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Highlights in the History of Multichannel Sound* EMIL TORICK, AES Fellow
Santa Barbara,
CA 93110, USA
Despite the achievements of many distinguished researchers over a period of more than a century, the audio industry has never been able to define a viable business in multichannel sound. Except for cinema applications, two-channel stereo continues to be the industry's medium of choice for the delivery of recorded music. This paper reviews some of the more notable multichannel efforts of the past that may finally lead toward new audio formats in the digital era.
"When I sit in an acoustically perfect hall (full of people), in the best seat for hearing, and listen to an orchestra, I hear such and such sounds. I want to hear precisely this effect from a recording, if that be possible."--An anonymous music critic ("K. K.") writing in the 1928 July issue of The Gramophone. "Through records, radio and television we are witnessing the greatest mass presentation of musical experience so far known to man."--Conductor Leopold Stokowski speaking at the 16th Convention of the Audio Engineering Society, 1964 October 14.
Although nearly 70 years have passed since "K. K." expressed his hope and more than 30 years since Stokowski reminded the audio engineering community of its responsibilities, the achievement of near-perfect fidelity remains to this day an elusive goal. With every subsequent improvement in the electrical fidelity of a recorded or transmitted sound signal, some progress has been made, but "K. K." specifically referred to the effect of what he heard. Today we understand that to be a psychophysical concern and largely a function of multichannel sound reproduction, a topic that was first addressed more than 100 years ago, and which to this day presents business audio industry.
and technical
challenges
* Manuscript received 1997 December 10. J.AudioEng.Soc.,Vol.46,No.1/2,1998January/February
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I THE EARLY YEARS Four years after Thomas Alva Edison filed his famous patent application for an "Improvement in Phonograph or Speaking Machines," a demonstration of a binaural transmission system was presented at La Lumi_re t_lectrique, the Electrical Exhibition held at the Paris Grand Opera in 1881. Designed by Clement Ader, the system employed four pairs of microphones connected to binaural telephone receivers in four remote listening rooms at the opera house. The eight pickup microphones were mounted at the front of the main stage, where singers and an orchestra performed nightly between 8 and 11 o'clock. Although the distance between the microphones of any one pair was only about a meter, one listener observed that "in listening with both ears at the two telephones, the sound takes a special character of relief and localization which a single receiver cannot produce. ''_ (See Fig. 1.) Ten years later, in the United States, the American Telephone and Telegraph Company (the "Long Distance Company") also conducted experiments with "telephone concerts" between Newton, Massachusetts, and New York City. A 1891 account in Scientific American 2 observed that "it has been found desireable to have a sepa- , rate transmitter [microphone] for each instrument . . . If
_Scientific American (1881 Dec. 3), reprinted in J. Audio Eng. Soc., vol. 29, pp. 368-372 (1981 May) and the JAES anthology Stereophonic Techniques. 2 "Long Distance Telephone Concerts," Scientific American (1891 Feb. 28). 27
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one transmitter is arranged to transmit music emanating from 50 instruments it must be so adjusted that the average result will be fair. Under these conditions the lighter violin parts are heard but very indistinctly, while the heavier parts produce very great noise, but the purity of the sound is affected. This, of course, gives very unsatisfactory results .... At the receiving station, when it is desired to fill halls of considerable size, as many as six loud-speaking receivers are used... These are distributed about the hall, being usually attached to the chandeliers." Unfortunately for those would-be early multichannel-sound enthusiasts, the telephone company engineers wired the transmitting microphones in series and connected them to a single long-distance line. Regardless of how many loudspeakers were hung from the light fixtures at the remote location, it was still only monophonic sound, Years later the telephone company finally did demonstrate long-distance multichannel-soundtransmission, in collaboration with conductor Leopold Stokowski. Stokowski, who was to become an honorary member of the AES and a convention speaker (see Fig. 2), was an early
sound."3 It was rumored at the time that during preparations for the demonstration "Stoky," as his musicians called him, kept turning the levels up as high as he could, requiring Bell Labs engineers to modify the reproducing equipment to keep him from overloading or destroying it. This was not to be Stokowski's only collaboration with Fletcher and other Bell Labs scientists. In 1936, for an outdoor concert at the Hollywood Bowl, he "insisted," according to one writer, that Fletcher (with Kenneth Morgan) be hired to install a three-channel soundreinforcement system there--presumably the first of its kind, but certainly not the last.
