Sensurround
Encyclopedia
Sensurround is the trademark name for a process developed in the 1970s by Cerwin-Vega in conjunction with Universal Studios
to enhance the audio experience during film screenings. Specifically developed for the 1974 film Earthquake, the process was intended for subsequent use and was adopted for three more films, Midway (1976), Rollercoaster (1977) and in the theatrical version of Saga of a Star World
(1978), the Battlestar Galactica
pilot. Sensurround worked by adding extended-range bass for sound effect
s. The low-frequency sounds were more felt than heard, providing a vivid complement to onscreen depictions of earth tremors, bomber formations, and amusement park rides. The overall trend toward "multiplex" cinema structures presented challenges that made Sensurround impractical as a permanent feature of cinema.
Sensurround helped bring wider recognition to established loudspeaker
manufacturer Cerwin Vega, and aided in establishing a strong reputation for new audio amplifier
company BGW Systems
. The increased awareness of extended low-frequency sound reproduction that Sensurround brought to film audiences was a factor in the increase in subwoofer
sales and in the rise in the number of subwoofer designs in the late 1970s and 1980s.
The original Sensurround design used for "Earthquake" employed a pseudorandom noise generator
, designed by D. Broadus "Don" Keele, Jr., to create the low-frequency rumble, with the waveform matching that of the 1971 Sylmar earthquake
. Two low frequency control tones were printed on the film's mono optical or magnetic track; from the projector, the tones entered a control box in the projection booth, which fed low frequency pseudorandom noise to 1,600 watt BGW 750 audio amplifiers driving the speakers. The control box generated a pseudorandom noise signal with energy between 17 and 120 Hz. The control track method was employed because there was no way to accurately record bass lower than 40 Hz on an optical or magnetic film soundtrack at the time. When receiving the noise signal, the amplifier and subwoofers responded with sound pressures ranging from 110 dB at the center of the theater to a maximum of 120 dB measured 4 feet in front of any horn. The resulting rumble could be felt by audience members as well as heard.
For the film Earthquake, Sensurround was activated during the quake scenes to augment the conventional soundtrack. In addition, portions of the main soundtrack were redirected to the Sensurround horns to create a partial surround sound
effect. The control tones recorded on the film's optical or magnetic track triggered the rumble or surround sound effects as well as controlling their volume and the overall blend of the main soundtrack and low frequency noise effects. Two tones of 25 Hz and 35 Hz were used: these two tones allowed different effects to be activated when desired: the rumble could be turned on or off in the Sensurround horns, the main soundtrack could be sent to the Sensurround horns, the level of both the rumble and the soundtrack coming from the horns could be varied by varying the level of the control tones and the theater's main audio system could be increased in level by up to 8 dB at select points to create a greater dynamic range (MCA called this the "Step-Gain" function.)
For the original version of Sensurround, prints were available in the following formats:
was incorporated to increase the dynamic range and reduce audible noise created by the optical process. MCA also changed the way the control tones were used, allowing the Sensurround horns in the front and back of the theater to be controlled independently. This allowed for more creative effects, such as a sound being panned from front to back of the theater. Re-engineering the system was important to MCA because there were times during dialogue sequences when the sound mixers wanted the Sensurround running but didn't want the dialogue to shift to the back of the theater. Having separate control of the front and back groups of Sensurround horns allowed this. The drivers in the Sensurround horns were improved to extend their frequency response higher so they could reproduce the low notes in music, thus allowing sound mixers to incorporate music into the Sensurround system (this was used to good effect in Rollercoaster.) Advancements by RCA in optical soundtrack recording led MCA engineers to the realization that an optical track could reliably record and reproduce bass down to 10 Hz. As well, removal of the Academy equalization would allow the high frequency response to be extended upward by an additional octave. The addition of dbx Type-II noise reduction and its attendant increase in useful dynamic range created a high-fidelity sound from a conventional optical print. MCA called this re-engineering of the system 'Sensurround Mod-II' and the 'public' name of the system was changed from just 'Sensurround' to the 'Sensurround Special Effects System.'
