This post is wrong, wrong, wrong. As noted on Wikipedia,
"Unlike the Disney shorts, in which Oswald did not speak, Lantz's cartoons began to feature actual dialogue for Oswald, although most of the cartoons were still silent to begin with. Animator Bill Nolan did the voice of Oswald in Cold Turkey, the first Lantz cartoon with dialogue, and the following year Pinto Colvig, who was working as an animator and gag man at the studio, started voicing Oswald. When Colvig left the studio in 1931, Mickey Rooney took over the voicing of Oswald until early in the following year. Starting in 1932, Lantz ceased to use a regular voice actor for Oswald, and many studio staff members (including Lantz himself) would take turns in voicing the character over the years. June Foray provided Oswald's voice in The Egg Cracker Suite, which was the final theatrical short to feature the character."
SUCK IT BOING BOING.