From 1940 to 1970, the progress of stereophonic sound was paced by the technical difficulties of recording and reproducing two (or more) channels in synchronization, and by the economic and marketing issues of introducing new audio media and equipment. To a rough approximation, a stereo system cost twice as much as a monophonic system, since a stereo system had to be assembled by buying two preamplifiers, two amplifiers, and two speaker system. It was not clear whether consumers would think the sound was so much better as to be worth twice the price.

In 1952 Emory Cook (1913–2002), who already made fame by designing new feedback disk cutter heads to improve sound from tape to vinyl, developed a 'binaural' record. This record consisted of two separate channels cut into two separate grooves running next to each other. Each groove needed a needle and each needle was connected to a separate amplifier and speaker. The set-up was intended to give a demonstration at a New York audio fair of Cook's cutter heads rather than to sell the record. But soon afterwards the demand for such recordings and the equipment to play it grew, and Cook Records began to produce such records commercially. He recorded a vast array of sounds, ranging from railroad sounds to thunderstorms. (The term 'binaural' that Cook used should not be confused with the modern use of the word, where 'binaural' is an inner ear recording using small microphones placed in the ear. Cook used conventional microphones but gave his stereo record the name 'binaural' record.)

In 1953, Remington Records began taping some of its sessions in stereo, including performances by Thor Johnson and the Cincinnati Symphony Orchestra. Later that year, RCA Victor conducted some experimental stereo tapings with Leopold Stokowski and a group of New York musicians; in February 1954, RCA taped the Boston Symphony Orchestra conducted by Charles Münch in a performance of Berlioz's Damnation of Faust, which led to regular stereo tapings by the company. Shortly afterwards, legendary conductor Arturo Toscanini's last two public concerts were recorded on stereophonic magnetic tape. They were, however, not released in stereo until 1987 and 2007, respectively. In the UK, Decca Records began taping in stereo in mid-1954. In the early 1950s, companies such as Concertapes and RCA Victor began releasing stereophonic recordings on two-track prerecorded reel-to-reel magnetic tape. Serious audiophiles, the sort of people who would later be called "early adopters", bought them, and stereophonic sound came to at least some living rooms.^[12] Stereo recording became widespread in the music business by the fall of 1957.

The small record company Audio Fidelity released the first stereophonic disc in November 1957. Sidney Frey, founder and president, had Westrex cut a disk for release before any of the major record labels.^[13][14] Side 1 was the Dukes of Dixieland, Side 2 was railroad sound effects. On December 16, Frey advertised in the trade magazine Billboard that he would send a free copy to anyone in the industry who wrote to him on company letterhead.

That move generated a great deal of publicity.^[15] Frey promptly released four additional stereo disks. The equipment dealers had no choice but to demonstrate on Audio Fidelity Records. The first stereophonic discs available to the buying public came out in the summer of 1958.^[16] By 1968 the major record labels stopped making monaural discs.^[17][18]

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The 1940 Carnegie Hall demonstration

The Carnegie Hall demonstration by Bell Laboratories on April 9 and 10, 1940, used three huge speaker systems. Synchronization was achieved by making the recordings in the form of three motion-picture soundtracks recorded on a single piece of film. Because of dynamic range limitations, volume compression was used, with a fourth track being used to regulate volume expansion. The Dolby noise reduction system of the 1970s was a far more sophisticated version of a basically similar technique. The volume compression and expansion were not fully automatic, but were designed to allow manual studio "enhancement", i.e., the artistic adjustment of overall volume and the relative volume of each track.

The recordings had been made by the Philadelphia Orchestra, conducted by Leopold Stokowski, who was always interested in sound reproduction technology. Stokowski personally participated in the "enhancement" of the sound.

The speakers used generated 1,500 watts of acoustic power, producing sound levels of up to 100 decibels, and the demonstration held the audience "spellbound, and at times not a little terrified," according to one report.^[19] Sergei Rachmaninoff, who was present at the demonstration, commented that it was "marvellous" but "somehow unmusical because of the loudness." "Take that Pictures at an Exhibition," he said. "I didn't know what it was until they got well into the piece. Too much 'enhancing', too much Stokowski."

