There's a standard line in awards-watching circles that voters often confuse Best Sound with Most Sound, but yesterday's nominations for the Cinema Audio Society awards didn't quite bear that out. Nestled between the thundering action of “The Hobbit” and “Skyfall,” and the showy live-vocal capture of “Les Mis,” we had the soft, chamber-y echoes of “Lincoln” and, most interestingly of all, “Zero Dark Thirty” – a film that takes a refreshingly understated sonic approach to territory Hollywood tends to fill with cacophonous fireworks.

This isn't the first time Swedish-born sound designer Paul N.J. Ottosson has been recognized for his muscular-but-delicate artistry on a Kathryn Bigelow thriller – three years ago, with collaborator Ray Beckett, he won the CAS Award, not to mention two Oscars, for his unnerving soundscapes on “The Hurt Locker.” That film, with its narrative expressly based around explosives, was a sound man's playground, compared to which “Zero Dark Thirty” concentrates its pyrotechnics in shorter bursts.

Laymen will, of course, feel the effects of Ottosson's work most in the film's pummelling action sequences, climaxing with a nerve-shredding Navy SEAL raid on Osama Bin Laden's compound, but listen closer and there's as much rich sonic texture in the film's quieter labyrinth of CIA office politics. Ottosson, who has worked on such Hollywood blockbusters as “Spider-Man 2” (for which he received another Oscar nod), “2012” and “Men in Black 3,” relishes the chance to mine the tension even in less high-adrenalin environments.

“Compared to 'The Hurt Locker,' 'Zero Dark Thirty' felt to me like a much denser world in terms of the sonic space,” he says, “and the quiet or more-dialogue-driven scenes present as many challenges as the big action set pieces. It's interesting to work on a film that doesn't have an immense amount of action throughout. I've worked on so many that are nothing but action, and with those you kind of get to paint with all your colors – everything's jumping at the screen, so of course you made to make it cool and exciting. But when you're working on a long scene like the one at the compound, when they get Osama, it's 17 or 18 minutes in this really quiet place, with almost no music, and that really exposes a lot of things if you don't do them correctly. There's no give.”

In contrast to the blockbuster work, Ottosson describes his collaborations with Bigelow as heavily reliant on organic sound, even in the most high-octane sequences. “We used maybe even a little more than we did in 'The Hurt Locker,' and I built this film a bit differently, especially in the interiors.” Describing the principal locale of the narrative, Islamabad, as “a really dense city,” Ottosson was keenly attuned to incidental sound, tapping into the frayed nerves of the film's characters.

“If we were inside a building, we kept thinking, 'What's in the next building?' Or 'What's a block away?' And we kept going from there. We wanted the sound to emphasize the pressure that Maya is feeling: she's made this her life's mission, and not many people believe in her, so I think it helps to have this layered, sometimes overwhelming soundscape in the movie. But then in the interrogation scenes, we play it pretty stark: the guy's being tortured, but Maya is really uncomfortable too – really exposed, with nothing to hide behind.”

Ottosson prefers to play his explosions pretty stark, too – and he knows this terrain pretty well, having gained first-hand experience with explosives while serving in the Swedish military. It's knowledge that has served him well on both his collaborations with Bigelow.

“I was never in Iraq, but I remember how you think and feel in an environment like that,” he explains. “Every corner you turn, there could be something that could take you out. Or something behind you. So every time we cut, even if we're going somewhere in very close proximity to the previous shot, I thought it was important to establish an audible difference – to play with that perspective, make the spaces tighter. It takes a lot of work.”

In that regard, he describes the most challenging scene in the film as a chase sequence wherein Bin Laden's courier is pursued through a crowded market, with faces and voices accumulating to disorienting effect. “You could have just whizzed through it, but that's not how Kathryn works: with every cut, you're building something different, there's something else going by you.”

Once more, Ottosson found it easy to fuse the film's pared-down approach with his own experience and sensibility. “I've been around a lot of really big explosions, but the funny thing is, I don't ever remember hearing one of them,” he says. “When it hits you, the shockwaves travel faster than the sound. It shuts down your ears. I never thought, 'Oh wow, what a loud explosion'; I thought, 'Oh wow, I almost crapped my pants.' That explosion in the hotel [in 'Zero Dark Thirty'] – there's an insane amount of low end that hits you, which travels a bit slower, and I wanted to get the audience diving back in their seats with the terror of that low end, so that they feel like they're there, and not just in a loud movie.”

Alexandre Desplat's score – stylistically and structurally a very different affair from Marco Beltrami and Buck Sanders' work on “The Hurt Locker” – is sparely used, but Ottosson was at pains to ensure it was artfully integrated. “In 'The Hurt Locker,' a lot of the score was built out of sound effects, so that kind of made it easier to merge sound and music,” he explains. “Here, we wanted to achieve the same thing, even though we were working with stronger melodies, and a more traditional orchestral approach.

“Where we have score, I'd try to transition in from something else – maybe we'd have a jet flying by – to get you accustomed to it, instead of it just starting up out of nowhere, so the audience wouldn't overtly feel the music was trying to steer them. I think Alexandre did such a fantastic job, because he'll let the character feel what they want to feel, and then bring the music in a beat afterwards, rather than having it precede the emotion. It lets the actors be the lead the entire time. And that's typical of how we wanted to do things.”

Ottosson admires Bigelow's pursuit of realism in action filmmaking, describing her films as utterly singular – especially relative to his previous Hollywood projects. “All the regular tools I'd use on a blockbuster like '2012' don't work for her, because once you get this awareness of how cool something is, it takes you out of the movie. The idea with her is draw from the environment, to make it very natural, very real. With Kathryn's movies, it's back to basics. You don't want it too polished, or to feel like someone spent too much time on it.” He pauses, and laughs. “Of course, that takes longer!”