Here's a somewhat obscure (but still quite interesting) animated short from 1929. Finding his Voice is the saga of Talkie and Mutie, a pair of anthropomorphous rolls of film. As you might have guessed from their names, Talkie is a talking picture, and Mutie is a silent picture. Mutie wants to know how Talkie got his voice. Talkie explains that a certain Dr. Western (who is, by the by, a thinly-veiled metaphor for Western Electric, who commissioned the film) gave him his voice, and takes Mutie to see the good doctor.
Finding his Voice is interesting for several reasons. First and foremost, it offers the viewer a glance into the technical niceties of the Western Electric sound-on-film process, which was widely used by the Fox Films Corporation in the late 20s and 30s (mind you that this is long before Rupert Murdoch took over and Fox became the mouthpiece of the Antichrist). The sound-on-film process, by the look of it, was downright Byzantine in its intricacy and obsolescence, and--from what I understand--allowed for a somewhat inferior sound quality to the Vitaphone process used by Warner Brothers (it is ironic that the sound in Finding his Voice was apparently recorded via the Vitaphone process).
From a less technical perspective, Finding his Voice also merits attention by virtue of its being one of Max Fleischer's earliest post-Disney efforts, antedating Betty Boop even in her earliest, canine form by about a year or so.
One final detail--the tune which plays at the beginning of the film is, appropriately enough, "Ever Since the Movies Learned to Talk". A bit more information about the song (and even a recording of the song itself!) can be found at Vitaphone Varieties.