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Motion picture era

Bell Laboratories in New York City gave a demonstration in 1937 of two-channel stereophonic motion pictures, developed by Bell Labs and Electrical Research Products, Inc.^[20] Conductor Leopold Stokowski recorded onto a 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. The tracks were mixed down to one for the final soundtrack.^[21][22] In 1938, Metro-Goldwyn-Mayer started using three tracks to record movie soundtracks instead of one, and very quickly upgraded to four tracks. One track was used for dialogue, two for music, and one for sound effects. The purpose for this form of multi-track recording was to make mixing down to a single optical track easier and was not intended to be a recording for stereophonic purposes. The very first binaural recording MGM made (although released in mono) was "It Never Rains But What It Pours" by Judy Garland, recorded on June 21, 1938 for the movie Love Finds Andy Hardy.

The first commercial motion picture to be exhibited with stereophonic sound was Walt Disney's Fantasia, released in November 1940, for which a specialized sound process, Fantasound, was developed. Fantasound used a separate film containing four optical sound tracks. Three of the tracks were audible, and the fourth track controlled the volume level of the theater's amplifiers. The film was not a financial success, however, and after two months of road-show exhibition in selected cities, its soundtrack was remixed into mono sound for general release.

In the early 1940s, the forward-thinking Alfred Newman directed the construction of a sound stage equipped for multi channel recording for 20th Century Fox studios. Several soundtracks from this era still exist in their multichannel elements, some of which have been released on DVD including How Green Was My Valley, Anna and the King of Siam, Sun Valley Serenade, and The Day the Earth Stood Still.

The advent of magnetic tape recording made high-fidelity synchronized multichannel recording technically straightforward, though costly. By the early 1950s, all of the major studios were recording on magnetic 35mm tape for mixing purposes. Motion picture theatres, however, are where the real introduction of stereophonic sound to the public occurred. Stereo sound was proven viable with the release of This Is Cinerama on September 30, 1952. Cinerama was a spectacular wide-screen process fully comparable to today's IMAX. Cinerama required several architectural specifications for the theatre of its presentation. Cinerama's audio soundtrack utilized seven discrete magnetic sound tracks, six of them audible plus a seventh track that controlled the volume level of the amplifiers. The system was developed by Hazard Reeves, a pioneer in magnetic recording technology. By all accounts, including accounts by those who have experienced the process in rare recent showings, the sound was as spectacular as the picture and excellent even by modern standards.

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 the Warner Bros. 3-D film production of House of Wax, starring Vincent Price. The sound system, WarnerPhonic, was a combination of a 35mm magnetic full-coat that contained Left-Center-Right, in synchronization with the two, dual-strip Polaroid system projectors, one of which carried an optical surround track, and one which carried a mono backup track should anything go wrong. Only two other films carried WarnerPhonic sound, the 3-D production of The Charge at Feather River, and Island in the Sky. The magnetic tracks to these films are considered lost.

Many 3-D films carried variations on 3-track magnetic sound. Other instances include It Came From Outer Space, I, The Jury, The Stranger Wore a Gun, Inferno, Kiss Me, Kate, and many others. By the summer of 1953, the movie industry moved quickly to create simpler and cheaper wide-screen systems, such as CinemaScope, which used up to four magnetic sound tracks, and which were capable of being retrofitted into existing theatres. Cinemascope 55 was created by the same company in order to use a larger form of the system (55mm instead of 35mm), and was supposed to have had 6-track stereo, but the process proved impractical, and the two films made in it, Carousel and The King and I, were shown in 35mm Cinemascope. The premiere engagement of Carousel, however, did use 6-track stereo, on a separate magnetic sound track, and a 1961 re-release of The King and I, with the film "blown up" to 70 mm, also used a six-track stereo soundtrack.

Cole Porter memorialized the era in a 1957 song:

If Zanuck's latest picture were the good old-fashioned kind,

There'd be no one in front to look at Marilyn's behind.

If you want to hear applauding hands resound

You've gotta have glorious Technicolor,

Breathtaking Cinemascope and

Stereophonic sound.

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Early broadcasting in stereo

Radio: The BBC's experimental transmitting station 5XX in Daventry, Northamptonshire, made radio's first stereo broadcast in December 1925, of a concert conducted by Sir Hamilton Harty from Manchester, with 5XX broadcasting the right channel nationally by long wave, and local BBC stations broadcasting the left channel by medium wave. The BBC repeated the experiment in 1926, using 2LO in London and 5XX at Daventry. Following experimental FM stereo transmissions in the London area in 1958, and regular Saturday morning demonstration transmissions using TV sound and medium wave (AM) radio to provide the two channels, the first regular BBC transmissions using an FM stereo signal began on the BBC's Third Programme network on August 28, 1962.

