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.
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".
Backmasking has been a controversial topic in the United States since the 70s and popular during the 80s and 90s, when allegations from Christian groups of its use for Satanic purposes were made against prominent rock musicians, leading to record-burning protests and proposed anti-backmasking legislation by state and federal governments.
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.
His design overtook the Edison phonograph in the 1920s, partly because Berliner's patent expired in 1918, leaving others free to use his invention.
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.
The backwards content contained a hidden visual story and the words 'music unleashes you' embedded into the reversed audio track.
Backmasking has been used as a recording technique since the 1960s.
In the era of magnetic tape sound recording, backmasking required that the source reel-to-reel tape actually be played backwards, which was achieved by first being wound onto the original takeup reel, then reversing the reels so as to use that reel as the source (this would reverse the stereo channels as well).
Digital audio recording has greatly simplified the process.
In the 1973 film The Exorcist, a tape of noises from the possessed victim was discovered to contain a message when the tape was played backwards.
Gibb played the song backwards on his turntable, and heard "Turn me on, dead man ... Initially, the search was done mostly by fans of rock music; but, in the late 1970s, 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.
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.
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.
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". 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 Mc Cartney had died, and claimed that the Beatles song "Revolution 9" contained a backward message confirming the rumor. After Gibb's show, many more songs were found to contain phrases that sounded like known spoken languages when reversed.
Backmasking is a recording technique in which a sound or message is recorded backward onto a track that is meant to be played forward.
Backmasking is a deliberate process, whereas a message found through phonetic reversal may be unintentional.
Backmasking was popularised by the Beatles, who used backward instrumentation on their 1966 album Revolver.
Artists have since used backmasking for artistic, comedic and satiric effect, on both analogue and digital recordings.
The technique has also been used to censor words or phrases for "clean" releases of explicit songs.
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.
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.
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.