Insitute for Numismatic and Philatelic Studies
The Newman Numismatic Portal has recently digitized audio recordings from a home study class by the Institute for Numismatic and Philatelic Studies. George Mallis is the speaker for Lesson 5, and Leroy Van Allen for Lesson 10. These were made in 1981, and parts may have compromised audio quality, including the first couple minutes of Leroy's first recording, but they're still fun to listen to. I haven't had the time to go all the way through them yet.
Go to the following page and search for their names: https://nnp.wustl.edu/library/multimediadetail/515000
Lesson 10 Part 1 https://nnp.wustl.edu/library/book/523097