If you're obsessed with movies like I am, you're gonna geek out over this.
Jimmy MacDonald was a sound effects artist, animator, voice actor, musician, and the original head of the Disney sound effects department. He was also the voice of Mickey Mouse from 1948 to 1976.
He was on the Late Show with David Letterman back in the 1980s to show how he did sound effects for Disney movies! The one for the seven dwarves walking is GENIUS.