In the United States, sound recordings have not entered in to the Public Domain through an expiration of their copyright protection at this time. Current copyright protections for recordings made before February 15, 1972 are valid until February 15, 2067. Recordings published between February 15, 1972 and prior to 1978 are protected for 95 years from the date of publication. Both published and unpublished recordings made in 1978 and onward are protected by copyright for either 95 years from the date published, or 70 years after the date of the composer's death.
Performers and composers may choose to put their recordings into the public domain, however. In addition, recordings made by the United State Government
Feel free to ask your Personal Librarian, or you can reach out to Mandi Goodsett, CSU's librarian with a specialization in copyright.