the encyclopedic entry of sensurround

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Sensurround

Sensurround is a process developed in the 1970s by Universal Studios to enhance the audio experience during the presentation of theatrical movies. Specifically developed to showcase the 1974 film Earthquake, the process was also used in three subsequent films, Midway (1976), Rollercoaster (1977) and in the theatrical version of Saga of a Star World (1978), the Battlestar Galactica pilot. The use of Sensurround created some controversy as theaters were damaged, theater-adjacent businesses disrupted, patrons became sick and in one documented case, a moviegoer suffered cracked ribs.

Development

Original design

Sensurround involved the installation of large, low frequency, horn-loaded speakers which contained specially designed 18-inch Cerwin-Vega Model 189E 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 theatre. 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 deep bass signal fed to the Sensurround horns was controlled by a separate control box in the projection booth. Audio from the film soundtrack was fed to the control box which fed 1,600 watt BGW 750 audio amplifiers driving the speakers. When triggered by control tones on the film's soundtrack, the system generated a pseudorandom noise between 17 and 120 Hertz at sound pressures ranging from 110 dB at the center of the theater to a maximum of 120 dB 4 feet in front of any horn. The resulting rumble could be felt by audience members as well as heard.

In the case of 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 "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 8db at select points to create a greater dynamic range (MCA called this the "Step-Gain" function.) Instead of recording the rumble on the optical or magnetic tracks of the film, an external digital pseudorandom noise generator (contained in the control box) was used because there was no method of recording such deep bass on an optical or magnetic film soundtrack at that time. In addition, while the rumble was of a pseudorandom nature, it was designed to duplicate the waveform of the 1971 Sylmar earthquake.

Sensurround Mod-II

After Earthquake ended its run, MCA re-engineered the Sensurround system to enable the recording of the deep bass on a standard 35mm optical soundtrack, with no external rumble generator being required. In addition, dbx Type-II noise reduction was incorporated to increase the dynamic range and reduce audible noise created by the optical process. MCA also changed the way the control tones worked so that now the Sensurround horns in the front and back of the theater could be controlled separately. This allowed for more creative effects, such as a sound being panned from front to back of the theater, or the rumble alone coming from the back of the theater while voice and music continued in the front. 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 effect, used to good effect in Rollercoaster. 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 86db, superior to 70mm magnetic prints of the time. It also allowed a mono optical track to have surround sound effects; this led MCA to market the system to other studios and producers as a general-purpose high-fidelity sound system. Dolby Stereo optical was just beginning to become known in the industry and MCA felt they had a viable competing format.

Sensurround Mod-III

Mod-III Sensurround was a further refinement of the system to allow much more subtle and impressive effects. It was only used for Battlestar Galactica. Instead of the Sensurround effect being a rumble that could be felt and heard, MOD-III used infrasonic effects that could be felt but NOT heard. Thus, scenes could have dialogue and other audio at standard levels while accompanied by the effect of movement. Or, the infrasonic sounds could be combined with higher frequency sounds to create the effect of wind; this was used in Battlestar Galactica when the Atlantia explodes. And as the Clonial Vipers took off, the infrasonic waves were quickly 'panned' from the back to the front of the theater, creating the sensation of "launching" in the audience. Battlestar Galactica used the Sensurround system in innovative ways.

Sensurround was highly successful. By 1976, when Midway opened, there were over 800 Sensurround equipped theaters in the USA alone - worldwide, there were over 2000 Sensurround 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. 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. Interestingly, the Academy Theater in LA uses a group of four Model-W Sensurround horns in the front of the theater under the screen. Cerwin-Vega still sells a horn loaded subwoofer containing a modern 189E driver, but the bass of the horn cuts off at 25 Hz, so it can, in no way, produce the effect of the original system.

Noise complaints

The much-hyped Sensurround made Earthquake a popular "event" film in 1974 as it became one of the largest grossing films of the year, but the gimmick never caught on during the age of budding multiplex cinemas due to disturbances it caused at theatres. When Earthquake opened in November of 1974, The Godfather, Part II opened the same month and often played in the adjacent auditorium. Theatre managers were inundated with complaints from audience members when Sensurround would literally shake the theatre exhibiting Godfather II. This disruption was not worth the effort for most theatre owners, nor was the $500 per week Sensurround rental fee charged by Universal.

The excessively loud Sensurround caused additional disruptions for theatres playing Earthquake, including structural damage in some cinemas. At Mann's Chinese Theatre in Hollywood, theatre management strung a safety net over the seating to catch errant pieces of plaster after a test screening revealed the process had actually cracked the ceiling. In Germany, Sensurround movies were only allowed to be played in single screen cinemas. When Earthquake was screened in Chicago, the head of the Chicago Building and Safety Department demanded that the system be turned down or removed, due to his concern that it would cause structural damage to city theatres.

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 Award 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.

Remastering for DVD

DVD prints of Earthquake from Universal Home Video, released after May 9, 2006, feature the Sensurround track (described as "Sensurround 3.1" which is an update to "Sensurround III"). In this case, the Sensurround 3.1 soundtrack is just the mono soundtrack fed to the 3 front speakers and the subwoofer; it is not a duplication of the Sensurround system, and neither is the 5.1 soundtrack. 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 examples

The last two, known, original surviving "Sensurround Model-1" control boxes are owned by Dolby Laboratories, and 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.

Competing processes

Following the success of Sensurround, other studios devised similar technologies to mimic its effects. 20th Century-Fox 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).

Cultural references

The alternative pop/rock band They Might Be Giants have a song called "Sensurround", which appeared on 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 theatrical audio technique, specifically to the film Earthquake.

Edward Ka-Spel of The Legendary Pink Dots mentions "Holy, holy Sensurround" in "Damien" from the album "...and from here you'll watch the world go by" and "Cola SenSurround" in "Just a Lifetime" from the album "The Crushed Velvet Apocalypse" (full context: "Hunting the oasis but there's only cola-sensurround. A technicolour thrill... it costs a fortune, so it must be real").

In a FoxTrot strip, Jason Fox uses Sensurround when showing a homemade claymation dinosaur movie to his class. In another Foxtrot strip, Peter Fox tries to make his own Sensurround by chugging cola and watching the Apollo 13 launch.

The Sex Pistols song Holidays in the Sun features the line: "In sensurround sound in a two inch wall / I was waiting for the communist call / I didn't ask for sunshine and I got world war three"

The Fabulous Poodles song B-Movies has the following stanza; "It’s all Dolby sounds and monster screams & sensurround disaster themes B-Movies always fill my dreams"

In their song "Elevator Muzik," which criticizes American commercialism, the Christian rock group Resurrection Band features the lyric, "...soon we'll be shopping in Sensurround!" The song can be found on their 1981 release Mommy Don't Love Daddy Anymore.

Elements of the 1993 film Matinee seems to parody Sensurround. The film itself revolves around a movie theatre using techniques such as Atomo-Vision and Rumble-Rama to screen the fictional film 'MANT'.

The Kentucky Fried Movie spoofs Sensurround with a concept called "Feel Around". Each movie-goer is given an usher who touches them in a way that reflects the action on the screen.