Frank Conrad operated experimental radio station 8XK. The other concert was provided over standard amateur station 8WR, licenced to Creed McKinley Chorpening, whose last name is misspelled in this article.
Monessen (Pennsylvania) Daily Independent, December 6, 1920, page 1:

Wireless  Concert

    The radiophone or wireless telephone concert which was sent out by Mr. Frank Conrad of Wilkensburg Saturday night was enjoyed by the following Monessen boys: Elmer Elliott, Merril Kent, Paul Ely and Robert Stevens.
   The music was not played on a victrola as it usually is, but was sung directly into the transmitter by the singers themselves, a male quartette furnishing the music.
   A concert which was played by Mr. C. M. Chorphing of Connellsville was also enjoyed by the same boys. The voice over the radiophone is as clear and distinct as the ordinary telephone. Every word of the singers Saturday night could be understood. The local boys are becoming efficient wireless operators and are highly enthusiastic over their success.