Director Alex Garland’s Ex Machina was one of the most anticipated films at this year’s SXSW Film Festival, where it made its North American premiere. A harrowing exploration of the potential for interaction between human and artificial intelligence, the film introduces us to Ava, an alluring humanoid creation, and Caleb, a programmer who has ostensibly been asked to test her capabilities. As things develop within the remote laboratory setting, the mood becomes increasingly tense — supported in no small part by the film’s mesmerizing soundtrack, created by Geoff Barrow (of Portishead fame) and composer Ben Salisbury.

A minimalist score driven by synths and samples, Barrow and Salisbury’s work helps to shape and direct the viewer’s journey through Ava’s fascinating world. That it’s so precise isn’t by luck, either — the pair worked on the soundtrack for the better part of a year. It marks the latest progression in the ongoing collaboration between the two musicians, who originally met through a local football league (that they still play in). We caught up with Barrow and Salisbury in Austin during SXSW to talk more about Ex Machina, how they approach their work, and what their ultimate goal was for the film’s soundtrack.

How did the two of you first start working together?

Ben: I didn’t actually know that Geoff was Geoff from Portishead for a long time. And I don’t think he knew what I did. We just played football. When we did finally find out, various things came up with Geoff’s record label about doing some strings for an act of his, or collaborating with an artist on his thing. And we both said, “Wouldn’t it be great if a film opportunity came up?” And then Dredd came up.

Geoff: Well, before that, the Banksy film (Exit Through the Gift Shop) that I was a music supervisor on, I did some of the music on it. There was an idea that I was going to do that I spoke to Ben about, but it didn’t end up going in that direction. So we just said, “Okay, let’s make sure that we do work together when it comes up.”

Ben: So Dredd came up, which was Alex’s film before this one. Geoff has a mutual friend with Alex, Richard Russell at XL Records, and he knew that Geoff was a Dredd fan. So we started writing music for the Dredd film. It didn’t last the course, as has been well documented.

Geoff: But we released it as a standalone album, as DROKK, with 2000AD, the comic itself. Alex really liked our music on that, and wanted to continue working with us. And then there was a chance meeting — I met him in an airport in Norway, while I was on tour with Portishead and he was doing some scouting, location stuff for this film. He sent the script out, we started, and we were on it for 10 months, basically, through the whole process.

So would this collaboration not have happened if it wasn’t for that meeting?

Geoff: No, it definitely would have happened.

Ben: He said, after Dredd, when we had to part company, “Don’t worry, next one, we’ll get together.” So we were waiting and hoping that this would get off the ground, and it did.

What was the process like, working on this project for such a long time?

Ben: We read the script, and then about a week into the edit period, we came along and saw the first rough cut, and started from there — which is quite unusual. Normally, on stuff I’ve done in the past, you’re there right at the end of the process, and you get four weeks or so — maybe on a feature film, two or three months — which is fine and is a perfectly valid way of working, but I think Alex wanted us in there from the very beginning. So we were lucky enough to be part of the whole narrative journey of the film, watching different things come in, and different visual effects, and the story slightly changing.

Geoff: So we’ve seen Ava, literally as she was, all the way through. And Alex is involved in every single process of his film. Whether that’s visual effects, whether it’s music, whether it’s the grade, whether it’s sound design, he’s there. He’s just incredibly specific about what he wants, and will argue with you, but in a brilliant way. You know, since his level of quality is so high, that you’re arguing for the right reasons.

Geoff Barrow and Ben Salisbury
Geoff Barrow and Ben Salisbury

Did your approach change at all as things developed?

Ben: Not really. Things changed though. A good example of that might be when we came up with an approach for the building love interest between Caleb and Ava, and I can’t remember at what point, but suddenly we all agreed: maybe he’s falling for her too early. There should be some sort of element of tension within there, and weirdness. So they couldn’t go back and re-shoot; the music is the thing they have at their disposal to change the viewer’s emotional response to when things are happening. It’s quite a simple score sonically, in lots of ways, but it actually had to do a lot of quite complicated jobs. And when it does those jobs is sort of crucial to the narrative and emotional impact of the film at certain points. And that would shift.

Geoff: It is amazing actually, because you can put a vibe under a scene, like a tensioned vibe under a normal conversation, and just change the film completely.

Ben: Sometimes, I suppose, in the traditional way of doing a film score, when it’s given to a composer, those issues might be locked down. Whereas we felt we were part of the process of that coming together. It made it difficult, because once you change one strand there, it’s been decided, “Maybe he shouldn’t be falling for her too hard there” — and when you take out what you’ve done there, it has an impact on that whole strand you might have written. It had a thread, where that cue resonates with this cue — it’s mildly frustrating, but it’s a process, and it’s very satisfying to be that involved.

So how much music was created in total versus what ended up on the soundtrack?

Geoff: It’s more about, you had a vibe going, so you had Ava’s theme; you had the horror and tension and claustrophobia; and basically, when you have something that’s on the right vibe, you would just tweak it. Like when Caleb walks into the room that Ava’s in, before he meets her, and realizes that there’s a crack in the glass, there’s a weird noise that we make, and it’s just where that sits.

The way it works with technology, you’ve got stems, and you record traditional channels of sound. So you’ve got your low one, your mid one, and the high; and then, through editing, you can move them around and play them like a keyboard. It’s almost like playing an orchestra. Does the orchestra swell at that part or does it swell later? But because it’s electronic, it’s a lot easier, because you can draw it in, the swell.

Ben: In terms of how it is as music, there’s not much left on the cutting room floor. There’s only one — the beginning of the film was always a problem, for a reason that’s maybe too complicated to go into. But it was a different beginning, essentially, for a long time. It had the Savages track that’s at the end of the film.

Geoff: There used to be a helicopter scene. There was the Savages track, then the helicopter scene, and that song is such a killer track that when you came out of it — we kept on writing this track for the helicopter scene. We must have done ten versions, and they all had to go, because you would play it out of the Savages track and it just wouldn’t work. And that’s partly the reason that the beginning changed. It looked like it was going to be a Marvel film. It looked amazing, but it’s a dialogue film, not a big action kind of thing, so it kind gave you the wrong way to go into it. Alex came back from the States and got rid of it.

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Are there other films or soundtracks that you find yourselves inspired by?

Ben: You bring with you a whole rucksack full of influences, either consciously or unconsciously. There are loads of great soundtracks, recent soundtracks, like Under the Skin, we both think is incredible. I really love Solaris and we both love Carpenter. The list could go on. It’s almost unfair to single people out. But we didn’t consciously want to reference anyone. It might well be there, though. People might hear things in the score that remind them of someone or something else.

Geoff: What we wanted was a kind of purity in an electronic soundtrack. Without sounding like we’ve done anything greatly different, you listen to a lot of electronic soundtracks, and they all have to compromise somewhere. They all have to have a beat in them; if it’s supposedly Carpenter-esque, there’s always some other filter going on. What we wanted to do was something where, when you hear it, it’s very singular.

Ben: The easy thing to do as a modern score composer is throw the kitchen sink in, and just fill the soundspace up with delays and kodo drums. I’ve been guilty of it, because it’s an easy thing to do. Sample technology is so good, you throw in any old thing and it will sound great. It will sound polished. But it won’t sound particularly interesting. So the one constant is that we tried not to do that.

Ex Machina is in theaters now. To find screenings, visit the film’s official site. The Ex Machina soundtrack is available from all online music retailers, with a 2CD special edition on the way from Invada Records.