Does the THX Deep Note Actually Increase in SPL/IL?

1. How the THX Deep Note was made?
2. Why was the THX intro so loud?
3. What is the point of the THX sound?
4. Is the THX Deep Note copyrighted?

How the THX Deep Note was made?

The Deep Note is THX's sound trademark, 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.

Why was the THX intro so loud?

TIL The THX Sound (Deep Note) is perceived louder than it actually is because it has such a large spectrum of frequencies.

What is the point of the THX sound?

The current THX was created on June 12, 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.

Is the THX Deep Note copyrighted?

The sound itself is copyrighted, but here is a problem: The code Dr. Moorer wrote has generative characteristics (i.e. it relies on random number generators), so each time you generate a score and feed the resulting statements to the ASP, the generated sound is somewhat different.