English: A "radiophone dance" held by an Atlanta social club in May 1920 in which the participants danced wearing earphones to music transmitted from a band across town. Practical AM radio transmission of sound was made possible by the development of vacuum tube transmitters and receivers during World War 1, and by 1920, after the war, the first radio stations began experimenting with broadcasting of news and music. Radio listening exploded into a hugely popular high-tech pastime and a "radio mania" swept the country, inspiring novelty stunts like this. The Club De Vingt of Atlanta, Georgia held the dance in the roof ballroom of the Capital City Club, to music played by the Georgia Tech Band into a transmitter two miles away. The radio equipment was set up by Sergeant Thomas Brass of the Georgia Tech signals unit of the Reserve Officer's Training Corps. The music was played by a vacuum tube receiver (center) on the dance floor, but the weak audio amplifier and horn loudspeaker of the receiver, designed for individual listening, was not loud enough to be heard throughout the ballroom by the 500 club members, so the dancers farther away from the radio were provided with earphones as shown, on long cords, so they could hear the music as they danced.