The Electrical Experimenter, February, 1917, page 748:

TUFTS  COLLEGE  SENDS  MUSIC  BY  RADIO.

    An interesting development in the field of wireless has been the transmission of music by wireless telephones. Very special apparatus is necessary at the sending station, but ordinary wireless receiving sets are required in order to hear the music.
    At Tufts College experimenters are using a De Forest oscillion bulb to provide the necessary high frequency current. They have improved the method of introducing the voice to the high frequency. By this method music may be reproduced by a phonograph and transmitted hundreds of miles by wireless and yet sound better and clearer than if the hearer were only a few feet from the phonograph.
    The scratching noise is entirely eliminated, for it is not transmitted by the wireless sender.