THE JAZZ SINGER might best be called part-talking. There was a Vitaphone soundtrack of background music, occasional sound effects, some dubbed singing, and "live", or better yet, synchronized singing and some dialogue. I don't think there was any intent at the outset to make it all-talking. Jolson's next film THE SINGING FOOL had more dialogue, but still included silent sequences. LIGHTS OF NEW YORK makes a better claim to being "all-talking".
That's very interesting. Thank you for the information.
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