Unlike the original version of Sensurround, Mod-II (and later, Mod-III) were only for use with mono optical soundtracks. Due to the use of dbx Type-II noise reduction, MCA eliminated the standard Academy Filter traditionally used on optical prints, thus giving Sensurround an increased frequency response of 16 Hz to 16 kHz and a dynamic range of 86 dB, superior to 70mm magnetic prints of the time. It also allowed a mono optical track to have surround sound effects and MCA began to market the system to other studios and producers as a truly high-fidelity sound and special effects system. Dolby Stereo
optical was just beginning to become known in the industry and MCA felt they had a viable competing format. While Warner Bros and Paramount seriously considered adopting the system, in the end only Universal Studios ever released films using the process. Both Warner and Paramount later patented their own "special effects" systems to create Sensurround-type effects.
Sensurround was a highly successful theatrical sound system. By 1976, when Midway opened, there were over 800 theaters with Sensurround capability in the USA. Worldwide, there were over 2000 Sensurround theaters. During the initial design of the system MCA figured it would be installed in a limited number of theaters across the USA—perhaps 30 in all—and that smaller theaters, or theaters in small towns, wouldn't want to bother with the installation or the loss of seating capacity necessitated by the large Sensurround horns. This was quickly disproved: Earthquake premiered with 17 Sensurround installations and by the end of its run over 400 theaters had shown the film in Sensurround. Midway opened with 300 Sensurround-equipped theaters. At first, MCA only rented Sensurround to theaters at a cost of $500 per week, but by the opening of Midway, theaters could purchase the systems outright and MCA had begun to ship the Model-M horns to theaters un-assembled. Theater owners also had the option of purchasing only the Cerwin-Vega drivers and horn cabinet blueprints, buying the wood and making the horn cabinets themselves. MCA made these changes due to the success of the system and because the shipping costs of the heavy Sensurround horns were becoming very expensive.
Throughout the history of the Sensurround program, RCA Technical Services performed the theater installations and maintenance. If repairs or replacements were required, the RCA technicians contacted MCA Systems to order needed parts. Because control tones were used to trigger the Sensurround horns, theaters could not generally use the system with their standard films unless a rewiring was done.
for "the development and engineering of the Sensurround System for motion picture presentation." The film Earthquake also won an Academy Award for Best Sound
(Ronald Pierce
, Melvin M. Metcalfe Sr.).
In 1976, MCA was granted for the Sensurround system.
Sensurround made Earthquake a popular "event" film in 1974 and one of the year's highest-grossing films. Sensurround presented practical challenges, though, in multiplex cinemas
where separate theater spaces shared walls. Audiences for The Godfather, Part II, which opened the same month (November 1974) as Earthquake, often complained to theater managers about the Sensurround effect when Earthquake was shown in an adjoining theater. The low-frequency vibrations rattled tiles and plaster, too, leading to damage in some venues. A safety net was installed at Mann's Chinese Theatre
in Hollywood to catch errant pieces of plaster falling from the ceiling. When Earthquake was screened in Chicago, the head of the Chicago Building and Safety Department demanded that the system be turned down or removed to prevent damage to city theaters. In Germany Sensurround movies could only be screened in single-screen houses. Subsequent Sensurround films, such as Midway, also tended to play in single-screen cinemas.
The success of Star Wars
over Rollercoaster in the summer 1977 demonstrated to theater operators the limits of Sensurround as a guarantor of audience draw. Saga of a Star World
(aka: Battlestar Galactica) marked the final bow of Sensurround one year later (1978).
released Damnation Alley
(1977) in Sound 360
, and Warner Brothers employed their Megasound
process for Altered States
(1980), Outland
(1981), Wolfen
(1981) and Superman II
(1981).
The DVD of Earthquake from Universal Home Video, released on May 9, 2006, claims to feature the Sensurround track (described as "Sensurround 3.1" but not related to "Sensurround Mod-III"). In this case, the Sensurround 3.1 track is just the mono soundtrack fed to the 3 front speakers and the LFE channel. The 25 and 35 Hz control tones are present on the LFE track even though original audiences never heard these tones. The 3.1 sound mix is not a duplication of the Sensurround system, and neither is the 5.1 soundtrack. The 5.1 channel Dolby Digital mix is a completely new remix of the 4-track stereo original and in no way duplicates or even simulates the original Sensurround experience, nor does it convey the quality of the original 4-track mix. Earthquake was one of the first 4-track mag films to be mixed with all dialog confined to the center channel
; directional dialogue was not used. For theaters that did not install the Sensurround system, the original mix utilized extensive surround effects. Mag stereo prints used the 12 kHz CinemaScope
'switching' tone included on the surround track to reduce hiss heard from the surround speakers. (The 12 kHz switching was a gating
technique used as a crude method of noise reduction
and was employed from the beginning of the CinemaScope format.) In theaters that utilized Sensurround and the magnetic stereo prints of Earthquake, the No. 4 (surround) magnetic preamplifier was disconnected and the print's surround track was not used at all. For both mono and mag stereo prints, the Sensurround system itself provided the surround sound effects by feeding the center channel (mag track #2) to the Sensurround horns in the back of the theater. None of the surround channel effects are present in the surround loudspeakers on the 5.1 channel DVD mix of Earthquake—they are all mixed to the front channels.
