Lee DeForest had been experimenting with audio broadcasting since 1907. But it was only in the fall of 1916 that he started to see technical success, as the DeForest Radio Telephone & Telegraph Company, located in the Highbridge section of New York City, began transmitting regular broadcasts from its experimental station, 2XG. The key difference between the Highbridge station success and the earlier failures was that the earlier attempts had tried to use arc transmitters, while the Highbridge station made use of the newly developed vacuum-tube transmitter. (Although vacuum-tube transmitters were based largely on improvements of DeForest's original 1906 Audion, most of the improvements were due to experimenters other than DeForest.)
 
The Music Trade Review, November 4, 1916, page 52:

COLUMBIA  USED  TO  DEMONSTRATE  WIRELESS  TELEPHONE
_______________

First  Public  Exhibition  of  the  Power  of  the  Wireless  Telephone  to  Carry  Music  Held  at  Hotel Astor  Last  Week--Dr.  Lee  De  Forest  Conducts  Demonstration  Before  Interested  Audience
_______________
 
DeForest at Receivng Apparatus     The first public demonstration of the conveying of musical tones by wireless, under the auspices of the De Forest System of Telephony and the Columbia Graphophone Co., was held at the Hotel Astor on Thursday evening, October 26, before a number of specially invited and distinguished guests. For the purpose of the demonstration a number of Columbia records were played on a Favorite Grafonola at the laboratory of the Columbia Co., 102 West Thirty-eighth street, transmitted by the De Forest Radio Telephone, and received at the wireless station at the Hotel Astor, a special receiving station having been installed in parlors A and B on the eighth floor of the hotel for the demonstration.
    In order to prove the success of the system there were practically all types of music included in the thirty-three numbers making up the program, such tenor solos by Sembach and Lazaro, soprano solos by Alice Neilson and Lucy Gates, and instrumental numbers by Leopold Godowsky, pianist; Kathleen Parlow, violinist, the Blue and White Marimba Band, Prince's Orchestra and others, and without exception the tones came from the receiver with wonderful naturalness, even the human quality of the voice being sharply defined.
    A dozen or more individual ear sets were placed around a large table, and the guests took turns listening to sections of the long program. Only on very few occasions was there any interference from general wireless stations, and this was quickly overcome by the operator.
    The demonstration, which was conducted by the inventor, Dr. Lee De Forest, in person, in co-operation with the Columbia Co., was the result of over two years of private experiment to convey music tones by wireless, and the success of the experiment was proven not only to those who listened to the demonstration, but also was emphasized by the fact that it was made possible for every wireless operator within one hundred and fifty miles to hear the concert with ordinary wireless equipment. Beginning November 1, professional and amateur wireless operators in and around New York are invited to "listen in" on the wireless transmission of the latest Columbia instrumental and operatic records sent by the De Forest Radio Telephone. Even ships at sea will be able to hear distinctly the nightly concerts in New York.
    A more powerful sending apparatus will soon be installed in the tower of the Woolworth Building, where the Columbia Co.'s offices are located, by Mr. De Forest, and will serve to carry the music to ships a thousand miles out at sea. The same principle involved in the demonstration makes it feasible for passengers on ships to hear the operas at the Metropolitan Opera House, New York; to distinguish the voices of the great artists, and even to hear the applause of the audience. This is simpler than carrying music over land, as there is less "interference" at sea.
    As in the recent epoch-making demonstration of trans-continental wireless telephone communication, the audion bulb, invented by Dr. De Forest, is the chief feature in the highly-improved apparatus used in the present tests.
    The audion is a wonderfully sensitive, incandescent lamp, containing, besides the ordinary filament, two metal plates and a metal grid of fine wire, which translates the inaudible, high-frequency electric currents that come through the ether into telephonic currents which can be heard by the human ear.
    Dr. De Forest declares that by means of his newly-developed receiving apparatus more perfect music can be heard by wireless transmission than can be conveyed by telephone wires.
    In addition to Dr. De Forest there was present at the demonstration Ed. M. Baker, advertising manager of the Columbia Graphophone Co.; G. C. Jell, superintendent of the recording department of that company, together with other Columbia officials and a large number of invited guests.
    During the course of the demonstration an elaborate buffet supper was served to the guests in the college room of the Astor, immediately adjoining the parlors where the demonstration was held.
Receiving Demonstration