In 1877, Thomas Edison invented the phonograph, a device allowing sound to be recorded and reproduced on a rotating cylinder with a stylus (or "needle") attached to a diaphragm mounted at the narrow end of a horn. Emile Berliner invented the familiar lateral-cut disc phonograph record in 1888.
In addition to recreating recorded sounds by placing the stylus on the cylinder or disc and rotating it in the same direction as during the recording, one could hear different sounds by rotating the cylinder or disc backwards. In 1878, Edison noted that, when played backwards, "the song is still melodious in many cases, and some of the strains are sweet and novel, but altogether different from the song reproduced in the right way". The backwards playing of records was advised as training for magicians by occultist Aleister Crowley, who suggested in his 1913 book Magick (Book 4) that an adept "train himself to think backwards by external means", one of which was to "listen to phonograph records, reversed". In the movie Gold Diggers of 1935, the end of the dancing pianos musical number "The Words Are in My Heart" is filmed in reverse motion with the accompanying instrumental score incidentally being reversed.
The 1950s saw two new developments in audio technology: the development of musique concrète, an avant-garde form of electronic music, which involves editing together fragments of natural and industrial sounds; and the concurrent spread of the use of tape recorders in recording studios. These two trends led to tape music compositions, composed on tape using techniques including reverse tape effects.
The Beatles, who incorporated the techniques of concrète into their recordings, were responsible for popularizing the concept of backmasking. Singer John Lennon and producer George Martin both claimed they discovered the backward recording technique during the recording of 1966's Revolver; specifically the album tracks "Tomorrow Never Knows" and "I'm Only Sleeping", and the single "Rain". Lennon stated that, while under the influence of marijuana, he accidentally played the tapes for "Rain" in reverse and enjoyed the sound. The following day he shared the results with the other Beatles, and the effect was used first in the guitar solo for "Tomorrow Never Knows" and later in the coda of "Rain". According to Martin, the band had been experimenting with changing the speeds of and reversing the "Tomorrow Never Knows" tapes, and Martin got the idea of reversing Lennon's vocals and guitar, which he did with a clip from "Rain". Lennon then liked the effect and kept it. Regardless, "Rain" was the first song to feature a backmasked message: "Sunshine ... Rain ... When the rain comes, they run and hide their heads" (listen; the last line is the reversed first verse of the song).
The Beatles were involved in the spread of backmasking both as a recording technique and as the center of a controversy. The latter has its roots in an event in 1969, when WKNR-FM DJ Russ Gibb received a phone call from a student at Eastern Michigan University who identified himself as "Tom". The caller asked Gibb about a rumor that Beatle Paul McCartney had died, and claimed that the Beatles song "Revolution 9" contained a backward message confirming the rumor. Gibb played the song backwards on his turntable, and heard "Turn me on, dead man ... turn me on, dead man ... turn me on, dead man ...". Gibb began telling his listeners about what he called "The Great Cover-up", and to the original clue were added various others, including the alleged backmasked message "Paul is a dead man, miss him, miss him, miss him", in "I'm So Tired".
The "Paul is dead" rumor popularized the idea of backmasking in popular music. After Gibb's show, many more songs were found to contain phrases that sounded like known spoken languages when reversed. Initially, the search was done mostly by fans of rock music; but, in the late 1970s, during the rise of the Christian right in the United States, fundamentalist Christian groups began to claim that backmasked messages could bypass the conscious mind and reach the unconscious mind, where they would be unknowingly accepted by the listener. In 1981, Christian DJ Michael Mills began stating on Christian radio programs that Led Zeppelin's "Stairway to Heaven" contained hidden Satanic messages that were heard by the unconscious.
In early 1982, the Trinity Broadcasting Network's Paul Crouch hosted a show with self-described neuroscientist William Yarroll, who argued that rock stars were cooperating with the Church of Satan to place hidden subliminal messages on records. Also in 1982, fundamentalist Christian pastor Gary Greenwald held public lectures on dangers of backmasking, along with at least one mass record-smashing. During the same year, thirty North Carolina teenagers, led by their pastor, claimed that singers had been possessed by Satan, who used their voices to create backward messages, and held a record-burning at their church.
Allegations of demonic backmasking were also made by social psychologists, parents and critics of rock music, as well as the Parents Music Resource Center (formed in 1985), which accused Led Zeppelin of using backmasking to promote Satanism.
One result of the furor was the firing of five radio DJs who had encouraged listeners to search for backward messages in their record collections. A more serious consequence was legislation by the state governments of Arkansas and California. The 1983 California bill was introduced to prevent backmasking that "can manipulate our behavior without our knowledge or consent and turn us into disciples of the Antichrist". Involved in the discussion on the bill was a California State Assembly Consumer Protection and Toxic Materials Committee hearing, during which "Stairway to Heaven" was played backwards, and William Yaroll testified. The successful bill made the distribution of records with undeclared backmasking an invasion of privacy for which the distributor could be sued. The Arkansas law passed unanimously in 1983, referenced albums by The Beatles, Pink Floyd, Electric Light Orchestra, Queen and Styx, and mandated that records with backmasking include a warning sticker: "Warning: This record contains backward masking which may be perceptible at a subliminal level when the record is played forward." However, the bill was returned to the state senate by Governor Bill Clinton and defeated. House Resolution 6363, introduced in 1982 by Representative Bob Dornan (R-California), proposed mandating a similar label; the bill was referred to the Subcommittee on Commerce, Transportation and Tourism and was never passed. Government action was also called for in the legislatures of Texas and Canada.
The compact disc
made finding backward messages difficult, causing interest in backmasking to decline.
With the advent of compact discs in the 1980s, but prior to the advent of sound editing technology for personal computers in the 1990s, it became more difficult to listen to recordings backwards, and the controversy died down.
Although the backmasking controversy peaked in the 1980s, the general belief in subliminal manipulation became more widespread in the United States during the following decade, with belief in Satanic backmasking on records persisting into the 1990s. At the same time, the development of sound editing software with audio reversal features simplified the process of reversing audio, which previously could only be done with full fidelity using a professional tape recorder. The Sound Recorder utility, included with Microsoft Windows from Windows 95 to Windows XP, allows one-click audio reversal, as does popular open source sound editing software Audacity. Following the growth of the Internet, backmasked message searchers used such software to create websites featuring backward music samples, which became a widely used method of exploring backmasking in popular music.
In January 2014, the first backmasked video was released as part of a Grammy Awards promotional campaign. A customized video player allowed the user to watch a piece of film accompanied by a music soundtrack both forwards and backwards. The backwards content contained a hidden visual story and the words 'music unleashes you' embedded into the reversed audio track.