This first came to light with The Beatles in the late sixties,I was there for the "Paul is dead thing."It was pretty creepy and you may not remember a time when many people in the US were burning beatles records.1966 was their last tour here and they did it in fear for their very lives.For the most part I would say that it is a load of crap.It really seems to me that rock musicians such as myself would just put it right out front.Reverse speech is a natural occurence.Maybe some did,how they did would be interesting from a scientific viewpoint.Did they say the satanic stuff first and then reverse the recording to see what lyrics they would have to write out front to get the message there?Jimi Hendrix I would say was the most far out guy for studio experimentation.On the song "Are you Expierenced" you can blatenly hear backwards guitsr solos which do sound really cool.The reversed sustain.I would like to try that.And I am going to call one of my engineers,the studio I largely work at is the Top "Death Metal" recording facility.My friends from the group "Obituary" did their best work there.John Tardy was the first vocalist to sing like that,sometimes it sounds like he is singing backwards and you may find an uplifting christian message in there.In real life he and his brother Donald,one of the greatest drummers in the world,are the sweetest two all-american kids you would ever meet.And a lot of fun to hang out with.They think that I am weird!Anyhow let me call an engineer and ask him if he has,or has seen it being done.