“Flow” does not have any dialogue — at least none outside of the sounds made by its ragtag team of animals escaping a seemingly Biblical flood — but it’s far from a silent film. The massive challenge and gift that director Gints Zilbalodis gave to sound designer Gurwal Coïc-Gallas was to provide that world as much weight, texture, and character as the animation does.

It meant starting early, not just on the environments but by having conversations about filmmaking that put Coïc-Gallas and Zilbalodis on the same cinematic page. “I asked [Zilbalodis] what were your favorite movies? What are you expecting for sound? All that was helpful for me to understand,” Coïc-Gallas told IndieWire.

The kind of movie Zilbalodis wanted to build was one where the audience could appreciate the spectacle while fully immersed in the action. This meant narrowing down the sheer amount of sounds in the world and strategically focusing...