Technical News Bulletin no. 38, Bureau of Standards, June 4, 1920, pages 8-9:
13  The Transmission
of Music by Radio
         Music can be transmitted by wireless in the same manner as speech or code signals. As an incidental result of research work on radio telephony at the Bureau of Standards, it has been shown that music can be transmitted by radio without loss of quality.   The possibilities in this direction are great and very interesting.   By this means a concert given in one place may be available to those living at a distance.   Experimental concerts are at present being sent out on Friday evening from 8:30 to 11, by the Radio Laboratory of the Bureau of Standards, using a wave length of 600 meters.   One way of transmitting music has been to place a phonograph so that the sound from it will pass into the radio transmitter.   The Bureau of Standards has made an interesting improvement upon this method, which consists of substituting the carbon microphone, which is the mouthpiece of an ordinary telephone, for the vibrating diaphragm ordinarily used on the phonograph.   As a result, the phonograph sound record produces direct variations of electric current in the telephone apparatus instead of producing sound, thus while no sound is heard where the phonograph record is being played, the music is easily heard by those at the distant receiving stations.


S. W. STRATTON