The NBC broadcast that Steve describes was made on December 27, 1934. Our copy was apparently transcribed from a pair of aluminum discs not in our collection. Here's the description from the Library of Congress' online catalog (full record at http://lcweb5.loc.gov/cgi-bin/starfinder/688188/sonic.txt ):
"Interview with Charles E. Apgar who for fourteen nights around June 18, 1915 recorded messages broadcast by a German owned and operated radio station in Sayville, Long Island. The U.S. government asked Apgar to do this because the station was broadcasting encoded information to Germany about American shipping for German submarines off-shore. Based on Apgar's recordings, the government seized the station on July 8, 1915. Apgar used his homemade radio receiver and an Edison cylinder phonograph to record the messages. During the interview he plays two of the original cylinders. "
The interviewer was George Hicks, best remembered for his shipboard D-Day broadcast.
Library of Congress