Francis McCarty -- the original version of this article misspelled his last name as "McCarthy" -- used a high-frequency spark for his audio transmissions, which wasn't too practical for high quality sound. But this young genius never got the chance to perfect his ideas, for he died fewer than three years later. For more information about Francis McCarty's short life, see John F. Schneider's Francis McCarty, Early San Francisco Radio Experimenter.
 
New York Times, November 30, 1903, page 1:

BOY'S  TALE  OF  INVENTION.
_________

F.  J.  McCarty  of  San  Francisco  Claims  Success  in  Wireless  Telephoning.

Special  to  The  New  York  Times.
    SAN  FRANCISCO, Nov. 29.--Francis J. McCarty, a fifteen-year-old boy of this city, has, it is asserted, invented a system of wireless telephoning which he has tested and found practicable for sending messages four miles.
    When thirteen years old McCarty entered a dry goods house as a clerk, and his employer helped him to buy books and to make electrical experiments. He first, it is stated, began developing the wireless telephone in his own home, and recently he raised a thirty-foot pole on top of his house, and by the aid of another pole four miles away he set up communication. He says:
    "I used the Hertzian wave principle as a basis for my investigations, and the fact that I have telephoned over four miles proves that my theory is correct."