The Earthquaking, Subwoofing Magic of Sensurround

Two generations of partiers have felt that clothing-rippling rumble at the rave, the undulating walls of the underground, a festival’s phalanx of whomp. Beyond what you hear from the stacks of speakers, the air seems to vibrate around you. This contemporary bass effect traces itself, beyond any psychotropic symptoms and sound engineering prowess, back to a surprisingly meek source: A teenager huddled under his bedroom desk in early 1970s Los Angeles.

That teenager was Rocky Lang, son of famed movie producer Jennings Lang, whose 1974 blockbuster Earthquake gave birth to the “Sensurround” soundsystem – and sparked the development of the first widely-used subwoofer design. Sensurround popularized the idea of using sub-audio bass frequencies in theaters and, later, on dancefloors. The Sensurround system’s unique folded-horn speaker design, invented by Gene Czerwinski of Cerwin-Vega, became a staple of the disco craze and has influenced nightclub, concert hall and home theater soundsystems ever since. So how did a star-studded ’70s disaster flick starring Charlton Heston and Ava Gardner lead to today’s floor-melting heaters?

A former executive of MCA/Universal Television who helped pioneer the prime-time made-for-TV movie, Jennings Lang saw the extent to which television and impending recording technologies like the VCR were direct competition to movies. His notion was to turn movies from passive audience entertainments into “events,” drawing people to the theater.

“He was always looking for ways to expand the experience of film,” Rocky says of his father. “The term ‘event,’ which is now used for everything in the world, was first used for Earthquake, because his idea was that the movie industry needed to change and try new things. He was ahead of the game, in that he was well aware of what was happening with television, and he knew people needed more of a reason to get them out of the house.”

“The genesis of the whole idea of the Earthquake film came from me,” says Rocky, a Hollywood historian, author and filmmaker. “There was a large tremor in Los Angeles, and my father came running into my bedroom. He found me hiding under my desk, because that’s what we were taught in school – to duck and cover.”

Seeing Rocky curled up on the floor was a eureka moment for his father. Earthquakes, and disasters in general, were in the air. The recent Sylmar quake of 1971 that hit San Fernando Valley rocked Los Angeles and killed 64 people. And Hollywood was heading into the golden age of disaster movies, lavishly budgeted spectacles that packed in big celebrities – many whose careers were on the wane – and even bigger special effects. The 1970 movie Airport, about a suicidal bomber who attempts to blow-up a Boeing 707 laden with Hollywood royalty, unexpectedly scored more than $100 million at the box office and ten Oscar nominations. The race was on to see what major motion picture catastrophe could next haul in the cash and cachet.

Why not an earthquake movie, thought Lang, but one that operated like an amusement park ride, with a reverberating soundsystem that could shake the cinema itself? Theatrical gimmicks were hardly unheard of, from perfume-pumping 1960s special effects like Smell-O-Vision and AromaRama to schlockmeister William Castle’s “Percepto!” device, hardwired into theater seats to give viewers an electrifying jolt during horror flick The Tingler. Lang’s scheme would require more technical finesse, however. Most film audio tracks and theater speakers couldn’t generate frequency signals low enough to give the quaking effect. Beyond the rumble, too, Lang wanted to devise a system that enveloped the moviegoer in sound, with speakers placed around the room and cues on the soundtrack that would transmit certain sounds to certain locations. He approached the Universal City Studios Sound Department about making Sensurround a reality.

“Motion pictures at that time had such a limited range of fidelity,” says Ben Burtt, sound designer for Star Wars, Star Trek and E.T., on the new Blu-Ray edition of Earthquake from Shout Factory. “You couldn’t reproduce what the whole range of the human ear would experience. It had been that way for decades, because the physical soundtrack, the little white squiggly line on the film, was of limited quality, like something filtered through a radio. Universal came along and realized that the sound in a music studio at the time was so much better than a theater. They came up with the idea to work with Cerwin-Vega to develop the process called Sensurround.”

