The copy of the the three-minute talking short I viewed of the duet "Mit Mir So Spat" was dated as 1909 on the collection of German shorts I saw. Contrary to most peoples' understanding of film chronology, there were experiments in synchronizing sound and film as early as 1895; from 1906 through 1910, Deutsch Bioskop produced a series of three-minute musical films, which they showed at a dedicated theater in Berlin.
As with the others, the performers enter, take center stage, and sing. The primitive sound equipment made it impossible for them to move. This was a problem that would continue through the early Vitaphone period.
The difficulty of exhibiting such films, the long gap between these and the rise of the talkie era a couple of decades later and, indeed, the American-centric view of cinema has rendered these primitive efforts an obscure and largely technical backwater in film history.