THX is a high-fidelity audio/visual reproduction standard for movie theaters, screening rooms, home theaters, computer speakers, gaming consoles, and car audio systems. The current THX was created in 2002 when it spun off from Lucasfilm Ltd. THX was developed by Tomlinson Holman at George Lucas's company, Lucasfilm, in 1983 to ensure that the soundtrack for the third Star Wars film, Return of the Jedi, would be accurately reproduced in the best venues. THX was named after Holman, with the "X" standing for "crossover" as well as an homage to Lucas's first film, THX 1138. The distinctive crescendo used in the THX trailers, created by Holman's coworker James A. Moorer, is known as the "Deep Note".
The THX system is not a recording technology, and it does not specify a sound recording format: all sound formats, whether digital (Dolby Digital, SDDS) or analog (Dolby Stereo, Ultra-Stereo), can be "shown in THX." THX is mainly a quality assurance system. THX-certified theaters provide a high-quality, predictable playback environment to ensure that any film soundtrack mixed in THX will sound as near as possible to the intentions of the mixing engineer. THX also provides certified theaters with a special crossover circuit whose use is part of the standard. Certification of an auditorium entails specific acoustic and other technical requirements; architectural requirements include a floating floor, baffled and acoustically treated walls, no parallel walls (to reduce standing waves), a perforated screen (to allow center channel continuity), and NC30 rating for background noise.
THX is currently owned by sound card manufacturer Creative Labs, which holds a 60% share of the company. The company has had a long history with Creative, and was responsible for the creation of the first THX-certified audio card for computers, the Sound Blaster Audigy 2.