During World War One, numerous U.S. Navy ships were outfitted with new vacuum-tube radio transmitters, which were occasionally used to broadcast concerts to local installations, in this case from off the coast of California.
Telephone Engineer, March, 1919, page 107:

Music  by  Wireless

    The radio department of Rockwell field at San Diego gave a treat to music lovers February 2 which, so far as is known, was never tried in the world before. The treat was entitled "Moonlight Witches Dance," the music coming from the battleship Marblehead transmitted by wireless telephone.
    The affair was arranged for the concession containing the cabaret and dance, and in charge of Lieut. R. C. Roberts of the radio department. The apparatus was tuned so as to sound as if the music was in the house, and not miles away.
    Arrangements were made with the officer in charge of radio at Point Loma to cut down the spark there at regular intervals, in order to permit the use of the telephone for music without interference from outside sources. Although the apparatus can be tuned for one distance only, Lieut. Roberts would take no chances with the music being spoiled by heavy radio sparks.
    A perfect reproduction was made of tones from the Victrola aboard the Marblehead, the volume of tone being greater than the musical instrument itself.