Years ago someone told me that if you played Led Zeppelin's Stairway to Heaven song backwards that you could make out "satanic messages". It is not my opinion that Led Zeppelin and the other artists here were given some kind of evil power to make these backwards sounds have a satanic message. And, no, I did not create this to show the evils of Rock and Roll. Basically it boils down to this:

The reverse files sound cool.

The way I made these sound clips was first to get a copy of the original versions. For example I took my copy of Stairway to Heaven (I tried it once with a live version but I couldn't hear the message clearly) then opened it in a sound editing program (I used Windows Sound Recorder—but you can use the open source software Audacity), and reverse it. Crop to the place with back-masking sounds. That's it.