Sound designer Erik Aadahl has worked with some pretty intimidating on-screen characters in his film career, from transforming robots to muscle-bound superheroes like Superman and Daredevil to big, green animated ogres.
This time, Aadahl had to handle a real monster: Godzilla. He was hired to update the creature’s run-for-your-life bellow three years ago, before the latest update of the 1954 monster movie had been green-lit for production. It opens in theaters nationwide Friday.
“It’s one of the most famous sound effects in cinema history,” said Aadahl. “We really wanted to embrace that and use the original as our template, and pay homage to that.”
The original film’s composer, Akira Ifukube, used a double bass, a leather glove and some pine tar to produce Godzilla’s trademark call.
“They’d rub the glove against the double base to create that groan,” Aadahl said.
Aadahl sought a fuller sound (to take advantage of contemporary theater sound systems), but wanted to retain the same musical key of Godzilla’s iconic roar. He and supervising sound editor Ethan Van der Ryn recorded hundreds of sounds with the same qualities and timbres as the original.
They started recording animals: Elephants, dolphins and anything with a shriek — “nothing quite felt right,” Aadahl said. He and Van der Ryn moved on to inanimate objects that made shrill sounds: Ironing boards, rusty car doors.
Finally, they elected to use a scientific microscope that recorded in high frequencies to capture sounds that are inaudible to humans.
“There’s this whole invisible universe of sound that we do not perceive, we cannot perceive,” Aadahl said. “But we can record those high frequencies, then slow them down so they come into our human range of perception.”
Aadahl won’t say what sound, exactly, he recorded to capture Godzilla’s iconic roar, which he broke into two parts: The cathartic shriek and the rumbling, almost melancholic, finish. Whatever it was, it required a thousand different takes before Aadahl arrived at what he called “the winner.”
“It’s not an intellectual thing, it’s a very gut-level thing,” Aadahl said. “For me, my temperature gauge is the hairs on my arm. If I start to get goosebumps, I know I’m going in the right direction. If I can get the hairs standing up the straightest I can, that’s what I go by.”
The duo recorded the sound reverberating in real-world environments.
To authentically recreate the sound wave rolling through an urban environment, Aadahl and Van der Ryn set up a 12-foot-high, boulevard-wide sound system (an old Rolling Stones’ 100,000-watt speaker system) on the Warner Bros. studio lot in Burbank, and spent the next five hours on a Saturday afternoon recording the distinctive roar from inside parked cars, behind office windows and on top of buildings.
“We were getting calls from across town, from Universal Studios,” Aadahl said. “The tourists wanted to know, ‘What’s happening down there?'”
Aadahl said he screened Godzilla’s roar for producer Thomas Tull, of Legendary Pictures, on a sound stage.
“He swiveled around to me with this serious expression — this is a make-or-break moment — and he said, ‘People are going to be blown away,'” Aadahl recalled.
It’s actually a G-rated account of Tull’s reaction, in which he suggested audience members would require a trip to the dry cleaner upon hearing Godzilla for the first time.
This article originally appeared on Recode.net.