Furthermore, the DVDs of Battlestar Galactica, Midway and Rollercoaster aren't authentic as the 'rumble' on their tracks is that of the control tones. Because they had no control over the sound system equipment used by home viewers, no attempt was made by Universal to properly reproduce the surround sound effect that was such an integral part of the Sensurround experience.
. They are loaned on occasion for revival screenings of films using the process. At least one replica system exists, as it was custom built for a 2004 London revival screening of Earthquake. Sensurround Mod-II and Mod-III boxes are extremely common and relatively easy to find from old theater equipment dealers and can be bought for $50 or so. The Mod-II and Mod-III boxes were mostly just modifications of the original control boxes, but the changes are not easily undone to make them capable of running "Earthquake" because MCA did all the modifications themselves and never released any documentation about the changes made to each circuit card in the unit.
released a song entitled "Sensurround" that was incorporated in the soundtrack to Mighty Morphin Power Rangers: The Movie
and (in a different, faster-paced recording) their EP
S-E-X-X-Y
. The song makes several references to the innovation, especially as used in Earthquake.
An early FoxTrot comic has Jason presenting his dinosuar movie in Sensurround.
Universal Studios
Universal Pictures , a subsidiary of NBCUniversal, is one of the six major movie studios....
to enhance the audio experience during film screenings. Specifically developed for the 1974 film Earthquake, the process was intended for subsequent use and was adopted for three more films, Midway (1976), Rollercoaster (1977) and in the theatrical version of Saga of a Star World
Saga of a Star World
"Saga of a Star World" is the pilot for the American science fiction television series of Battlestar Galactica which was produced in 1978 by Glen A. Larson...
(1978), the Battlestar Galactica
Battlestar Galactica
Battlestar Galactica is an American science fiction franchise created by Glen A. Larson. The franchise began with the Battlestar Galactica TV series in 1978, and was followed by a brief sequel TV series in 1980, a line of book adaptations, original novels, comic books, a board game, and video games...
pilot. Sensurround worked by adding extended-range bass for sound effect
Sound effect
For the album by The Jam, see Sound Affects.Sound effects or audio effects are artificially created or enhanced sounds, or sound processes used to emphasize artistic or other content of films, television shows, live performance, animation, video games, music, or other media...
s. The low-frequency sounds were more felt than heard, providing a vivid complement to onscreen depictions of earth tremors, bomber formations, and amusement park rides. The overall trend toward "multiplex" cinema structures presented challenges that made Sensurround impractical as a permanent feature of cinema.
Sensurround helped bring wider recognition to established loudspeaker
Loudspeaker
A loudspeaker is an electroacoustic transducer that produces sound in response to an electrical audio signal input. Non-electrical loudspeakers were developed as accessories to telephone systems, but electronic amplification by vacuum tube made loudspeakers more generally useful...
manufacturer Cerwin Vega, and aided in establishing a strong reputation for new audio amplifier
Audio amplifier
An audio amplifier is an electronic amplifier that amplifies low-power audio signals to a level suitable for driving loudspeakers and is the final stage in a typical audio playback chain.The preceding stages in such a chain are low power audio amplifiers which perform tasks like pre-amplification,...
company BGW Systems
BGW Systems
BGW Systems is a designer and manufacturer of audio power amplifiers based in Southern California in the United States. The company also manufactures other audio electronics designs as well as computer systems and sheet metal products.-History:...
. The increased awareness of extended low-frequency sound reproduction that Sensurround brought to film audiences was a factor in the increase in subwoofer
Subwoofer
A subwoofer is a woofer, or a complete loudspeaker, which is dedicated to the reproduction of low-pitched audio frequencies known as the "bass". The typical frequency range for a subwoofer is about 20–200 Hz for consumer products, below 100 Hz for professional live sound, and below...
sales and in the rise in the number of subwoofer designs in the late 1970s and 1980s.
