An “archive or over 3,000 Yiddish folk and art songs, theater music, comedy and klezmer music in songbooks, reference works and sound recordings.” There is a searchable trilingual database in Yiddish, Hebrew and English with more than 28,000 entries. Over 1,800 recordings are in the collection.
http://dewey.library.upenn.edu/sceti/freedman/index.cfm?nav=freedman