An example of automatic alignment of audio for the purpose of comparing recordings, using Sonic Visualiser with the MATCH audio alignment plugin. This is an example with three different historical recordings of the same classical work.
The three audio recordings are loaded, and are first played all together (cacophonously, because they have quite different timing), then solo'ed but unaligned. Then we hit the magic Align button which calculates a time-alignment, and play again with alignment, switching between tracks at will while remaining at the same point in the underlying musical score.
Sonic Visualiser is a Free Software cross-platform audio analysis program from Queen Mary, University of London. See http://www.sonicvisualiser.org/ for more information, downloads, etc., and http://sonicvisualiser.org/doc/tutorial/en/sv-alignment.pdf for a tutorial about using it for audio alignment.