Original design
Sensurround involved the installation of large, low frequency, horn-loaded speakers which contained specially designed 18-inch Cerwin-Vega Model 189 E drivers in custom black wood cabinets. Three horn configurations were available, Model-C (Corner), Model-W (Folded Bass Bin) and Model-M (Modular). The Model-C and -M horns required stacking in groups of four, increasing effective horn mouth size to achieve the low frequency target. They came with special extenders used to widen the mouths of the horns and take advantage of the theater walls to further increase low frequency extension. The Model-M horn had a dedicated "Mouth-Extender" available when it was used in the front of the theater. While installation was customized and varied in each theater, the Sensurround horns were typically placed beneath the screen in front and in the back corners of the theater. Often, rows or sections of seats would have to be removed to make room for the large Sensurround horns. In large theaters, up to 20 individual horns might be used along with custom-built bat wings and mouth extenders.The original Sensurround design used for "Earthquake" employed a pseudorandom noise generator
Pseudorandom number generator
A pseudorandom number generator , also known as a deterministic random bit generator , is an algorithm for generating a sequence of numbers that approximates the properties of random numbers...
, designed by D. Broadus "Don" Keele, Jr., to create the low-frequency rumble, with the waveform matching that of the 1971 Sylmar earthquake
Sylmar earthquake
The 1971 San Fernando earthquake struck the San Fernando Valley near Sylmar, California at 6:00:55 a.m. PST on February 9, 1971, with a magnitude of 6.6....
. Two low frequency control tones were printed on the film's mono optical or magnetic track; from the projector, the tones entered a control box in the projection booth, which fed low frequency pseudorandom noise to 1,600 watt BGW 750 audio amplifiers driving the speakers. The control box generated a pseudorandom noise signal with energy between 17 and 120 Hz. The control track method was employed because there was no way to accurately record bass lower than 40 Hz on an optical or magnetic film soundtrack at the time. When receiving the noise signal, the amplifier and subwoofers responded with sound pressures ranging from 110 dB at the center of the theater to a maximum of 120 dB measured 4 feet in front of any horn. The resulting rumble could be felt by audience members as well as heard.
For the film Earthquake, Sensurround was activated during the quake scenes to augment the conventional soundtrack. In addition, portions of the main soundtrack were redirected to the Sensurround horns to create a partial surround sound
Surround sound
Surround sound encompasses a range of techniques such as for enriching the sound reproduction quality of an audio source with audio channels reproduced via additional, discrete speakers. Surround sound is characterized by a listener location or sweet spot where the audio effects work best, and...
effect. The control tones recorded on the film's optical or magnetic track triggered the rumble or surround sound effects as well as controlling their volume and the overall blend of the main soundtrack and low frequency noise effects. Two tones of 25 Hz and 35 Hz were used: these two tones allowed different effects to be activated when desired: the rumble could be turned on or off in the Sensurround horns, the main soundtrack could be sent to the Sensurround horns, the level of both the rumble and the soundtrack coming from the horns could be varied by varying the level of the control tones and the theater's main audio system could be increased in level by up to 8 dB at select points to create a greater dynamic range (MCA called this the "Step-Gain" function.)
For the original version of Sensurround, prints were available in the following formats:
- 35mm 4-Track Magnetic with Optical Track (magoptical): This type of Sensurround print was not usable as a mono optical print. Unlike standard magoptical prints, in which the optical track was a mono version of the magnetic stereo tracks, the optical track on magnetic Sensurround prints contained only the control tones. If played as a standard optical print, only the 25 Hz and 35 Hz control tones would be heard. To control the Sensurround System and its volume levels, control tones recorded on the optical track varied from −14 to −6 dB below 100% modulation and activation of the Sensurround System occurred at −16 dB. For program sounds applied to the Sensurround Horns, Track-2 (Center Front) was used, with its level and timing controlled by the 25 Hz control tone. For magnetic playback in mono, Track-2 (Center Front) could be used because Earthquake was mixed with mono dialogue, unlike most stereo films up to that time. For 4-Track equipped theaters that wanted to run "Earthquake" without Sensurround, the standard 12 kHz CinemaScope switching signal was recorded on Track-4 (surround). Because no noise reduction system was used on magnetic prints at the time, and due to the lower technical performance of the surround channels magnetic track, this switching system was implemented by 20th Century Fox during CinemaScope’s development to reduce the hiss and system noise heard from the surround speakers. For Earthquake’s run in the United States, the surround speakers were disconnected and the Sensurround system was relied upon to produce all the surround sound effects. Track-4 was not used at all – it wasn’t even connected to the Sensurround Integrator. However, in Europe, the surround track was used in the normal manner, being controlled by the Sensurround Integrator like the other magnetic channels. No reason for this difference has ever been found.
