Why no ADR was required for Oscar-winning sound in The Zone Of Interest

At the 96th Academy Awards ceremony, The Zone of Interest won Best Sound, which was accepted by production sound mixer Tarn Willers and sound engineer and designer, Johnnie Burn. Here, Willers explains how the audio team captured Oscar-winning sound for a director that asked its actors to embrace acting as if they were not in a film.

The Zone of Interest is a historical drama film written and directed by Jonathan Glazer, co-produced between the UK and Poland. Starring Christian Friedel and Sandra Hüller as the Nazi commandant Rudolf Höss and his wife Hedwig, it focuses on the pair as they strive to build a dream life for their family in a home in the ‘zone of interest’ – which just so happens to be next to the Auschwitz concentration camp.

Glazer opted against visually portraying the atrocities within the concentration camp, preferring that they be conveyed through sound alone. He has referred to the film's sound as "the other film" and, arguably, the core of the film.

In pursuit of this vision, Burn meticulously assembled a 600-page dossier comprising pertinent events at Auschwitz, witness testimonies and a comprehensive map of the camp to accurately gauge distances and echoes of sounds. Burn dedicated a year to crafting a sound library, encompassing noises from manufacturing machinery, crematoria, furnaces, boots and period-authentic gunfire. 

The sounds emanating from behind the camp walls include the piercing screams of prisoners, the aggressive shouts of guards, and the ominous reverberation of the gas chambers and crematorium – all set as an ominous backdrop to mundane, everyday events taking place within a manicured residence within sight of the camp’s chimneys.

Jonathan Glazer wanted the actors to exist entirely inside a world, with no evidence of film paraphernalia in sight.

Glazer insisted on an immersive set in which the actors scarcely knew they were in a film, which presented mixing lead Willers and his department with unprecedented challenges. 

“Jonathan Glazer wanted the actors to exist entirely inside a world, with no evidence of film paraphernalia in sight,” he explains. “We had 10 cameras hidden in the main house. The actors improvised a great deal. They didn’t have marks. The dog was real, the baby was real, and if one of them did something unpredictable, the actors were directed to respond as one would in real life. 

"As much as possible, he wanted the actors not to feel like they were making a movie. I had to get great range and clarity on two floors, through thick concrete walls and across the outdoor garden. The house was live, with no one except the actors allowed in during shooting. So, no boom operators. We could not have RF or dropout issues, period, because we couldn’t just run in and check things. Much of the time, the actors didn’t know where the cameras were. Sound from every source had to be flawless, all the time.”

Willers relied on Lectrosonics wireless kit to capture what was needed, using SMB, SMDB and HMa transmitters as well as SRb receivers mounted in an Octopack multi-coupler. Indeed, Willers and re-recording mixer Burn depended heavily on wireless:

“We had radio mics on the actors, plus several plant mics placed strategically throughout the house and garden,” he recalls. “I used SMB and SMDB transmitters. I also had HMa transmitters for the plant mics. My SRb receivers are mounted in an Octopack. Just over the garden wall was a container dressed to look like a guard shack. Inside that shack were me with my receivers, Jonathan with his monitors, and the video playback.”

Much of the time, the actors didn’t know where the cameras were. Sound from every source had to be flawless, all the time.

Within this matrix of microphones, actors would sometimes do long walk-and-talks. “For example,” says Willers, “from the bedroom down the stairs, through the kitchen and out into the garden.” When asked if he consistently received clear audio free of dropouts or interference, Willers’ answer was simple: “Yes, the setup worked. It had to.”

Though much of the film’s scenes involved interiors, a scene involving a family canoe excursion tested Lectrosonics’ reputation for durability under adverse conditions.

“We shot that scene on a scorching hot day, as was scripted. It was also scripted that a storm would hit and made them return home,” he recalls. “Lo and behold, an actual monsoon-like rain occurred, so I suppose creatively speaking, the weather gods were with us! The kids and Christian were just wearing vests, and I had been directed that at any point, one or more of them might jump into the river to push the canoe. So, no body packs were used.”

No ADR was needed for audio or technical reasons; What you hear in the cinema is the actors speaking on set.

Instead, Willers placed his SMBs closer to water than any other mixer would perhaps dare tell a rental house about. “Around the inside rim of the canoe, there’s a lip just wide enough to hide assets,” he shares. 

“I planted five mics on SMB transmitters. Aqua-packs would’ve been seen, so I wrapped them in cling film. Even though a little bit of water got through, the transmitters performed all the way through the sequence with no issues whatsoever. Some of the mics were casualties of war, but the transmitters lived.”

The ultimate proof of Willers’ and Lectrosonics’ wireless mettle was the near absence of any automatic dialogue replacement (ADR) in the entire film. “No ADR was needed for audio or technical reasons,” he nods. “There might have been a couple of lines added creatively, but that was it. What you hear in the cinema is the actors speaking on set.”

Zone of Interest image credits: Courtesy of A24