Sound mixer and sound editor may not be the most mysterious job titles on a movie crew. That dubious honor would have to go to gaffer and grip. Still, even among avid movie fans, few people fully understand the difference between the sound specialties.

But Erik Aadahl does. Aadahl has been nominated twice for an Oscar® for achievement in sound editing, for Argo and Transformers: Dark of the Moon. And he’s worked as a sound mixer. He says he thinks of the symbiotic relationship between sound mixing and sound editing in musical terms. The editors are like composers, creating the sounds, while the mixers are like conductors, taking the raw sounds and figuring out the best way to use and balance them: “More flutes here, timpani back off a little bit there.”

Practically speaking, a film’s sound comes together this way:

  • A production mixer records on-set sounds, including actor dialogue and background elements, such as sirens, a dog barking, or a lion’s roar.
  • Most films use some amount of ADR (which stands for either automated dialogue replacement or additional dialogue recording, depending on whom you ask), rerecording dialogue that wasn’t properly captured on the set, either because of background noise or because the director or actor wants to try a different way to deliver a line.
  • The sound editing team, meanwhile, works away from the set creating designed sound, which includes sonic effects like R2-D2’s language of trills, beeps, and whistles in Star Wars, or creative enhancements to existing sounds—amping the ferocity of a lion’s roar, say. Foley artists work in a studio creating classic sound effects—moving shoes in a box of gravel to recreate footsteps, for instance.
  • In the meantime, the composer is writing music for any scenes that need it and getting that music recorded.
  • A sound mixer’s job is to then mix those on-set recordings with the editors’ designed sounds and the music to create a beautiful—or scary, or tense, or sad—mosaic that becomes the movie’s soundtrack.