- 35mm Mono Optical: These were dual-purpose prints and could be used either with or without Sensurround. The optical track was a composite mix of the program and the control tones and were compatible with any optical playback system. All mono mixes of the Earthquake soundtrack contain the control tones. To control the Sensurround System and its volume levels, control tones recorded on the optical track varied from −28 dB to −20 dB below 100% modulation. Activation of the Sensurround System occurred at −30 dB. For program sounds applied to the Sensurround Horns, the composite mono soundtrack was used, with its volume and timing regulated by the 25 Hz control tone. Note: A mono optical Sensurround print was used for the MCA DiscoVision release of Earthquake in 1978. If you have a system with good low-frequency extension, you can hear the control tones at various points in the film. If you have a Sensurround Model-1 Integrator with its rumble generator you could even screen the film in Sensurround!
- 70mm 6-Track Magnetic Stereo: The Sensurround Control Tones were recorded on Tracks 2 and 4 and are 100 Hz instead of 25 Hz and 35 Hz. This was because the magnetic system couldn’t reproduce the very low-frequency control tones reliably. The 100 Hz tone on Track-2 controls the program effects applied to the Sensurround Horns and the 100 Hz tone on Track-4 controls the rumble effect applied to the Sensurround horns. Like the other systems, the level of the 100 Hz tones varies the levels applied to the Sensurround horns and when both control tones are present, the Step/Hi-Gain function is turned on to increase the dynamic range of the main program by 8dB. Track-3 (Center Front) is applied to the Sensurround system for program sounds. No other signal is recorded on Tracks 2 & 4. 70mm Sensurround prints were issued ONLY outside of the USA. In addition, Earthquake was the only Sensurround film recorded in stereo or issued with 70mm prints. All other Sensurround films were 35mm mono optical in the Sensurround Mod-II or Mod-III format.
Sensurround Mod-II
Even before Earthquake ended its theatrical run, MCA began a program to re-engineer the Sensurround system to enable the recording of the deep bass on a standard 35mm optical soundtrack, with no external rumble generator being required, as well as improve fidelity and the overall effect and to simplify the system. In addition, dbx Type-II noise reductionDbx (noise reduction)
dbx is a family of noise reduction systems developed by the company of the same name. The most common implementations are dbx Type I and dbx Type II for analog tape recording and, less commonly, vinyl LPs. A separate implementation, known as dbx-TV, is part of the MTS system used to provide stereo...
was incorporated to increase the dynamic range and reduce audible noise created by the optical process. MCA also changed the way the control tones were used, allowing the Sensurround horns in the front and back of the theater to be controlled independently. This allowed for more creative effects, such as a sound being panned from front to back of the theater. Re-engineering the system was important to MCA because there were times during dialogue sequences when the sound mixers wanted the Sensurround running but didn't want the dialogue to shift to the back of the theater. Having separate control of the front and back groups of Sensurround horns allowed this. The drivers in the Sensurround horns were improved to extend their frequency response higher so they could reproduce the low notes in music, thus allowing sound mixers to incorporate music into the Sensurround system (this was used to good effect in Rollercoaster.) Advancements by RCA in optical soundtrack recording led MCA engineers to the realization that an optical track could reliably record and reproduce bass down to 10 Hz. As well, removal of the Academy equalization would allow the high frequency response to be extended upward by an additional octave. The addition of dbx Type-II noise reduction and its attendant increase in useful dynamic range created a high-fidelity sound from a conventional optical print. MCA called this re-engineering of the system 'Sensurround Mod-II' and the 'public' name of the system was changed from just 'Sensurround' to the 'Sensurround Special Effects System.'
