The fact that this article suggests that Sergeant Brass' radio concert was "probably the first in the history of that device" shows how limited was the knowledge of other radio activities, as similar experimental transmissions had been already been going on for a number of years at a variety of sites. Although the date is not mentioned in this wire service account, according to other reviews this broadcast took place on March 12, 1920.
New Castle (Pennsylvania) News, March 25, 1920, page 2:


(International  News  Service.)
    ATLANTA, Ga., March 25.--Means of sending music by wireless has been devised by Sergeant Thomas Brass, of the Georgia Tech signal unit, Reserve Officers' Training Corps. A demonstration to the Atlanta Radio club proved the success of his invention, which is epoch-making in wireless circles.
    Sergeant Brass gave a concert by wireless telephone, probably the first in the history of that device. It was to the jazzy strains of "Dardanella" that the invention was first publicly tested.
    The invention necessitates the listener using a head set to hear, but Sergeant Brass is seeking to perfect an arrangement of sounding boards which will enable an audience assembled at a designated place to enjoy music from a distance without equipping themselves with individual trappings.
    The demonstration was started at 7:30 o'clock when all radio stations in Atlanta were called and told to listen. As soon as complete communication had been established, Sergeant Brass sent "Dardanella" through the instrument without warning to the listeners. All were asked to report back what they heard with the result that the success of the invention was assured.
    Sergeant Brass tells how he conceived the idea of a radio concert in this manner:
    A station in Alabama that is on "speaking terms" with Tech Station, was having considerable trouble in hearing a conversation on the wireless telephone some time age. After having the message repeated several times the Alabama operator instructed to "sing it." Sergeant Brass, who has spent 25 years in the army, and whose singing days are but images of the past, declined to vocalize in the manner suggested, but promised to get a phonograph for him.
    "You know," he said, "the idea struck me that it might actually be done. I tried it out with the ordinary transmitter, but it wouldn't work. Not enough of the sound could be concentrated on the diaphram of the transmitter. Then I got to work and fixed it."
    What Sergeant Brass actually "fixed" was a very sensitive diaphram for a two-step amplifier receiving set. This was done only after several weeks of experimenting and hard work on the part of the entire signal unit. The work was kept strictly secret until the initial tryout was given. An ordinary phonograph was started, the transmitter set up, and--wireless music!
    On hearing the music, one of the local stations promised to entertain with a dance, the music to be furnished by radio. This will necessitate some additional fixtures, since at present the sound does not carry far enough from the receiver for dancing purposes, and it would be necessary for the dancers to wear a receiving headset.
    The possibilities of a dance were discussed, and Sergeant Brass is of the opinion that it would be possible with the proper arrangement of sounding hoards. He intends to commence work on this in the near future. Until these are made, the pleasure of wireless music will have to be confined to those who are fortunate enough to get a head set.