Resources
History of sound recording
Here links to some PDFs for some primary sources in the history of sound recording that should be more freely available than they currently are.
Berliner, Emile. “The Gramophone: Etching the Human Voice.” Journal of the Franklin Institute 125, no. 6 (June 1, 1888): 425–47. https://doi.org/10.1016/0016-0032(88)90219-0.
Smith, Oberlin. “Some Possible Forms of Phonograph.” The Electrical World 12, no. 10 (September 8, 1888): 116–117.