Unlike the original version of Sensurround, Mod-II (and later, Mod-III) were only for use with mono optical soundtracks. Due to the use of dbx Type-II noise reduction, MCA eliminated the standard Academy Filter traditionally used on optical prints, thus giving Sensurround an increased frequency response of 16 Hz to 16 kHz and a dynamic range of 86 dB, superior to 70mm magnetic prints of the time. It also allowed a mono optical track to have surround sound effects and MCA began to market the system to other studios and producers as a truly high-fidelity sound and special effects system. Dolby Stereo
Dolby Stereo
Dolby Stereo, is the trade mark that Dolby Laboratories used for the various analogue stereo cinema sound formats that they produced.Two basic systems used this name. The first was the 'Dolby SVA' system used with optical soundtracks on 35mm film...
optical was just beginning to become known in the industry and MCA felt they had a viable competing format. While Warner Bros and Paramount seriously considered adopting the system, in the end only Universal Studios ever released films using the process. Both Warner and Paramount later patented their own "special effects" systems to create Sensurround-type effects.
Sensurround Mod-III
Mod-III Sensurround was a further refinement of the system to allow more control over level, timbre and placement of effects. Instead of a simple wide-range rumble that could be felt and heard, Mod-III used more narrow band extended low frequency effects in the 16–25 Hz range, in addition to the higher frequency program sounds and surround-sound effect. Thus, scenes could have dialogue and other audio at standard levels, plus the effect of movement from the infrasonic rumble, creating sensations that had not been possible in earlier Sensurround films. Mod-III Sensurround was used in Battlestar Galactica in 1978.Sensurround was a highly successful theatrical sound system. By 1976, when Midway opened, there were over 800 theaters with Sensurround capability in the USA. Worldwide, there were over 2000 Sensurround theaters. During the initial design of the system MCA figured it would be installed in a limited number of theaters across the USA—perhaps 30 in all—and that smaller theaters, or theaters in small towns, wouldn't want to bother with the installation or the loss of seating capacity necessitated by the large Sensurround horns. This was quickly disproved: Earthquake premiered with 17 Sensurround installations and by the end of its run over 400 theaters had shown the film in Sensurround. Midway opened with 300 Sensurround-equipped theaters. At first, MCA only rented Sensurround to theaters at a cost of $500 per week, but by the opening of Midway, theaters could purchase the systems outright and MCA had begun to ship the Model-M horns to theaters un-assembled. Theater owners also had the option of purchasing only the Cerwin-Vega drivers and horn cabinet blueprints, buying the wood and making the horn cabinets themselves. MCA made these changes due to the success of the system and because the shipping costs of the heavy Sensurround horns were becoming very expensive.
Throughout the history of the Sensurround program, RCA Technical Services performed the theater installations and maintenance. If repairs or replacements were required, the RCA technicians contacted MCA Systems to order needed parts. Because control tones were used to trigger the Sensurround horns, theaters could not generally use the system with their standard films unless a rewiring was done.
Awards
In 1974, Waldon O. Watson, Richard J. Stumpf, Robert J. Leonard and the Universal City Studios Sound Department received a special Scientific and Engineering Academy AwardAcademy Award, Scientific or Technical
Since 1931, the Academy of Motion Picture Arts and Sciences has given the Scientific and Technical Award, an Academy Award for scientific or technical achievements, which are presented at "a dinner ceremony separate from the annual telecast."...
for "the development and engineering of the Sensurround System for motion picture presentation." The film Earthquake also won an Academy Award for Best Sound
Academy Award for Sound
The Academy Award for Sound Mixing is an Academy Award that recognizes the finest or most euphonic sound mixing or recording, and is generally awarded to the production sound mixers and re-recording mixers of the winning film. Compare this award to the Academy Award for Sound Editing...
(Ronald Pierce
Ronald Pierce (sound engineer)
Ronald Pierce was an American sound engineer. He won an Academy Award for Best Sound and was nominated for two more in the same category.-Selected filmography:Pierce won an Academy Award and was nominated for two more:Won* Earthquake Nominated...
, Melvin M. Metcalfe Sr.).
In 1976, MCA was granted for the Sensurround system.
