Jessica Chastain in "Zero Dark Thirty."

Sound designer/re-recording mixer Paul Ottosson creates the year's most complex and disturbing soundscape with "Zero Dark Thirty," easily surpassing his work on "The Hurt Locker," which earned him two Oscars. Indeed, his strategy of maximizing audience identification with the obsessive CIA officer, Maya, played by Jessica Chastain, brilliantly complements the narrative thrust of the acclaimed, if controversial, fact-based thriller about the decade-long hunt for Osama bin Laden.

Not only was Ottosson concerned with conveying authentically naturalistic sounds, but also ethereal ones as well that have more of a subliminal impact. Such was the case with the "enhanced interrogation" sequences involving waterboarding that have dominated and politicized the discussion of the movie.

"The waterboarding scenes are very naked and very sterile and it becomes harder to fill it up with lots of [sound] elements because you start thinking about the outside world," Ottosson contends. "It's more focused on what you see on the screen, which is horrifying."

As with "The Hurt Locker," Ottosson recorded sounds with the Erhu (a spike fiddle), courtesy of his wife, Karen Han, who is a virtuoso with the instrument. It's processed and distorted in a very unusual way yet plays organically. "There's a helicopter coming in before it starts," he adds. "The buildings rattle some and out of that I sneak in these other ethereal sounds that give us a natural in; then by the time the helicopter rattle dissipates, you don't know that it's already been introduced. There's only about an hour's worth of score [by Alexandre Desplat], so I use these ethereal sounds quite a bit. I needed ways of transitioning in and out without telling the audience that I was introducing something new and unreal. It's visceral and more of a dreadful feeling.

"I try to convey things from the person with the strongest point of view in the scene. And this is the first time that Maya witnesses the torture. She's disturbed by what she sees and so are we. But then she becomes so obsessed with the capture of bin Laden and even participates in the interrogation to obtain her goal. At that moment, I don't play these sounds anymore because, like us, she understands why we have to do this and it's not as appalling. I play up some of the outside sounds to show that she's in control and driving forward."