Tuesday, October 13, 2015

Mighty Sensurround Turns 40

Looking back, it could possibly be claimed that the launch of Sensurround around 40 years ago was the biggest thing to happen to audio in movies since the invention of the “talkie”. Colour film had been around for years, and black & white movies were only for ‘artsy’ stuff. But adding a new ‘sound’ feature, beyond stereo, pinned hopes on filling cinemas again with enthusiastic patrons.


Sensurround had a short life that was long in development. Only 5 films, released between 1974 and 1979 used the ‘technology’. MCA/Universal proudly launched it with Earthquake. Then came Midway (1976), Rollercoaster (1977), Battlestar Galactica (1978) and its sequel: The Cylon Attack (1979). Cinemas presenting the films had to be fitted with special sound systems (developed by Cerwin-Vega) to reproduce Sensurround, a low deep rumble, in order for the audience to ‘feel’ the effect.



It actually worked. Some cinemas suffered with bits of their interior falling from the roof because of the rumble, while patrons watching films in adjoining auditoria often complained about the vibration next door disturbing their enjoyment of The Godfather Part 2.

MCA/Universal originally only thought of fitting around 30 cinemas with Sensurround. Two years after the release of Earthquake, 2000 cinemas worldwide had the system ready for screening the World War 2 flick Midway.


Interestingly, the ‘rumble’ used to create the sensation was not actually recorded on the film. Optical audio used on film back then could not reproduce frequencies below 40hz, a requirement of the system. Instead, a special ‘control’ track was added to the film, which then triggered the output of the ‘Sensurround rumble generator’ at specific times in the film/s. That rumble was fed directly to the Sensurround amplifiers and speakers in the auditorium. Because of this, merely ‘turning up the bass’ when watching these films at home today does not reproduce the effect.

What killed it? The Sci-Fi slayer of them all! When Star Wars hit the cinemas in 1977, Rollercoaster suffered the fallout. Star Wars didn’t need Sensurround to break those box office records. The movie industry eventually learned that Sensurround was no longer the drawcard for audiences.


It’s thought that only two original "Sensurround Model-1" control systems exist today, both owned by Dolby Laboratories, which kindly loans them for revival screenings of films using the process. A replica system exists, custom built for a 2004 London revival screening of Earthquake. Later versions (Sensurround Mod-II and Mod-III) are more common and can sometimes be seen for sale on eBay.

Sensurround has left a major legacy however. It inspired rival systems and put focus on the capability of what audio can bring to the movies (even at home), and was a major factor in the increase in subwoofer sales and the rise in subwoofer designs in the late 1970s and 1980s.

Perhaps it even inspired what we expect today when DTS, Dolby or THX help bring our movie-going experience to life.

("Sensurround logo" by Source (WP:NFCC#4). Licensed under Fair use)