Drawbacks
Sensurround speakers involved expense for theater owners. Rental for speakers cost $500 a month in 1974 and their installation involved the removal of some seats. The extra expense was commercially justifiable as long as it appeared to provide an advantage in drawing audiences.Sensurround made Earthquake a popular "event" film in 1974 and one of the year's highest-grossing films. Sensurround presented practical challenges, though, in multiplex cinemas
Movie theater
A movie theater, cinema, movie house, picture theater, film theater is a venue, usually a building, for viewing motion pictures ....
where separate theater spaces shared walls. Audiences for The Godfather, Part II, which opened the same month (November 1974) as Earthquake, often complained to theater managers about the Sensurround effect when Earthquake was shown in an adjoining theater. The low-frequency vibrations rattled tiles and plaster, too, leading to damage in some venues. A safety net was installed at Mann's Chinese Theatre
Grauman's Chinese Theatre
Grauman's Chinese Theatre is a movie theater at 6925 Hollywood Boulevard in Hollywood. It is on the historic Hollywood Walk of Fame.The Chinese Theatre was commissioned following the success of the nearby Grauman's Egyptian Theatre which opened in 1922...
in Hollywood to catch errant pieces of plaster falling from the ceiling. When Earthquake was screened in Chicago, the head of the Chicago Building and Safety Department demanded that the system be turned down or removed to prevent damage to city theaters. In Germany Sensurround movies could only be screened in single-screen houses. Subsequent Sensurround films, such as Midway, also tended to play in single-screen cinemas.
The success of Star Wars
Star Wars
Star Wars is an American epic space opera film series created by George Lucas. The first film in the series was originally released on May 25, 1977, under the title Star Wars, by 20th Century Fox, and became a worldwide pop culture phenomenon, followed by two sequels, released at three-year...
over Rollercoaster in the summer 1977 demonstrated to theater operators the limits of Sensurround as a guarantor of audience draw. Saga of a Star World
Saga of a Star World
"Saga of a Star World" is the pilot for the American science fiction television series of Battlestar Galactica which was produced in 1978 by Glen A. Larson...
(aka: Battlestar Galactica) marked the final bow of Sensurround one year later (1978).
Competing Processes
The success of Sensurround as an effect led rival studios to develop their own audio enhancements. 20th Century Fox20th Century Fox
Twentieth Century Fox Film Corporation — also known as 20th Century Fox, or simply 20th or Fox — is one of the six major American film studios...
released Damnation Alley
Damnation Alley (film)
Damnation Alley is a 1977 film, directed by Jack Smight, loosely based on the novel of the same name by Roger Zelazny. The original music score was composed by Jerry Goldsmith.-Plot:...
(1977) in Sound 360
Sound 360
Sound 360 was the name of a motion picture sound system used by 20th Century-Fox to enhance the premiere engagements of their 1977 feature Damnation Alley....
, and Warner Brothers employed their Megasound
Megasound
Megasound was the name of a movie theater sound system created by Warner Bros. in the early 1980s. It was used to enhance the premiere engagements of a handful of Warner features, including Altered States , Outland, Wolfen and Superman II .Theaters equipped for Megasound had additional speakers...
process for Altered States
Altered States
Altered States is a 1980 American science fiction-horror film adaptation of a novel by the same name by playwright and screenwriter Paddy Chayefsky. It was the only novel that Chayefsky ever wrote, as well as his final film. Both the novel and the film are based on John C...
(1980), Outland
Outland (film)
Outland is a 1981 British science fiction thriller film written and directed by Peter Hyams.Set on Jupiter's moon Io, it has been described as a space Western, and bears thematic resemblances to High Noon....
(1981), Wolfen
Wolfen (film)
Wolfen is the title of a 1981 horror film starring Albert Finney, Diane Venora, Gregory Hines and Edward James Olmos based on Whitley Strieber's 1978 novel The Wolfen...
(1981) and Superman II
Superman II
Superman II is the 1980 sequel to the 1978 superhero film Superman and stars Gene Hackman, Christopher Reeve, Terence Stamp, Ned Beatty, Sarah Douglas, Margot Kidder, and Jack O'Halloran. It was the only Superman film to be filmed by two directors...
(1981).
Remastering
Releases for home video have attempted to reproduce the Sensurround effect in various ways.The DVD of Earthquake from Universal Home Video, released on May 9, 2006, claims to feature the Sensurround track (described as "Sensurround 3.1" but not related to "Sensurround Mod-III"). In this case, the Sensurround 3.1 track is just the mono soundtrack fed to the 3 front speakers and the LFE channel. The 25 and 35 Hz control tones are present on the LFE track even though original audiences never heard these tones. The 3.1 sound mix is not a duplication of the Sensurround system, and neither is the 5.1 soundtrack. The 5.1 channel Dolby Digital mix is a completely new remix of the 4-track stereo original and in no way duplicates or even simulates the original Sensurround experience, nor does it convey the quality of the original 4-track mix. Earthquake was one of the first 4-track mag films to be mixed with all dialog confined to the center channel
Center channel
Center channel refers to an audio channel common to many surround sound formats. It is the channel that is mostly, or fully, dedicated to the reproduction of the dialogue of an audiovisual program...
