Yes, lots of audio recordings authenticated by unnamed intelligences sources. Always unnamed. Nobody in a Cabinet position ever has a comment about it.

A company, The Dalle Molle Institute for Perceptual Artificial Intelligence that does development work for voice recognition systems used by international banks, analysed one of those 'authenticated' tapes. They were 100% sure the tape was NOT OBL. This was after 'unnamed US intelligence sources' authenticated the tape. But then when asked to verify a second tape a few months later they refused to do the work at all.

http://newsmine.org/archive/9-11/binladen/after-death/support-iraq-tape-feb03/swiss-wont-verify.txt