Stereophonic sound

StereoStereophonicstereo soundstereo audio2.0stereo systemstereo speakersstereophonyPCM Stereostereo channel
Stereophonic sound or, more commonly, stereo, is a method of sound reproduction that creates an illusion of multi-directional audible perspective.wikipedia
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Monaural

MonomonophonicMonoaural
It is often contrasted with monophonic, or "mono" sound, where audio is heard as coming from one position, often ahead in the sound field (analogous to a visual field).
This contrasts with stereophonic sound or stereo, which uses two separate audio channels to reproduce sound from two microphones on the right and left side, which is reproduced with two separate loudspeakers to give a sense of the direction of sound sources.

Alan Blumlein

Alan Dower BlumleinBlumleinA. D. Blumlein
Modern stereophonic technology was invented in the 1930s by British engineer Alan Blumlein at EMI, who patented stereo records, stereo films, and also surround sound.
Alan Dower Blumlein (29 June 1903 – 7 June 1942) was an English electronics engineer, notable for his many inventions in telecommunications, sound recording, stereophonic sound, television and radar.

Harvey Fletcher

Dr. Harvey Fletcher
In the United States, Harvey Fletcher of Bell Laboratories was also investigating techniques for stereophonic recording and reproduction.
Known as the "father of stereophonic sound," he is credited with the invention of the 2-A audiometer and an early electronic hearing aid.

Fantasound

Five years later, the same system would be expanded onto multi-channel film recording and used from the concert hall in Philadelphia to the recording labs at Bell Labs in New Jersey in order to record Walt Disney's Fantasia (1940) in what Disney called Fantasound.
Fantasound was a stereophonic sound reproduction system developed by engineers of Walt Disney studios and RCA for Walt Disney's animated film Fantasia, the first commercial film released in stereo.

Fantasia (1940 film)

FantasiaSorcerer's ApprenticeThe Sorcerer's Apprentice
Five years later, the same system would be expanded onto multi-channel film recording and used from the concert hall in Philadelphia to the recording labs at Bell Labs in New Jersey in order to record Walt Disney's Fantasia (1940) in what Disney called Fantasound.
The soundtrack was recorded using multiple audio channels and reproduced with Fantasound, a pioneering sound reproduction system that made Fantasia the first commercial film shown in stereophonic sound.

Théâtrophone

This two-channel telephonic process was commercialized in France from 1890 to 1932 as the Théâtrophone, and in England from 1895 to 1925 as the Electrophone.
Ader had arranged 80 telephone transmitters across the front of a stage to create a form of binaural stereophonic sound.

Blumlein pair

BlumleinBlumlein technique
When two figure-eight microphones are used, facing ±45° with respect to the sound source, the X-Y setup is called a Blumlein Pair.
Blumlein pair is the name for a stereo recording technique invented by Alan Blumlein for the creation of recordings that, upon replaying through headphones or loudspeakers, recreate the spatial characteristics of the recorded signal.

Abbey Road Studios

EMI StudiosAbbey RoadEMI
In 1934, Blumlein recorded Mozart's Jupiter Symphony conducted by Sir Thomas Beecham at Abbey Road Studios in London using his vertical-lateral technique.
In 1934, the inventor of stereo sound, Alan Blumlein, recorded Mozart's Jupiter Symphony which was conducted by Thomas Beecham at the studios.

Bell Labs

Bell LaboratoriesBell Telephone LaboratoriesAT&T Bell Laboratories
In the United States, Harvey Fletcher of Bell Laboratories was also investigating techniques for stereophonic recording and reproduction. In 1937, Bell Laboratories in New York City gave a demonstration of two-channel stereophonic motion pictures, developed by Bell Labs and Electrical Research Products, Inc. Once again, conductor Leopold Stokowski was on hand to try out the new technology, recording onto a special proprietary nine-track sound system at the Academy of Music in Philadelphia, during the making of the movie One Hundred Men and a Girl for Universal Pictures in 1937, after which the tracks were mixed down to one for the final soundtrack.
In 1933, stereo signals were transmitted live from Philadelphia to Washington, D.C. In 1937, the vocoder, an electronic speech compression device, or codec, and the Voder, the first electronic speech synthesizer, were developed and demonstrated by Homer Dudley, the Voder being demonstrated at the 1939 New York World's Fair.