; directional dialogue was not used. For theaters that did not install the Sensurround system, the original mix utilized extensive surround effects. Mag stereo prints used the 12 kHz CinemaScope
CinemaScope
CinemaScope was an anamorphic lens series used for shooting wide screen movies from 1953 to 1967. Its creation in 1953, by the president of 20th Century-Fox, marked the beginning of the modern anamorphic format in both principal photography and movie projection.The anamorphic lenses theoretically...
'switching' tone included on the surround track to reduce hiss heard from the surround speakers. (The 12 kHz switching was a gating
Noise gate
A Noise Gate or gate is an electronic device or software that is used to control the volume of an audio signal. In its most simple form, a noise gate allows a signal to pass through only when it is above a set threshold: the gate is 'open'. If the signal falls below the threshold no signal is...
technique used as a crude method of noise reduction
Noise reduction
Noise reduction is the process of removing noise from a signal.All recording devices, both analogue or digital, have traits which make them susceptible to noise...
and was employed from the beginning of the CinemaScope format.) In theaters that utilized Sensurround and the magnetic stereo prints of Earthquake, the No. 4 (surround) magnetic preamplifier was disconnected and the print's surround track was not used at all. For both mono and mag stereo prints, the Sensurround system itself provided the surround sound effects by feeding the center channel (mag track #2) to the Sensurround horns in the back of the theater. None of the surround channel effects are present in the surround loudspeakers on the 5.1 channel DVD mix of Earthquake—they are all mixed to the front channels.
Furthermore, the DVDs of Battlestar Galactica, Midway and Rollercoaster aren't authentic as the 'rumble' on their tracks is that of the control tones. Because they had no control over the sound system equipment used by home viewers, no attempt was made by Universal to properly reproduce the surround sound effect that was such an integral part of the Sensurround experience.
Surviving Equipment
The last two known original "Sensurround Model-1" control boxes are owned by Dolby LaboratoriesDolby Laboratories
Dolby Laboratories, Inc. , often shortened to Dolby Labs, is an American company specializing in audio noise reduction and audio encoding/compression.-History:...
. They are loaned on occasion for revival screenings of films using the process. At least one replica system exists, as it was custom built for a 2004 London revival screening of Earthquake. Sensurround Mod-II and Mod-III boxes are extremely common and relatively easy to find from old theater equipment dealers and can be bought for $50 or so. The Mod-II and Mod-III boxes were mostly just modifications of the original control boxes, but the changes are not easily undone to make them capable of running "Earthquake" because MCA did all the modifications themselves and never released any documentation about the changes made to each circuit card in the unit.
Cultural References
The alternative pop/rock band They Might Be GiantsThey Might Be Giants
They Might Be Giants is an American alternative rock band formed in 1982 by John Flansburgh and John Linnell. During TMBG's early years Flansburgh and Linnell were frequently accompanied by a drum machine. In the early 1990s, TMBG became a full band. Currently, the members of TMBG are...
released a song entitled "Sensurround" that was incorporated in the soundtrack to Mighty Morphin Power Rangers: The Movie
Mighty Morphin Power Rangers: The Movie
Mighty Morphin Power Rangers: The Movie is a 1995 American superhero action fantasy based on the television series Mighty Morphin Power Rangers on Fox Kids. It featured the characters and actors from the series itself, and used the zords from Ninja Sentai Kakuranger...
and (in a different, faster-paced recording) their EP
Extended play
An EP is a musical recording which contains more music than a single, but is too short to qualify as a full album or LP. The term EP originally referred only to specific types of vinyl records other than 78 rpm standard play records and LP records, but it is now applied to mid-length Compact...
S-E-X-X-Y
S-E-X-X-Y
S-E-X-X-Y is an EP released in 1996 by musical group They Might Be Giants, in conjunction with their LP Factory Showroom.-Notes:...
. The song makes several references to the innovation, especially as used in Earthquake.
An early FoxTrot comic has Jason presenting his dinosuar movie in Sensurround.