How The THX Noise Was Created

devilsbrigade writes "The blog MusicThing is running an interesting interview with Andy Moorer. Mr. Moorer is the man who created the sound called Deep Note, now heard in every THX-enabled movie theatre. The interview is originally from last year, but the tech-heavy discussion is still a timeless analysis of a great sound." From the article: "The score consists of a C program of about 20,000 lines of code. The output of this program is not the sound itself, but is the sequence of parameters that drives the oscillators on the ASP. That 20,000 lines of code produce about 250,000 lines of statements of the form "set frequency of oscillator X to Y Hertz. The oscillators were not simple - they had 1-pole smoothers on both amplitude and frequency. At the beginning, they form a cluster from 200 to 400 Hz. I randomly assigned and poked the frequencies so they drifted up and down in that range."

Comments

Some tangential "Deep Note" trivia

[doesitmakeitsick]

This always amused me: http://www.benedict.com/Audio/dre/dre.aspx When the Napster maelstrom hit the recording industry, Dr. Dre, along with Metallica, was one of the first to hurl accusations of copyright infringement at the popular file sharing site.

Dr. Dre is furious that people are using Napster to download his song "Lolo" without permission or license - an obvious "copyright infringement". The irony is that the prominent feature of that song is a sound that Dr. Dre appropriated without permission or license - an obvious "copyright infringement"?

Blasting Speaker Noise

[zippthorne]

Their stated goal was to demonstrate the clarity or depth or somesuch without being overpowering..

However every theater I've been in with THX has for some odd reason put the audio level up to 11 to "enhance" the effect. So instead of a nice clean silly-sound followed by a clear and rich sound, I am treated to the sharp buzz of overmod followed by the grating pops of briefly exceeding the specifications of the speakers during the exciting parts of the films.

Fortunately, home theaters are cheap and it is quite easy to peg the audio at a level that doesn't stress the speakers. But it's a sad commentary when $60 walmart home theater has better sound than the real thing simply because some undertrained lacky failed to properly adjust the sound levels.

On Purpose? (Temporal Masking)

[slashbob22]

Much like some of the methods of lossy compression (Temporal Masking). Maybe the point is to provide a loud sound such that your ears cant really distinguish the crappy audio afterwards -- I do realize that temporal masking is generally on the scale of milliseconds. But maybe they know something we don't.

THX, DTS, etc.

[demonbug]

I was trying to remember the first time I heard the "Deep Note", but couldn't. The only thing I could think of was "The Digital Experience" intro at the beginning of Jurassic Park (I think the first or at least one of the first movies released using DTS), but I don't think that was quite the same thing. Really cool though, and it was a great opening for the bone-rattling bass in that movie. Anyone know what the first thing the "Deep Note" was attached to?

Re:THX, DTS, etc.

[kaptron]

According to the link, Return of the Jedi was the first. Of course, I never made it that far in the theater myself, I got scared by a Friday the 13th trailer and went to see another movie (this was the 1985 ROTJ re-release when I was almost 4 yrs old).

But I do distinctly remember the Jurassic Park DTS intro... it seems like around that time was when Dolby Digital, SDDS, etc, surround sound intros started becoming really prominent. I had always thought that the THX intro was a lot newer than 1983 myself, but what do I know.

Many Variations on a theme.

[LibertineR]

I've got a Home Theater Calibration DVD that contains all the recent variations of that THX sound. They made dozens of them. The coolest one? The one made for the movie Aliens, by far. I think they did a few for the Star Wars movies too, and other movies where sound quality was paramount. (no pun intended) It cost a ton of money to get my theater to the point where it sounded just like a cinema, but now it is sometimes the highlight of the movie watching experience. Which says a lot about the quality of movies these days. Only the overhead rumble of the first Star Wars movie matches that THX sound clip in its viceral sound impact, along with the opening segment of Top Gun with the subwoofer cranked up.

TODO: log random number generator seed

[natophonic]

Some months after the piece was released (along with "Return of the Jedi") they lost the original recording. I recreated the piece for them, but they kept complaining that it didn't sound the same. Since my random-number generators were keyed on the time and date, I couldn't reproduce the score of the performance that they liked. I finally found the original version and everybody was happy.

Whew!

I was in a somewhat similar spot a few years back, where a script I'd written to generate random data for load testing a server, used date and time as a rand() seed. One set of data I generated uncovered a weird threading issue, and it was pretty reproducible with that dataset. Then a disk crash wiped the dataset. I still had the script, but couldn't seem to get another dataset that would repro the issue.

In addition to being better about backups, I now log whatever random seed is used to generate a dataset like that.

MythBusters busts it

[tepples]

MythBusters confirms it: Brown note is dying