Like Icarus, it’s always possible for movie sound design to fly too close to the sun; too many audio layers and the sound of a moment can start to melt into a mess of nothing. So the filmmakers behind “Kpop Demon Hunters” — in addition to working so diligently on turning the film’s musical numbers into true bops — started working with supervising sound editor and re-recording mixer Michael Babcock very early, before animation had even begun.
Babcock and directors Chris Appelhans and Maggie Kang wanted to start figuring out the demonic voices for the evil boy band Saja Boys and for how HUNTR/X lead singer Rumi (Arden Cho) would express herself in moments of stress. This meant Babcock, who has a musician’s background himself, went to work studying the sound of K-pop and of pop music generally, in order to find out the right sonic approaches that would be fantastic and transporting, but still live inside the film’s musical language.
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“K-pop music is very intricate and has a certain polished sound to it,” Babcock told IndieWire. “So it really gave me the excuse to listen to a bunch of different K-pop music and pop music.” Getting the demon sound led Babcock to different ways of processing vocals, from computer voices to Billie Eilish and Imogen Heap.
“I took a lot of treatments, the jumping off points they use — everything from reverbs to how they layer voices, how they all do the harmony because, I mean, harmony is a big theme in the whole movie,” Babcock said. “The [demon voices] have a very specific treatment on it, a combination of reverb delays and coursing type things, which are all production tricks actually used in K-pop.”
The sound of K-pop also hums through the other magical elements of the film, especially HUNTR/X’s weapons and the strange familiars that Rumi and Ji-noo (Ahn Hyo-seop) use to communicate with each other across enemy lines. The key for Babcock was to make sure, in each sequence, especially the more action-packed ones, that the sound effects were pitched to the songs.
“They’re in the beat. If there are any kind of hits, anywhere in any of the songs, they’re to the beat. So that’s a lot of fun. But also finding an organic way to do that and not take away from those great songs — for example, the swords, I’m super proud of them. I didn’t want them to sound too processed, for them to have some organic genesis to them, so I went on Amazon and bought a bunch of tuning forks, and we manipulated those. They kind of sound like swords when they resonate.”
One of the trickier elements to sound design on “KPop Demon Hunters” was actually the cutest, most unassuming one. The mysterious spirit animal messengers that Ji-noo sends, a tiger and a magpie who represent the nobles and commoners of many Korean folk tales, needed to be otherworldly without being fully demonic. Especially if the tiger and the magpie have a name among the crew like Derpy and Sussie.
“Particularly Derpy — they never say the name, but Derpy was a combination. You can’t make that creature too scary. There’s a cuteness to how it was animated. So it’s actually harder on the sound design side to make something cute than it is [to make it] scary. A lot of Derpy is animal sounds layered with me manipulating my voice to be able to get the character to emote.”
Emotion was the throughline for every sequence in “Kpop Demon Hunters,” which is part of why Babcock found the work so satisfying. “This movie had some of the most challenging scenes, sonically, I’ve ever worked on,” Babcock said. “Being able to be rhythmic with certain things and be very strategic with sounds — the whole end of the movie, from the Saja Boys doing ‘My idol’ to the finale, that’s one of the most fun, intensely wonderful, emotional things I’ve ever mixed in my career.”
As with music, doing that work and sneaking in so much sound is all about the beats and the pitch. “There’s actually more sound design than I thought we’d get away with, and it doesn’t sound different than how you’d hear the songs on the album,” Babcock said. “ It’s a combination of being exactly precise and, frankly, tasteful, between the music and anything else going on.”
