Congo Jazz (1930)

Congo Jazz is a Looney Tunes cartoon starring Warner Bros.' first cartoon star, Bosko. The cartoon was released on September 1930. It was distributed by Warner Brothers and the Vitaphone Corporation. Congo Jazz was the first cartoon to feature Bosko's falsetto voice that he would use for the bulk of the series' run (the previous Bosko short, Sinkin' in the Bathtub, had used a stereotypical Negro dialect). It has the earliest instance of a trombone gobble in animation.

More at Wikipedia.