How did Pixar record two-year-old Mary Gibbs's lines as Boo?

Name: Monsters, Inc.
Released: 2001
Cast: John Goodman, Billy Crystal, Steve Buscemi

Question

Accepted Answer

Followed her round with a mic. She wouldn't stay put at the microphone, so director Pete Docter chased her around with one. Her dad was a Pixar story artist.

Monsters, Inc.

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