motives for this admiration, the subject of considerable speculation, are far from clear. Was this interest driven by curiosity and respect for black culture-as in Rouben Mamoulian's successful Broadway staging of Porgy' Or was it an effort to contain or exclude...