When the filmmakers of Godzilla—the original Godzilla, released in 1954—were creating the creature that would become an icon, they were creating something else, too: the sound that would give their new monster his distinctive roar. This was harder than it seemed, given both the demands of the task and the technology of the time.

At first, they tried to use recordings of animal sounds to get the beast's distinctive shriek; Godzilla is more than a mere animal, though, and nothing quite captured the shriek they wanted to achieve. Finally, the filmmakers enlisted the help of the composer Akira Ifukube, who used his preferred tools—musical instruments—to create the beast's bellow.

Ifukube and his team realized that friction would be the key to making a noise that would roar in the required way. So they coated a leather glove in tar resin and then rubbed it along the string of a double bass. (Think nails-on-a-blackboard, but lower-pitched.)

Since then, NPR notes, there have been pretty much as many Godzilla Shrieks as there have been Godzillas. Godzilla Raids Again, from 1955, has its own signature shout. So does Godzilla's Revenge (1969). As does 1998's Godzilla.

The version of the film—and the version of the eponymous monster—that hit theaters this weekend is no different. Godzilla, 2014's, has its own unique roar, one that, like its previous incarnations, takes advantage of the latest technologies to do its particular take on shrieking. The pair that worked on the latest roar, the sound designers Ethan van der Ryn and Erik Aadahl, spent about six months creating a roar that would befit the latest Godzilla. Like Ifukube before them, they first experimented with friction-making strategies—things involving acoustic aids like rusty car doors and human palms rubbed against a tom-tom.