What characterizes the second stage in the three-stage evolution of cinema sound?
Adoption/Chaos due to competing systems like Vitaphone vs. Movietone
The evolution of cinema sound is described in three overlapping stages. The second stage, following the initial 'Invention' phase where basic synchronization was achieved, was characterized by 'Adoption/Chaos.' This period, primarily occurring in the late 1920s, saw intense commercial rivalry where major studios backed incompatible technologies, leading to a fragmented market. For instance, a theater showing a Vitaphone feature would have a completely different playback setup and expectation than one showing a Movietone feature. This conflict resulted in highly unpredictable audio experiences for audiences depending on where they viewed the film.

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The History of Sound at the Movies - YouTube