Peter Hirtle in Archives-L:
There is good and bad news. The good news is that since WWI occurred before 1923, sheet music from that period would be in the public domain in the U.S.
The bad news is that no sound recording made before 1972 has federal copyright protection. They are instead protected by state common law copyrights, and will not enter the public domain until in most cases 1 January 2049, regardless of when they were recorded. (I have a section on sound recording copyrights in the chart at http://copyright.cornell.edu/resources/publicdomain.cfm ). Note that state protection is afforded even to European recordings, most of which enter the public domain in their home country after 50 years.
In theory, then, copying or performing a sound recording made during WWI could be a violation of state common law copyrights. If the recording was made after 1972, you could be infringing on the federal right of public performance.
You have three options:
1. Have local musicians record for you new versions of World War I songs (securing their permission to use the recordings as you see fit).
2. Determine that your use is authorized under Wyoming law. This is quite possible – many state laws are primarily anti-bootlegging statutes, and may not care about non-commercial performance in an exhibition.
3. Ignore the law. Note that many companies do exactly that, releasing copies of early recordings confident in the idea that no one cares about the copyright in those recordings anymore. Same thing with the many web sites that include recordings of WWI music. I wrote a blog posting awhile ago called „Real Life Risk Assessment“ (found at http://blog.librarylaw.com/librarylaw/2009/10/real-life-risk-assessment.html ) praising the Judaica Sound Archives for digitizing and making available much of their holdings, in spite of the fact that little is in the public domain. You could do the same.
For more on the copyright of early sound recordings, I highly recommend Peter Jaszi’s CLIR report, „Protection for Pre-1972 Sound Recordings under State Law and Its Impact on Use by Nonprofit Institutions: A 10-State Analysis“ at http://www.clir.org/pubs/abstract/pub146abst.html and June Besek’s CLIR report „Copyright Issues Relevant to Digital Preservation and Dissemination of Pre-1972 Commercial Sound Recordings by Libraries and Archives“ at http://www.clir.org/pubs/reports/pub135/contents.html