Now nearly four decades old, the debate over so-called "backmasking" has been resurrected thanks to the advent of digital music and easy-to-use editing software. No more spinning that vinyl record backward on a turntable: Satan, apparently, has gone binary.
Enter "backmasking" into the Google search engine and nearly 9,000 sites pop up. One of them is "Stairway to Heaven: Backwards" (http://jeffmilner.com/backmasking.htm), a site established by Jeff Milner, a 25-year-old student, part-time lifeguard and bed salesman.
"As a kid, a cousin of mine told me he took his 'Stairway to Heaven' record and played it backwards hearing some kind of satanic message," Milner says. "I never had a chance to hear it myself. . . . Then when the technology came along to do it on the computer, I jumped at the chance."
He copied the song from the 1971 Led Zeppelin al- bum onto his hard drive, then used the Windows Sound Recorder application to reverse it. He found what sounded like lines about the devil. Well, sort of.
At first listen, the clip, among many on his site, does seem to have someone muttering about "my sweet Satan." Play it again, with the supposed reverse lyrics on-screen, and it seems a clearer, more complete ode to ol' Beelzebub.
"The response I received was amazing," says Milner, who nonetheless remains skeptical that the message is more than coincidental or a chance combination of backward syllables sounding like speech. "Within a month or so, my e-mail was being flooded."
In the little more than a year, Milner has logged nearly 2.5 million unique visitors just on the "Stairway to Heaven" clip.
There are other examples, but you will need to strain to make out "Paul is a dead man . . ." from a backward portion of "I'm So Tired" off the 1969 Beatles album, "Abbey Road." And while there might be a secretive "It's fun to smoke marijuana" in Queen's "Another One Bites the Dust," it takes a sensitive ear, indeed, to catch "I love Satan" secreted beneath the "Pokemon Rap."
Milner finds the backmasking phenomenon fascinating, but has concluded it's "nothing more than the power of suggestion."
Experts tend to agree. In their 1985 study, collegiate psychologists John Vokey and Don Read played Queen's "Another One Bites the Dust" and the 23rd Psalm backwards; subjects typically did not hear hidden phrases until Vokey and Read suggested them.
"The short answer is that delivering subliminal messages via backward masking is totally and ridiculously impossible," says Mark D. Allen, a psychology professor at Brigham Young University.
"The brain just doesn't work that way," he notes.
Adds Don Sinex, a Utah State University colleague: "Speech played backwards is unintelligible, even in the absence of a competing sound. It's simply not plausible to think that backward speech could be understandable when embedded in music."
Well, unless the messages are intentionally dubbed in by musicians as either an artistic statement, or a gibe at particularly obsessive fans.
Pink Floyd's song "Empty Spaces," for example, hides a "gotcha" comment: "Congratulations! You have just discovered the secret message."
Music parodist Weird Al Yankovic hid "Satan eats Cheez Whiz" in his song, "Nature Trail to Hell." And even the Christian rock group Petra got into the act with its hit, "Judas Kiss," reverse-recording the message: "What are you looking for the devil for, when you ought to be looking for the Lord?"
Still, for a segment of conservative Christian America - even some Muslims - backmasking remains a spiritual threat.
On his Web site http://rossolson.org, Christian commentator Ross Olson allows that some bands - think Marilyn Manson, or Ozzy Osbourne in his early, crazy days - created intentionally dark imagery "as a publicity stunt, but many have gotten deeply into occult symbols . . .
"Their music appeals to youth and their beliefs and lifestyle are imitated," he warns.