To accomodate special lighting fixtures a gaping hole was made in the ceiling over the stage. When the film crew left they also left the hole. For some reason it turned out that it helped improve the sound and Carnegie Hall never closed it even after the extensive renovations for its 100th Anniversary in 1991.
Very interesting comment. I enjoyed this motion picture. Not much of a movie (it has a minimalistic plot) but a wonderful collection of great compositions by great performers. I saw the movie yesterday but I did not notice "Mon couer s'ouvre a ta voix" (sung by Risa Stevens). By the way, if I'm not mistaken, Risa Steven is the singer who appears with Bing Crsoby in "Gong My Way" (El buen pastor).
"New Orleans" (with Arturo de Córdova) is another movie that is far from being a great film, but it contains a collection of great jazz musical performances.