I wonder how well they can hear up there. I'd be terrified to do it unless I could see someone conducting me from the pipe organ, and then only if I were wearing earplugs. You... wonder if they can hear the organ, from inside the park? Why would you wonder that? I'm not a physicist, but sound travels slower than sight, and music especially does funny things in big spaces. There's more than one speaker in the stadium, and that wouldn't affect tempo anyway