Clément Ader

Clement AderAderAder, Clement
Clément Ader demonstrated the first two-channel audio system in Paris in 1881, with a series of telephone transmitters connected from the stage of the Paris Opera to a suite of rooms at the Paris Electrical Exhibition, where listeners could hear a live transmission of performances through receivers for each ear.
In 1881, he invented the théâtrophone, a system of telephonic transmission where listeners received a separate channel for each ear, enabling stereophonic perception of the actors on a set; it was this invention which gave the first stereo transmission of opera performances, over a distance of 2 miles (3 km) in 1881.

Hazard E. Reeves

Reeves Sound StudioReeves Sound Studios
Similarly, the Cinerama audio soundtrack technology, developed by Hazard E. Reeves, a pioneer in magnetic recording, utilized seven discrete sound tracks on full-coat magnetic 35mm film, in order to envelop the theatregoer in an aural experience just as spectacular as that playing on the screen: five main channels behind the screen, two surround channels in the rear of the theater, plus a sync-track to interlock the 4 machines, which were specially outfitted with aircraft servo-motors made by Ampex.
Hazard Earle Reeves, Jr. (July 6, 1906 – December 23, 1986) was an American pioneer in sound and sound electronics, and introduced magnetic stereophonic sound to motion pictures.

Perspecta

Perspecta StereoPerspecta directional audioPerspecta Inc.
VistaVision took a simplified, low-cost approach to stereophonic sound; its Perspecta system featured only a monaural track, but through subaudible tones, it could change the direction of the sound to come from the left, right or both directions at once.
Introduced as a "directional sound system" rather than a true stereophonic sound system, Perspecta did not use discretely recorded sound signals.

House of Wax (1953 film)

House of Wax19531953 film of the same name
In April 1953, while This is Cinerama was still playing only in New York City, most moviegoing audiences heard stereophonic sound for the first time with House of Wax, an early 3-D film starring Vincent Price and produced by Warner Bros. Unlike the 4-track mag release-print stereo films of the period which featured four thin strips of magnetic material running down the length of the film, inside and outside the sprocket holes, the sound system developed for House of Wax, dubbed WarnerPhonic, was a combination of a 35 mm fully coated magnetic film that contained the audio tracks for Left-Center-Right, interlocked with the two dual-strip Polaroid system projectors, one of which carried a mono optical surround track and one that carried a mono backup track, should anything go wrong.
It was also the first 3-D film with stereophonic sound to be presented in a regular theater.

3D film

3D3-D3-D film
In April 1953, while This is Cinerama was still playing only in New York City, most moviegoing audiences heard stereophonic sound for the first time with House of Wax, an early 3-D film starring Vincent Price and produced by Warner Bros. Unlike the 4-track mag release-print stereo films of the period which featured four thin strips of magnetic material running down the length of the film, inside and outside the sprocket holes, the sound system developed for House of Wax, dubbed WarnerPhonic, was a combination of a 35 mm fully coated magnetic film that contained the audio tracks for Left-Center-Right, interlocked with the two dual-strip Polaroid system projectors, one of which carried a mono optical surround track and one that carried a mono backup track, should anything go wrong.
April 1953 saw two groundbreaking features in 3D: Columbia's Man in the Dark and Warner Bros. House of Wax, the first 3D feature with stereophonic sound.

Panavision

Panavision 3DPanaflexPanavision C, E, G series anamorphic
Major Hollywood studios immediately rushed to create their own unique formats, such as Warner Bros. Panavision, Paramount Pictures' VistaVision and Twentieth Century-Fox Film Corporation's CinemaScope, the latter of which used up to four separate magnetic sound tracks.
These included a revival of color films, three-dimensional films, stereophonic sound, and widescreen movies.