Chicago AM radio station WGN and its sister FM station WGNB collaborated on an hour-long stereophonic demonstration broadcast on May 22, 1952, with one audio channel broadcast by the AM station and the other audio channel by the FM station.^[23] New York City's WQXR initiated its first stereophonic broadcasts in October 1952, and by 1954 was broadcasting all of its live musical programs in stereophonic sound, using its AM and FM stations for the two audio channels.^[24]

After several years of experimental stereo broadcasts, and six competing systems, the Federal Communications Commission announced stereophonic FM technical standards in April 1961, and licensed regular stereophonic FM radio broadcasting to begin in the United States on June 1, 1961.^[25] WEFM in the Chicago area and WGFM in Schenectady, New York reported as the first stereo stations.^[26]

Television: A closed-circuit television performance of Carmen from the Metropolitan Opera House in New York City to thirty-one theaters across the United States on December 11, 1952 included a stereophonic sound system developed by RCA.^[27] The first several shows of the 1958–1959 season of The Plymouth Show (i.e., The Lawrence Welk Show) on the ABC network were broadcast with stereophonic sound in some cities, with one audio channel broadcast via television and the other over the ABC radio network.^[28] By the same method, NBC television and the NBC radio network offered stereo sound for The George Gobel Show on October 21, 1958. ABC's Walt Disney Presents made a stereo broadcast of The Peter Tchaikovsky Story, including scenes from Disney's latest animated feature Sleeping Beauty, on January 30, 1959 by using ABC-affiliated AM and FM stations for the left and right audio channels.

With the advent of FM Stereo in 1961, a small number of music oriented shows were broadcast with stereo sound using a process called simulcasting in which the audio portion of the show was carried over a local FM stereo station. In the 1960s and 1970s, these shows were usually manually synchronized with a mail delivered reel-to-reel tape to the FM station (unless the concert or music was locally originated). In the 1980s, satellite delivery of both television and radio programs made this fairly hard process of synchronization unnecessary. One of the last of these simulcast programs was Friday Night Videos on NBC, just before MTS stereo was approved by the FCC.

Cable TV systems delivered many stereo programs utilizing this method for many years until prices for MTS stereo modulators dropped. One of the first stereo cable stations was The Movie Channel, though the most popular cable TV station that drove up usage of stereo simulcasting was MTV.

MTS: Stereo for television

Main article: Multichannel television sound

Multichannel television sound, better known as MTS (often still as BTSC, for the Broadcast Television Systems Committee that created it), is the method of encoding three additional channels of audio into an NTSC-format audio carrier. It was adopted by the FCC as the U.S. standard for stereo television transmission in 1984. Sporadic network transmission of stereo audio began on NBC on July 26, 1984, with the Tonight Show, although at the time, only the NBC station in New York City had stereo broadcast capability;^[29] regular stereo transmission of programs began in 1985.

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Common usage

In common usage, a "stereo" is a two-channel sound reproduction system, and a "stereo recording" is a two-channel recording. This is a cause for much confusion, since five- (or more) -channel home theater systems are not popularly described as "stereo". It is thus worth noting that most film soundtracks are not recorded using stereo techniques, so while they are capable of stereo reproduction, most home theater systems rarely are called upon to do this.

Most two-channel recordings are stereo recordings only in this weaker sense. Pop music, in particular, is usually recorded using close miking techniques, which artificially separates signals into several tracks. The separate tracks, of which there may be eight or even 24, are then "mixed-down" into a two-channel recording. By using "left-right" panning controls, the audio engineers determine where each track will be placed in the stereo "image". The end product with this process often bears little or no resemblance to the actual physical and spatial relationship of the musicians at the time of the original performance. Indeed, it is not uncommon for different tracks of the same song to be recorded at different times, and even in different studios, and then mixed into a final two-channel recording for commercial release. Classical music recordings are a notable exception; they are more likely to be recorded "live", so that the actual physical and spatial relationship of the musicians at the time of the original performance is preserved on the recording.

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Balance

Balance can mean the amount of signal from each channel reproduced in a stereo audio recording. Typically, a balance control will have 0 dB of gain in the center position for both channels, and attenuate one channel as the control is turned, leaving the other channel at 0 dB.^[30]

See also Panning

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Other uses

"Stereo" or "in stereo" is sometimes used colloquially for when two, as distinct from one, of something are present.

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See also

• 3D audio effect
• Binaural recording
• Hi-fi
• Joint stereo
• Quadraphonic
• Stereo photography
• Stereo recording techniques
• Stereographic projection
• Subwoofer (Stereo separation)
• Surround sound

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References

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