Despite her claim to be "The Original Radio Girl", Vaughn de Leath actually wasn't the first female singer to broadcast for Lee DeForest -- according to him, in 1907 a "contralto singer named Van Boos" (Eugenia Farrar) sang "I Love You Truly" over an experimental New York City station in 1907, and Mariette Mazarin followed in 1910.
 
Zanesville (Ohio) Times-Signal, October 16, 1927, Section 2, page 14:
 
FIRST  WOMAN  AT  THE  MIKE  STILL  ON  JOB
    New York, Oct. 15.--The "Original Radio Girl" refuses to give up her crown of originality.
    So since many other "girls" have come forth to contest the claims of Vaughn de Leath, Vaughn has decided to hurl out a more drastic challenge.
    She now becomes "The Original Radio Favorite."
    And who, cries Vaughn, is there to contest this right of hers?
    To prove that she is the one and only, Vaughn goes back to ancient history--ancient at least, in the history of radio broadcasting. In fact, it's prehistoric so far as popular radio is concerned.
Sang  for  De  Forest
    "My first program," the indefatigable Vaughn recalls, "went on the air back in 1919 at the old experimental studio of Dr. Lee De Forest, in the World Tower building."
    That's a whole year before the first broadcasting station went on the air in an experimental way. It was crude broadcasting in 1920, compared with the kind of work done only seven years later. But when Vaughn de Leath sang her jazzy tunes to satisfy a whim of De Forest, transmission was much cruder. She recalls:
    "The studio at that time was a very small room, hardly any bigger than a fair-sized closet, and the broadcasting was done by means of an instrument which greatly resembled an old fashioned phonograph horn."
    What a contrast to the elaborate studios of today!
    Now Vaughn de Leath sits at the piano in a noiseless, echo-proof studio, singing into a modern sensitive microphone, and is sure of being heard by thousands of fans throughout the country. For she is a favorite on the blue network of stations which is led by WJZ in New York.
Still  New  to  Her
    She's still as exuberant over this form of entertainment as she was the first day she sang into De Forest's improved broadcaster.
    "I never fail to feel a shiver of joy when I enter a broadcasting room," she says. "My enthusiasm for it is boundless, for each time I feel it is a new experience. My underlying thought always is that, somewhere or other in the extensive ether, there is someone who has never heard me before.
    "That, together with the thought of my faithful listeners, gives me an incentive always to do my best."
    Vaughn de Leath has closer ties to broadcasting than her claim as an old favorite. She remembers when she was managing director of a broadcasting station. It was station WDT, now defunct. Here also she claims being the first woman radio director.
Vaughn de Leath