VistaVision

Vista-VisionVistaVision 8/35VV
Major Hollywood studios immediately rushed to create their own unique formats, such as Warner Bros. Panavision, Paramount Pictures' VistaVision and Twentieth Century-Fox Film Corporation's CinemaScope, the latter of which used up to four separate magnetic sound tracks.
The first of these, Cinerama, debuted in September 1952, and consisted of three strips of 35 mm film projected side-by-side onto a giant, curved screen, augmented by seven channels of stereophonic sound.

Dolby Stereo

Dolby Stereo 70 mm Six Track70mm DolbyDolby A
From then until about 1975, when Dolby Stereo was used for the first time in films, most motion pictures—even some from which stereophonic soundtrack albums were made, such as Zeffirelli's Romeo and Juliet—were still released in monaural sound, stereo being reserved almost exclusively for expensive musicals such as West Side Story, My Fair Lady, or Camelot; epics such as Ben-Hur or Cleopatra.
The optical soundtrack on a Dolby Stereo encoded 35 mm film carries not only and tracks for stereophonic sound, but also—through a matrix decoding system (Dolby Motion Picture matrix or Dolby MP ) similar to that developed for "quadraphonic" or "quad" sound in the 1970s—a third center channel, and a fourth surround channel for speakers on the sides and rear of the theater for ambient sound and special effects.

Surround sound

Surround5.1 surround sound5.1
Thus the term "stereophonic" applies to so-called "quadraphonic" and "surround-sound" systems as well as the more common two-channel, two-speaker systems.
For example, two stereo speakers with no LFE channel = 2.0

This Is Cinerama

Amid great fanfare, Stereo sound was officially proven commercially viable for the public on September 30, 1952 with the release of a Cinerama demonstration film by Lowell Thomas and Mike Todd titled This is Cinerama.
Also seen are views of Niagara Falls; a performance by a church choir (out of pace with the rest of the film, this segment is shot in black and white); a performance by the Vienna Boys' Choir; scenes of the canals of Venice; a military tattoo in Edinburgh; a bullfight in Spain; the "Triumphal scene" from Aïda; a sound demonstration in stereo; and scenes from Cypress Gardens amusement park featuring an elaborate water skiing show.

Headphones

headphoneearphoneearphones
This is usually achieved by using two or more independent audio channels through a configuration of two or more loudspeakers (or stereo headphones) in such a way as to create the impression of sound heard from various directions, as in natural hearing.
Although modern headphones have been particularly widely sold and used for listening to stereo recordings since the release of the Walkman, there is subjective debate regarding the nature of their reproduction of stereo sound.

Audio Fidelity Records

Audio FidelityAFE RecordsAudio Fidelity 24kt gold disk
In November 1957, the small Audio Fidelity Records label released the first mass-produced stereophonic disc.
They are best known for having produced the first mass-produced American stereophonic long-playing record in November 1957 (although this was not available to the general public until March of the following year).

Audiophile

audiophilesAudiophiliaaudio enthusiast
By 1953, Cook had a catalog of about 25 stereo records for sale to audiophiles.
An audio system typically consists of one or more source components, one or more amplification components, and (for stereo) two or more loudspeakers.

Signal

signalselectrical signalsignaling
The two signals were sent out over separate AM station bands.

One Hundred Men and a Girl

100 Men and a Girl
In 1937, Bell Laboratories in New York City gave a demonstration of two-channel stereophonic motion pictures, developed by Bell Labs and Electrical Research Products, Inc. Once again, conductor Leopold Stokowski was on hand to try out the new technology, recording onto a special proprietary nine-track sound system at the Academy of Music in Philadelphia, during the making of the movie One Hundred Men and a Girl for Universal Pictures in 1937, after which the tracks were mixed down to one for the final soundtrack.
The music was recorded in multi-channel stereophonic sound but released in monaural sound; three years later Stokowski and the Philadelphia Orchestra appeared in the first feature film to be presented in stereo, Fantasia.

Dolby Digital

Dolby Digital 5.1AC3AC-3
Dolby Stereo was succeeded by Dolby Digital 5.1 in the cinema, which retained the Dolby Stereo 70mm 5.1 channel layout, and more recently with the introduction of digital cinema, Dolby Surround 7.1 and Dolby Atmos in 2010 and 2012 respectively.
Mono and stereo modes are also supported.