Leopold Stokowski recorded the classical music in the film at the Philadelphia Academy of Music, using the Philadelphia Orchestra (of which he was still principal guest conductor), on a multi-channel sound system, the first time one was ever used to record music in a film. The musicians seen in the film, however, were L.A.-based players doing what was called "sideline" (seen but not heard, merely miming to a prerecorded soundtrack played by others).
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