Cerwin-Vega was founded in 1954 by aerospace engineer Eugene J. “Gene” Czerwinski, who had an irrepressible drive to expand the qualities of amplified sound. By the early ’70s, his company was already well-known for producing cutting-edge speakers and amplifiers with extraordinary fidelity, and Cerwin-Vega was working with acts like the Rolling Stones and David Bowie on specially designed concert and recording setups.

“Gene was essentially an iconoclast to the core, having embraced the folk-rock and protest culture of the late ’60s,” wrote his close friend and former employee, audio engineer Drew Daniels, in a remembrance after Czerwinski’s death in 2010. “Gene was an engineer’s engineer. His mastery of solid state, AC, DC, electromagnetics and thermodynamics was top flight. It was routine for Gene to draw an amplifier schematic on one side of an A-size quadrille page using only a slide rule and some reference books and charts. He would simply hand me the sheet of paper and say, ‘Go build this.’”

Perhaps realizing the commercial potential of Sensurround, Czerwinski was the driving force behind its development, working with Universal’s W.O. Watson, Richard J. Stumpf and Robert J. Leonard to solve the riddle: how to generate a sound in the theater so low that no existing speaker could play it? The specialists experimented on the Universal Studios lot, building huge speaker cabinets and bringing in test audiences for each attempt to make sure they were getting the right effect. Watson told American Cinematographer in 1974, “When I saw the Earthquake script I realized that we would be able to come up with a form of audience participation – something that would make the viewers feel that they were part of the action that was going on. Our first demonstration was made using some very high-powered speakers and amplifiers.”

In the end, they came up with an ingenious solution. When it was time for the theater to quake, the soundtrack played two inaudible “control tones.” These tones would trigger a special Sensurround box, which would use what was called a pseudorandom noise generator to create the low frequency rumble, sending it out to the amplifiers in the specially constructed speakers. The speaker’s horns had been folded inward – in “W,” “M,” and “C” formations –to allow their path-length to be long enough to generate the power needed to amplify the rumble, while still being able to fit inside the speaker cabinet.

When the amplifiers were fully engaged, they could produce sound between 100 and 120 decibels, at frequencies as low as 15 Hz – creating a wave that vibrated the air in the theater, using the flooring and walls themselves as conduits. This meant that viewers not only heard the earthquake, they felt it in their ribcages. According to Watson, “We generate both sub-audible and audible frequencies that actually vibrate the torso and the diaphragm inside the body. You feel something going on in your flesh and the auditory nerves are also responding to the sensation. The viewer feels that the building is shaking. It isn’t really, but it feels that way. If you touch a thin plaster wall in the theater, or if you touch a seat that has metal in it, you find that the seats actually vibrating.”

The Sensurround speaker cabinets themselves were enormous and had to be individually installed in each theater that would play the movie. Entire rows of seats had to be removed at considerable expense to owners, who risked physical damage to their buildings. Installation took up to three days and involved a fleet of inspectors checking for correct electrical specifications and structural integrity. For the movie’s debut at Grauman’s Chinese Theatre in Hollywood, every inch of the theater, from the basement pipes to overhead chandelier, had to be inspected and secured. A giant fishnet was spread across the ceiling to catch any falling plaster.

Nobody knew if Earthquake would be worth it. It was coming out around the same time as two other disaster films that helped anchor the golden age of genre, The Towering Inferno and Airport 1975, and just in the wake of The Poseidon Adventure. The studio had spent seven million dollars making the movie, and the often hammy dialogue and sometimes baffling editing makes it at times hard to follow, or swallow. The film’s effects are very well-executed – who can resist a giant tremblor and its aftershocks leveling downtown Los Angeles? – although the film’s biggest special effect (beyond making us believe that lovely Genevieve Bujold would fall for leathery Charlton Heston) might be how well Victoria Principal’s perfectly coiffed two-foot afro survives multiple aftershocks. And gorgeous set paintings by Albert Whitlock, some old-fashioned scenery-chewing by Ava Gardner and a score by John Williams that knows to keep quiet during the fun, quake-y part makes it all enjoyable.

