Megasound was the name of a movie theater sound system created by Warner Bros. and was officially deployed during the early 1980s.
Warner Bros. used it to provide deep-bass enhancement to premiere engagements for a handful of their features, including: Theaters equipped for Megasound had an additional battery of speakers, consisting subs and horns; usually all were placed on the stage, behind the screen.
However, unlike Sensurround, Warner Bros. never attempted to market Megasound to other studios as a high-fidelity, high-impact bass enhancement sound system.
Encoding Dolby A-type NR (Noise Reduction) on prints meant that each of the six magnetic tracks had less tape hiss.
The processor synthesized (using compression and digital delay) the harmonics of the incoming boom tracks' low-frequency signals (from the LFE) to create incredible deep-bass using a relatively small array of subs and horns.
The bass generation synthesis had a custom cut-off fail-safe @ 16 Hz to prevent risk of structural damage to the presentation venue.
Megasound processing was provided by subharmonic processors such as the Eventide Clockwork Inc. Harmonizer [10][11] or the Aphex Systems Aural Exciter.
Since Megasound was capable of operating into the infrasonic range with a max-low of 16 Hz @ 120db; its bass extension was really unlike or incomparable with any modern sound system.