A design system that provides realistic sound playback for movie and home theater from THX, Ltd., San Rafael, CA (www.thx.com), an independent spin-off from Lucasfilm, Ltd. The THX Sound System was developed during the production of the Return of the Jedi in 1982 and named after George Lucas' first film, "THX 1138." It has also been known as the "Tomlinson Holman eXperiment," because Holman (Lucasfilm's technical director) was responsible for identifying the criteria for theater acoustics. THX includes a custom design for each movie theater auditorium as well as special speakers and electronics. The company is expected to be a major player in the mass adoption of digital cinema technology.

The THX home theater counterpart is a system of certification that states consumer devices meet certain criteria in each area of the audio/video chain. THX certification is available for DVD players, audio equalizers, A/V receivers, amplifiers, speakers and cables. In 2003, THX entered the automotive audio market, equipping the Lincoln LS sport sedan with the first THX-certified car audio system. THX is entirely compatible with Dolby Digital and DTS. See Dolby Digital and DTS.