When Lana and Lilly Wachowski’s The Matrix hit theaters in March 1999, it was a landmark moment for cinema at the beginning of what would come to be considered one of the great years for the form. Here was a smart, sleek and above all fresh theatrical experience the likes of which audiences had never seen … or heard.

Among the four Academy Awards the film claimed a full year later was an honor for supervising sound editor Dane A. Davis’ innovative aural designs. His work played a key role in plunging audiences into the Wachowskis’ rabbit hole, a sci-fi vision of life as a simulation in a postapocalyptic, machine-controlled future.

The earliest conceptions were about how to define the two separate worlds presented onscreen: that of “the Matrix,” the virtual reality humans experience as fed to their physical forms, which serve as energy sources for the machines, and that of a “real world” landscape that finds the Earth rendered a scorched husk littered with the accoutrements of a war the humans lost.

“Their number one note was everything in the real world is made from junk and spare parts left over from the wars with the machines. Everything had to sound obsolete,” Davis says, looking back on how the foundation of what would become an entire franchise’s soundscape was born. “And then the virtual world, we had to make up all the rules. For the Wachowskis, everything just comes from a storytelling point of view. So most of the conversations were not about sound. They were just about the subjectivity: ‘Whose experience is the audience having at this time?’”

Keanu Reeves as Neo/Thomas Anderson and Yahya Abdul-Mateen II as Morpheus in Warner Bros. Pictures, Village Roadshow Pictures and Venus Castina Productions’ 'The Matrix Resurrections,' a Warner Bros. Pictures release.

Davis had to abandon some of his wildest ideas, such as the notion that the busier the virtual world becomes in that first film, the busier the machinery manifesting it as a simulation might get. He had intended to have the audience hear the stopping and starting of sound effects as things would get chattery and low-res—somewhat inspired by late-1990s technology, in fact. “The characters lived in a world of partial buffering and everything had that halfway deconstructed quality,” Davis explains. “But the Wachowskis were like, ‘The audience won’t intellectualize it.’ For me it’s all about psychology and I have my own approach, but for them, it’s like, ‘Is the audience in this dramatic moment?’”

Ultimately, The Matrix and its subsequent sequels—The Matrix Reloaded, The Matrix Revolutions and now, 18 years later, The Matrix Resurrections, a solo outing this time by Lana Wachowski—provided a wildly entertaining, thought-provoking and certainly fun sandbox for Davis to play in. After all, it’s an onscreen universe of detailed technology, action-packed fight sequences and just general sonic mayhem. But what would become a signature characteristic throughout all four films is “the code.” The code is everything. It’s the DNA of a shared illusory experience as generated by the machines that farm humans for battery power. It’s a heady concept and, throughout the franchise, an evolutionary one as well.

“The Wachowskis felt the code had to sound electrical and wet at the same time, and that’s kind of contradictory,” Davis says. “But from my point of view, there are five generations of code, which was always a key component of the texture. We feel that code. It changes the way we feel the virtual world. It sort of imbues that virtual world with that electricity and that wetness.”

Those “generations” refer to the fact that, within the story line, there have been multiple stabs at the Matrix and, like any software, it’s constantly being upgraded and patched. The code serves as the interface to the virtual world, and it becomes a central plot element from scene one in The Matrix Resurrections, when it’s discovered that someone is running old Matrix code (i.e., sequences from the original film—things get very meta here), for purposes unknown.

Keanu Reeves as Neo/Thomas Anderson and Carrie-Anne Moss as Trinity in Warner Bros. Pictures, Village Roadshow Pictures and Venus Castina Productions’ 'The Matrix Resurrections,' a Warner Bros. Pictures release.

“What I got to do was go from the original, the old code that people refer to in the film, to what I call ancient code, which is sort of the ancestor of old code,” Davis says. “Because when Thomas [Keanu Reeves] builds a Modal and he goes inside of it and he’s looking around in the city downtown, you see sort of a suggestion of that decomposition of reality in the code. I knew that we couldn’t just use code sounds. It’s a different experience. He’s inside of it. So, I used like a grandparent of the final product of code in the first movie, which is a deeper, lower, clunkier kind of sound.”

