On Christmas Eve 1906, Canadian-American inventor, Reginald Fessenden, made the first ever radio audio entertainment broadcast from Brant Rock on the coast of Massachusetts. The program included Fessenden playing “O Holy Night” on the violin and reciting a Bible passage for the holiday. Even though the main audience for this transmission was shipboard audio operators along the Atlantic Coast, it led to the beginning of entertainment radio. Fessenden was the first person to transmit the sound of the human voice without wires. But a century ago, few people were interested in buying a home radio. That is, until 1920, when Westinghouse engineer Frank Conrad began regularly broadcasting music over a frequency in Pittsburgh. The popularity of these broadcasts--as well their regularly scheduled programming-- led to the creation of KDKA, the world’s first commercial radio station. KDKA pioneered the world's first in-house in studio music ensembles, including an orchestra and a country swing band. Westinghouse became the station's first commercial sponsor, when fewer than 10 thousand US households owned receivers. More and more sponsors came on board, though, as listenership grew and transmission quality improved. By the time of FDR's Fireside Chats in the early 1930s, more than 22 million US homes owned radio. Listen to the first commercial broadcast below our gallery.