Sensurround is the brand name for a process developed by Cerwin-Vega in conjunction with Universal Studios to enhance the audio experience during film screenings, specifically for the 1974 film Earthquake. The process was intended for subsequent use and was adopted for four more films, Midway (1976), Rollercoaster (1977), the theatrical version of Saga of a Star World (1978), the Battlestar Galactica pilot, as well as the compilation film Mission Galactica: The Cylon Attack (1979). Sensurround worked by adding extended-range bass for sound effects. 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. Development Original design Sensurround involved the installation of large, low frequency, horn-loaded speakers which contained specially designed 18-inch Cerwin-Vega Model 189 ES 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, designed by D. Broadus "Don" Keele, Jr., to create the low-frequency rumble, using recordings of the 1971 Sylmar earthquake as a reference. Two low frequency