The Deep Note is the sound trademark of THX Ltd., being a distinctive synthesized crescendo that glissandos from a relatively narrow frequency spread (about 200–400 Hz) to a broader frequency spread (of about three octaves). It was created by James A. Moorer, a former employee of Lucasfilm's Computer Division in late 1982. The sound is used on trailers for THX-certified movie theaters, home video releases, video games, and in-car entertainment systems.