The Deep Note is THX's audio trademark, being a distinctive synthesized crescendo that glissandos from a low rumble to a high pitch. The sound is used on trailers for THX-certified movie theaters, home video, video games, and car infotainment systems.
The Deep Note debuted at the premiere of Return of the Jedi in Los Angeles. Since then, it has gone on to be a pop culture icon both in meme and cult nature.
A Shepard tone, named after Roger Shepard, is a sound consisting of a superposition of sine waves separated by octaves. When played with the bass pitch of the tone moving upward or downward, it is referred to as the Shepard scale. This creates the auditory illusion of a tone that continually ascends or descends in pitch, yet which ultimately seems to get no higher or lower. —Wikipedia
Although there is an international standard that has been agreed to by the ISO and, within Europe, by the EU, copyright laws make it difficult to publish these widely.—Wikipedia