Uploaded January 2016 | Updated September 2026, 2 weeks ago
In 1974 Universal Studios released the film "Earthquake". To enhance the experience, the audio equipment manufacturer Cerwin-Vega, working with Universal, developed a sound system to create low-frequency effects to simulate an actual earthquake.
The Sensurround System they created introduced movie audiences to the subwoofer.
It worked this way. Instead of mixing the rumbles, which could be as much as 35 dB louder than the dialog, into the movie's soundtrack, Sensurround used 25 Hz and a 35 Hz control tones , that could trigger two different effects. These tones would either be at low levels on the mono audio track or for some prints could be on separate audio tracks. The frequency and volume of the tones would trigger a pseudorandom noise generator that could, when coupled with the amplifiers and subwoofers, create an earthquake-like rumble at 120 dB.
Sensurround in some ways is similar to Fantasound, that was developed in 1939 for the Disney film "Fantasia", in that tones on a control track turned the amplifiers up and down.
Initially it was proposed that Sensurround might even have dust fall from the ceiling during the earthquake scenes. However, and perhaps very wisely, they chose not to do that.
Theaters had to be modified to be able to play Sensurround, and that often meant rows of seats had to be removed to accommodate the large subwoofers.
Today, subwoofers are a standard feature of movie theater sound systems, and low-frequency effects, like rumbles from earthquakes, explosions, gunshots, and crashes are included in almost all movie soundtracks.
In 1974 Universal Studios released the film "Earthquake". To enhance the experience, the audio equipment manufacturer Cerwin-Vega, working with Universal, developed a sound system to create low-frequency effects to simulate an actual earthquake.
The Sensurround System they created introduced movie audiences to the subwoofer.
It worked this way. Instead of mixing the rumbles, which could be as much as 35 dB louder than the dialog, into the movie's soundtrack, Sensurround used 25 Hz and a 35 Hz control tones , that could trigger two different effects. These tones would either be at low levels on the mono audio track or for some prints could be on separate audio tracks. The frequency and volume of the tones would trigger a pseudorandom noise generator that could, when coupled with the amplifiers and subwoofers, create an earthquake-like rumble at 120 dB.
Sensurround in some ways is similar to Fantasound, that was developed in 1939 for the Disney film "Fantasia", in that tones on a control track turned the amplifiers up and down.
Initially it was proposed that Sensurround might even have dust fall from the ceiling during the earthquake scenes. However, and perhaps very wisely, they chose not to do that.
Theaters had to be modified to be able to play Sensurround, and that often meant rows of seats had to be removed to accommodate the large subwoofers.
Today, subwoofers are a standard feature of movie theater sound systems, and low-frequency effects, like rumbles from earthquakes, explosions, gunshots, and crashes are included in almost all movie soundtracks.