Luckily for Universal, audiences flocked to the novelty experience despite critics’ misgivings, and cinemas throughout the country rushed to install the special soundsystem. Soon there were 800 systems worldwide, with 400 in the United States. Cerwin-Vega and the Universal Studios team won an Oscar for developing Sensurround, and Earthquake won one for Best Sound. “Sensurround was ridiculed as a noisy, cheesy gimmick by some, but it was truly a stroke of marketing genius – one that delivered sensation both in theater auditoriums and at the box office,” says Dean Lamanna, an entertainment journalist and historian who is working on a book about the disaster film genre.

“For general audiences, it suitably enhanced the ambitious, if sometimes uneven, visual effects and multi-character drama. Most moviegoers left feeling like they got plenty of shake, rattle and roll for their buck. Driven by the international appeal of its subject matter and Sensurround, the film sold 41 million admissions worldwide by the end of its run in 1976. It helped rouse Universal Studios from a years-long financial malaise and made Jennings Lang, who was already a respected and well-liked production executive, a true superstar on the studio lot.”

Sensurround took Europe by storm, too. “I could feel the air move around my trousers, it was simply staggering,” says Thomas Hauerslav, a former theater projectionist in Copenhagen who is now an expert in the history of 70mm film. “I have never experienced cinema sound, or anything like it, since, and that includes all the fancy digital cinema soundsystems with a gazillion loudspeakers we have today. Sensurround was the ‘mother’ of low frequency in cinemas, and proved that a real dynamic soundtrack could be added to motion pictures when most films in those days were either mono, or some variation of four to six-channel magnetic sound. Sensurround suddenly added an entire new medium to motion pictures.”

Earthquake was followed up by the 1976 war movie Midway, full of buzzing planes and explosions, and 1977’s Rollercoaster, the tale of a fiendish amusement park saboteur. But the novelty had dwindled by the time Sensurround-equipped theaters were showing Battlestar Galactica features in 1978. Film audio track and speaker system technology was catching up to Sensurround without the need for hulking speakers. “Today it’s routine to have a special track devoted to low frequencies,” said Ben Burtt. “The current technology accommodates that, it’s normal. Sensurround was the beginning of that idea.”

As Sensurround speakers were being torn out of cinemas, versions of them were filling nightclubs. Earthquake had set off a desire for national desire for more bass, especially on dancefloors during the burgeoning disco craze, and Cerwin-Vega was happy to fulfill it. Czerwinki’s early folded-horn speakers were prototypes for the subwoofer, which could deliver more thump in the club. Legendary club sound engineers Alex Rosner of the Loft and Richard “Dick” Long of Paradise Garage had come up with their own specialty sub-bass soundsystem adaptations (Long’s was called the Levan Horn after Larry Levan), to create a haptic quality where the music could be felt as well as heard. But it was Czerwinski’s system that was reproduced and marketed quickly.

Suddenly, nightclubs had to have “Earthquake bins,” and Cerwin-Vega developed its series “E” subwoofers to fill this demand. “Disco people want to feel the music,” the company’s technical director told Billboard magazine in 1975, “and that takes plenty of clean bass. More clubs are turning to Cerwin-Vega speakers and we’re getting special requests for the identical speakers used for the Sensurround effect used in Earthquake.” And dance music was adapting to these new bass possibilities. 12" records, with wider grooves that prevented needles from skipping as much, were becoming more common, and were being engineered to include more bass volume and lower frequencies.

Czerwinski also knew that one way to corner the market during a craze is to spread your ideas around so people can compare. “I think one of the most long-lasting designs that my father came up with was a folded-horn bass,” Connie Czerwinski, Gene’s daughter and former president of Cerwin-Vega, said. “He was famous for it, and it’s one of the designs he gave away to Fender, Acoustic, Sun and Vox. That was our meat and potatoes product for years and years. Where he really shined, he had his own special flair for designing woofers. If you get a JBL next to a Cerwin-Vega, they have a very different sound.”

According to the company, Cerwin-Vega’s speaker series “E” remains one of its bestselling of all time. The company still sells folded-horn bass systems called “Earthquake” and “Junior Earthquake,” although neither of them come with Charlton Heston.