Beyond the code, there were two other key aspects that represented the franchise’s sonic evolution. First, the new film introduces “Synthients” to the mythos, machines that interact with humans as part of the resistance against their malevolent counterparts. (Think of the Star Wars films’ ever-present droids.) Davis says he had to develop a range of propulsion sounds and a mechanical “vocabulary” for these various bots.

The other level-up came in the fight sequences, which have of course been a staple of The Matrix action since the wire-fu days of the previous entries.

“The new Matrix needed to sound reminiscent of the old Matrix, but with an even more exaggerated dangerousness and intimate painful detail,” Davis says. “To achieve this, I went back to original recordings I had made of body hits, mostly with three professional jujitsu fighters that beat the crap out of each other for days in my iso-booth, and used vastly better audio tools we have today to create a new vicious and visceral library.”

Again, it’s quite the rabbit hole. But it’s all in service of telling the story, always the North Star no matter how conceptually intoxicating the ideas become. All the more important, then, that the essentials remain grounded, lest audiences lose their grip on the proceedings. That’s where supervising sound editor Stephanie Flack’s talents come into play. Flack’s history with the series began with dialogue editing duties on The Matrix Reloaded in 2003.

“The dialogue back then was still challenging,” she recalls of the earlier films. “We did very little ADR back in those movies, but a lot of the dialogue from Neo and Trinity was very, very low-level, and we just didn’t have the tools available that we do have now.”

Today, with programs like Auto-Align Post to help develop a robust, rich vocal track and RX tools that assist in cleaning up background noise, she’s able to be even more surgical—and obsessive—in her pursuit of precision.

Keanu Reeves as Neo/Thomas Anderson in Warner Bros. Pictures, Village Roadshow Pictures and Venus Castina Productions’ 'The Matrix Resurrections,' a Warner Bros. Pictures release.

“The most important thing for dialogue, always, in essence, is to be intelligible, for it to have clarity and diction, and that is not always a given with what we get from set, because shooting on location is fraught with problems and challenges,” Flack says. “I kind of developed this microsurgical approach. I’m always taking little bits and pieces—it’s kind of like Photoshopping—from other alternate production takes, and taking little pieces of ADR, whether it’s just a consonant or a vowel or something like that, and kind of engineering a scaffolding system for the dialogue, so that it folds into it, it interweaves to give you clarity.”

Adds Davis with a note of pride: “And the Wachowskis have become very dependent on that.”

This is all merely scraping the tip of the iceberg. There are sequences in The Matrix Resurrections that probably shouldn’t be spoiled by discussing them at length just yet. One in particular finds a new application of “bullet time,” the trippy visual effect that depicts how the Matrix-enlightened can move like superheroes through the simulated world. Without getting into too much detail, it involved multiple actors shot at varying frame rates to produce the effect of one moving in ultra-slow motion and the other at ultra-fast motion. Flack says it was the most challenging sequence to work through.

“Quite a lot of that is all cheated dialogue,” she says. “It just takes a lot of finagling to make it look good. And also, if you’re kind of weaving in and out of ADR, the challenge is to always keep the emotion, the original integrity of the performance, and to make it seamless and imperceptible.”

It all makes for one giant magic trick and, for a movie franchise celebrated for its visuals, it’s a good reminder of how equally vital the work of the sound teams has been in generating the world of The Matrix. Working alongside Davis and Flack were re-recording mixers Matthias Lempert and Lars Ginzel, while Barry O’Sullivan handled production mix duties.

“I live in the rabbit hole,” Davis says. “And it’s all about defining the rabbit hole. I do a lot of different genres, Steph and I together. More straight-ahead, sci-fi, fantasy. I’ve done a lot of action movies. But in every genre, and then in every movie and every director’s version of that genre, there are rules that you have to define. Because that has a lot to do with the experience of the audience. I think for The Matrix, it is very heady and fun because we can make it all up.”