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 opened 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…

Finally, they elected to use a scientific microscope that recorded in high frequencies to capture sounds that are inaudible to humans…

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…”

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?’”

When he recreated the sound effects for the film’s producer, Thomas Tull, he was so impressed he said audience members would need a trip to the drycleaners to clean their shorts!

Now that’s impressive.