The ‘Star Wars’-Inspired History of the Iconic THX Audio Logo


Digital audio engineer James A. Moorer has had an impressive career: He holds multiple patents, has won an Oscar and an Emmy, and was involved in the founding of Stanford’s Center for Computer Research in Music and Acoustics.

But his most famous and familiar work is something that came together in just four days back in the early 1980s. You’ve heard it if you’ve gone to the movies since then, and maybe even if you haven’t. It starts quietly, and it doesn’t last long, but it quickly swirls and builds a kind of thundering tone that can’t be ignored.

It’s the “audio logo” that announces that you’re in a THX-ready theater. It even has a name: Deep Note.

“My wife and I have a running joke,” Moorer told me in a recent interview, “of me going to my grave being famous for 35 seconds.”

The backstory is a curious and seldom-told tale. Among other things, while countless people have heard this brief but mighty composition, most non audiophiles don’t know what, exactly, THX is.

As it happens, Deep Note has just been updated — for the first time in its three-decades-plus history. A new trailer will start booming through theaters in the days ahead. (You can check it out below.)

This makes for a great excuse to revisit the story behind this unusual bit of sound history, along with the momentous yet misunderstood chapter in audio technology that it represents.

What is THX, anyway?


Moorer in the Lucasfilm Tech Building in San Rafael, Calif., around 1983 (top); Moorer at THX Ltd. San Francisco headquarters in 2014 during his visit to work on the regenerated THX Deep Note. (Photos: © THX Ltd.)

First, let’s get clear on what THX refers to. It is not, as many mistakenly assume, a system for recording, encoding, and decoding audio, like Dolby Digital. It has nothing to do with how sound is captured; multiple formats, Dolby included, can be heard “in THX.”

Instead, THX is essentially a certification system. It originally vouched for the quality of the playback sound system in a theater — a kind of sonic-entertainment Good Housekeeping Seal of Approval. The goal was to guarantee to moviegoers that what they were hearing was as close as technologically possible to what the filmmakers intended them to hear.

As is so often the case, the reasons why this was deemed necessary can be traced back to Star Wars.

READ: The Easy and Free Way to Optimize Your New HDTV’s Picture and Sound

While gearing up for the premiere of Star Wars: Episode V — The Empire Strikes Back, a Lucasfilm team was appalled by the condition of the sound system at a certain San Francisco theater. Of the three top-end speakers behind the cinema screen, one wasn’t working and another faced the wrong direction. They were “horrified,” Moorer recalled.

The upshot: In the run-up to the subsequent Star Wars film (Return of the Jedi), Lucasfilm sound specialist Tomlinson Holman led an effort to hammer out proper technical and equipment specs that theaters would need to present the film properly — and would thus qualify meeting the brand-new THX standard. (The name is a nod to Holman’s initials and also alludes to the title of George Lucas’s first film, THX 1138.)

THX took hold and eventually spun off as its own business in 2002. Along the way, it expanded to offer a variety of consulting, license-technology, and certification services relating to both the visual and audio quality of in-home, auto, and cinematic entertainment systems.

According to its site, there are around 2,000 THX-certified theaters today. But when Return of the Jedi made its 1983 debut, rolling out the new THX standard required some fanfare. This took the form of a trailer produced at Lucasfilm, where Moorer worked in the audio unit of the company’s “computer division.” He was also a trained musician and sometime composer.

He recalled his sound-making assignment, as delivered by the guy in charge of putting the trailer together: “I want something that comes out of nowhere and gets really, really big.”

That was it: the entire creative brief for someone who had never been asked to create an audio logo or anything like it. Oh, and it was due by the end of the week.

And yet, Moorer remembered, “as soon as he said it, I knew exactly what I wanted to do.”

‘Pure electronic music’

To untrained ears (mine, for example), the 30-second rising swell of Deep Note resembles the tones of a pipe organ. In fact, the sounds were computer-generated — “pure electronic music,” as Moorer put it.

He spent two days writing 20,000 lines of code to program a whopping mainframe-style audio-processing computer at Lucasfilm. The code drove oscillators producing sounds that he calls “voices” at various frequencies and essentially blended 30 of these tones into a slow-boil crescendo — one that sounded a little different every time the code was executed because of built-in randomness factors. (You can read a detailed description of Moorer’s process at


Moorer in Lucasfilm’s “machine room” in the 1980s (top); Moorer in 2014.

As Moorer put it to me, his program “guided the notes.” The “voices” would go up and down, “wandering around” differently every time. He settled on a version that featured “a conspicuous bass note that went straight down and stood out,” he said. “That’s the one I took to the recording stage.”

Ironically, the now-familiar result didn’t quite fulfill its utilitarian task: THX creator Holman pointed out that the composition didn’t bring out the crystal-clear highs that were likely the new system’s strongest feature, Moorer said, but concluded that “it sounds all right; we’ll go with it.”

Good call. Deep Note became one of the most iconic audio logos ever; THX offers a collection of trailers (same Deep Note, different graphics) on its website. Of course, there are a slew of YouTube riffs involving people trying to re-create the sound or just having fun with it. It’s also been parodied more than once — most famously, perhaps, on The Simpsons.

Fast-forward to today; as Louis Cacciuttolo, THX executive vice president of international business development and brand strategy, readily concedes, most people associate the firm with Moorer’s creation.

“When you ask people, ‘What does THX mean to you?’ most people will try to sing Deep Note,” Cacciuttolo told me. “It’s funny.”

It’s an odd scenario, really — as if everybody recognized the swoosh but weren’t clear on the nature of Nike’s business. But maybe this explains why THX is attempting to publicize the latest improvements to its sound-system standards, which reflect a range of high-end audio improvements in both cinematic and home-entertainment settings. And it might also explain why the company asked Moorer himself to revisit and “reinvigorate” Deep Note.


Moorer in the 1980s (top) and in 2014.

Turns out this was something he’d always wanted to do. Working off of his original computer-code “score” but of course using technology that was wildly more powerful (and convenient) than that original mainframe provided, Moorer created new versions that stick to the basic Deep Note idea but enhance it with more “voices” — up to 80 for the one that will play in the most acoustically sophisticated theatrical settings.

This time around, he had weeks to fine-tune things and was thoroughly satisfied to hear the results in a theater setting at Lucasfilm’s Skywalker Ranch.

“I kept thinking: That’s the way I wanted it to sound originally,” Moorer told me. “I think it’s as far as you can take it.

"Next time," he conceded, "it’ll have to be a different idea.”

Follow Rob Walker on Twitter or Facebook. Thanks to Marc Weidenbaum, of, for audio-logo insights and suggested lines of inquiry with James A. Moorer.