champion of multichannel sound and can be considered the first stereo control-board operator. In 1933, Harvey Fletcher and his coworkers at Bell Laboratories presenteda three-channel demonstration whichtransmitted
3 F. K. Becker, "A Compatible Stereophonic Sound System," Bell Lab. Rec. (1959 Nov.).
2 CINEMA LEADS THE WAY A major milestone in multichannel sound technology was reached in 1940 when Disney Studios released Fantasia, a film featuring musical selections conducted by Stokowski that were accompanied by imaginative images conceived at Disney. The film employed a new "Fantasound" process developed by W. E. Garrity and
three microphone signals of the sound of the Philadelphia Orchestra playing at the Academy of Music in Philadelphia to three corresponding loudspeakers on the stage at Constitution Hall in Washington. Stokowski chose not to conduct his orchestra on this occasion, leaving the task to his assistant Alexander Smallens, while he operated audio-level-controlling equipment from a director's box at the rear of the auditorium in Washington. The event created quite an excitement among those who listened to the reproduced concert. Some felt that the new system promised even greater emotional appeal than live music, but cooler heads attributed their reaction to the "enhanced volume range of the reproduced
Fig. 2. AES honorary members Emil Torick and Leopold Stokowski at 16th Convention of the Audio Engineering Society at New York's Barbizon Hotel Theater, 1964 October.
Fig. 1. Exhibition telephone room where visitors heard binaural transmission of Paris Opera (La Lumiere Electrique, 1881). 28
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J. N. A. Hawkins at the Disney Hyperion studios. 4 Early experiments with Fantasound used three widely separated horn loudspeakers at the front of the stage and two additional horns at the rear corners of the auditorium,
records and also the advent of magnetic tape recording. But in the mid 1950s engineers in England at Decca and at its German associate, Teldec, were studying the relative merits of vertical/lateral modulations on a disk
Two audio tracks were recorded optically, one feeding the center-front horn and the other track being used to feed the remaining four horns selectively. By the manual manipulation of the first constant-power pan pot, which had just been designed for this purpose, it was possible to move the apparent source of sound smoothly around the theater. After initial testing of this preliminary system, it was decided to add three more horns, one on each sidewall about halfway back from the stage and one on the ceiling at the center of the theater. This second version used three program tracks, one still dedicated to the center-front horn and the other two tracks being manually manipulated during playback to the remaining seven. It was intended that a mixer technician would provide the manual control of playback level and acoustic perspective during all road-show performances of the film, but this was soon deemed impractical, because it was too complicated for one person to manage, and it would have been nearly impossible to keep all showings alike. The playback technician was soon replaced by new technology in the development of what Garrity and Hawkins called the "brain" of the Fantasound reproducing equipment--a tone-operated gain-adjusting device they abbreviated "Togad." After several more improvements to the sound system, Fantasia received its world premiere showing at the Broadway Theater in New York in 1940. For that performance the sound system had been
versus the Blumlein method. By the time C. C. Davis and J. G. Frayne demonstrated the Westrex stereo record cutting head at the AES Convention in 1957 October, Blumlein's 45°/45 ° modulation technique had prevailed, and soon afterward stereo was the standard medium for all commercial recordings. The broadcasting industry soon followed suit, when in 1961 the FCC authorized FM stereo broadcasting, adopting technical standards based on the invention of Carl Eilers of Zenith while rejecting another, perhaps equally viable, by Murray Crosby. (Eiler's technology was also adopted later for use in stereo for television in the United States.) AM stereo broadcasting was also given consideration--at least twice. Five AM stereo systems were proposed to the FCC in the same docket that considered standards for FM stereo, but it declined to accept any, preferring not: to give the fledgling FM service, either mono or stereo, any additional competition from AM radio. Another industry attempt to establish AM stereo broadcasting occurred in 1978 with the submission to the FCC of the final test report of the National AM Stereophonic Radio Committee. The NAMSRC was unable to recommend a specific system, and neither was the FCC. It decided to leave the matter to a marketplace decision. The marketplace apparently has decided not to have stereo in AM radio. ·'
simplified to three stage horns, three program tracks, and a three-tone control track. During the first year Fantasound equipment was also installed at the Cathay Circle Theater in Los Angeles, where it provided automatic switching or panning of the left- and right-front signals to two rear horns at several times during the picture showing. (See Fig. 3.)
4 QUADRAPHONIC
3 STEREO COMES OF AGE It has been said that the history of audio can be divided into two periods: before Blumlein and after Blumlein. Certainly, the issuance of the 1933 patent 5 of the British engineer Alan Dower Blumlein was a landmark event, matrix, the single-groove 450/45 ° stereo record, and stereo broadcasting possibilities simultaneous anticipating, as it did, the sumbyand difference amplistereo tude and frequency modulation of a single radio-frequency carrier. Although Blumlein's patent was issued in 1933, use the until technology he taught be put the to practical more than 20 yearswould later. not Certainly demands of World War II on the efforts of scientists and
CACOPHONY
In 1968, a young professional bassoon player with more than just a passing interest in audio set the audio engineering community on a course that was to consume nearly all of its energies during the following decade. It was to ignite more impassioned industry battles in the marketplace and in technical standards committees than even the earlier controversies over cylindrical versus flat
2,298,618 _ /
J. Audio Eng. Soc., Vol. 46, No. 1/2, 1998 Januanj/FebmanJ
/'/?
H'__[ _ /./_ _____= _/_-__,_
/_/_ _/3
_y/______
engineers created a distraction, as did the postwar conversion from 78-r/min shellac records to 331/3-r/min vinyl
Soc. Motion Picture Eng. (1941 4 W. E. Garrity and j. N. A. Aug.). Hawkins, ,,Fantasound,,, j. 5 A. D. Blumlein, "British Patent Specification 394,325," ·reprinted in J. Audio Eng. Soc., vol. 6,:p. 91 (1958 Apr.) and in the JAES anthology Stereophonic Techniques.
Oct. 13, 1942. -
/44zz/,4/wE.. GAR/z,' do/_,v ,4/,4./-/,_w/c//vs INVENT©R,5'
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' · Fig. 3. Drawing from Garrity and Hawkin's patent 2,298,618, issued 1942 October 13. 29
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disk records or the famous "war of the speeds," which pitted advocates of 45-r/min disks against those who favored the 331/3-r/min speed, Peter Scheiber, that bassoonist, was not the first to suggest that four-channel audio might be a good idea. A few years earlier, record producers Joanna Nickrenz and Marc Aubort began marketing four-track tape recordings, and David Haffier, a violinist turned engineer, designed a matrix circuit which steered the out-of-phase components of a stereo signal to a pair of rear loudspeakers. But Scheiber went a major step further. He showed that four analog channels could be compressed into two and usefully restored to four (a 4-2-4 matrix) if wideband phase-shift networks were employed in the encodlng and decoding processes. If the channel separation of the recovered signals might be as little as 3 dB for some intended locations in the listening space, a switchlng-type decoder could be used to increase the apparent audible separation, as the Disney "Togad" had done nearly 30 years earlier, Scheiber's first demonstrations to the industry generally received a lukewarm reception, but the one given to CBS executives caught the attention of Benjamin B. Bauer. Backed by the resources of CBS Laboratories and the CBS Records Group, Bauer became an instant convert to the virtues of surround sound and of quadraphony in particular. Rejecting the specific phase and amplitude parameters of the Scheiber matrix, Bauer developed his own matrix, which he called SQ (for stereo-quad) and for which he claimed superior spatial attributes and compatibility in stereo or monophonic playback. With boundless energy, which earned him the nickname "Quad Father" by his colleagues at CBS, he set out to convince the world of the virtues of the SQ system. (See Fig. 4.) Bauer did not have the field to himself for very long. Soon there was a QS matrix from the Sansui Corporation, QMX from University of Illinois professor Duane
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Cooper (supported by Nippon Columbia), and Ambisonics from Michael Gerzon in the United Kingdom. And one day it was no longer simply a question of which matrix might be superior but whether recordings of the future would be based on a matrix or a "discrete" format. The battle lines to this latter question were drawn when the JVC Corporation and RCA Records introduced the CD-4 record, developed by JVC engineer Toshiya Inoue, which incorporated 30-kHz suppressed-carrier modulations on the sidewalls of the record grooves.6 Even before the advent of CD-4 records, a young engineer in California, Louis Dorren, had become a convert to quadraphony and invented an improvement to the standard FM stereo radio transmission signal which claimed fully discrete four-channel reception. Like Bauer's, Dorren's work attracted the attention of others, and when the Electronic Industries Association (EIA) established its National Quadraphonic Radio Committee (NQRC) in 1972, it had entries from Dorren's Quadracast Co., RCA, Cooper-Nippon Columbia, General Electric, Zenith, and CBS, the latter advocating only the use of the SQ matrix for the baseband stereo signal, while all the others employed various subcarrier configurations. The NQRC sent its massive final test report 7 to the U.S. FCC at the end of 1975, hoping to gain prompt modification of the broadcast rules and regulations to establish transmission standards for quadraphonic broadcasting. But the topic languished at the FCC for a decade without action by the regulators. When a decision was finally made, it was simply to permit the use of additional subcarriers in FM broadcasting for any purpose a broadcaster desired. 6 Numerous papers describing the technical specifications of the variouscompetingquadraphonicsystemsare reprinted in the JAES anthology Quadraphony. 7 "Report of the National Quadraphonic Radio Committee to the Federal Communications Commission" (Electronic Industries Association, 1975 Nov.).
Fig. 4. Benjamin B. Bauer describes the operation of his quadraphonic system at the Festival de Musique, Montreux-Vevey, in 1974. 30
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But the allure of quadraphony had diminished long before the FCC's action on the subject. Writers at the time speculated on possible reasons. Some thought that even the most creative recording producers were never able to fully exploit the new medium, which locked them into rigid four-corner reproduction. Others pointed out that competing interests seemed to spend more time denigrating their competition than touting their own systerns, creating a hopelessly confused marketplace which offered potential consumers little incentive for support, Some even Concluded that four loudspeakers in one room created just too much clutter for the average household. All of the above may be true and partly responsible for the ill fate of quadraphony, but one additional factor seems to have been neglected. The CBS experience provides a good illustration of what may have really happened. When CBS introduced SQ records, it recognized that there would be a significant increase in postproduction mixing costs for four-channel programs. Consequently, SQ records carried a suggested retail price of $7.00 each, in contrast with the $6.00 price for regular stereo records. It seemed like a good idea at the time, and sales figures for the new disks exhibited ever-increasing growth curves. However, as the number of new SQ releases grew, dissenting voices were heard from retail dealers, who vigorously objected to their need to maintain shelf space for dual inventories (actually more than dual, counting magnetic-tape products). CBS responded to these criticisms by announcing that they would release each future program in only one format, regular stereo or stereo-compatible SQ. Furthermore, since it was recognized that most consumers were still purchasing records only for stereo playback, prices for SQ records would be reduced to the stereo price. When this policy was instituted, it was no longer possible for CBS Records to determine which portion of sales was for quad:aphonic playback, and there seemed to be no increase in overall sales, only an increase in production costs for the four-channel product. It soon quietly discontinued its efforts in quadraphony, and other companies, if they had not already done so, followed suit. The quadraphonic era had ended--because the recording industry could not create a profitable business in it. 5 RECENT EVENTS While the generals in the quadraphonic busily engaged in their quest for dominance
war were in the re-
cording and broadcast industries. Dolby Laboratories was quietly modifying parameters of the 4-2-4 matrix for an application that seems to have been unnoticed by
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others--surround sound for the cinema:Instead of fourcorner quadraphony, Dolby reaffirmed the importance of center-front sound (particularly for dialogue) and used the remaining three channels for left, right, and surround effects. Although the film industry readily embraced the Dolby matrix, the television industry did not, except for the occasional broadcast of a film already employing a matrixed sound track. Nor did the television industry accept a proposed discrete triphonic system, s apparently because it, too, would have resulted in significant additional production costs. Now the era of digital sound recording and transmission has begun. It is much too soon to provide a historical perspective on the various advanced audio systems that are being proposed, but at the present time, if there is general agreement on any one matter, it is that the mini: mum specification for the entertainment sound track of the future should be at least that which the Fantasound system offered nearly 60 years ago, namely, three channels in the front and two channels for the surround. The film industry is already embarked on such a course, but under competing technologies. In the television industry, standards-setting bodies for advanced digital service have agreed to follow the cinema approach, but only time will tell if broadcasters will be willing to bear the additional expense of multichannel productions. In radio, new digital broadcast systems are now being tested and will probably be able to utilize any new program format that the record industry might offer in the future. Will the recording industry ever offer multichannel sound? The answer is not clear. The compact disc has been a resounding commercial success because the cost to the consumer of converting from vinyl record reproduction is low, and because it has offered the recording industry an opportunity to rerelease programs from its libraries with little or no additional editing expense. A future multichannel format in the recording industry will require at least two mixes for each production--a multichannel mix and a stereo mix, since recent studies seem to indicate that simple electrical compatibility among various playback modes does not guarantee artistic cornpatibility. Will the recording industry find a way to fash-' ion a profitable business in multichannel sound, or will it reach the same conclusion as it did for quadraphony? If it can succeed this 6me, it will be a tribute to the audio engineering community for all its efforts in advancing this technology. s E. Torick, "A Triphonic Sound System for Television Broadcasting," J. Soc. Motion Picture Telev. Eng., vol. 92 (1983 Aug.).
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