It's also possible that with extended audio channels/speakers in an IMAX audio setup, the temp mix could have come out differently when 'upconverted' for that as opposed to a regular 5.1 or even stereo temp session to get this scene out there. If a regular theater has a 5.1 matrix, and an IMAX has something like a 13.x...a mix can be done specifically for the IMAX system instead of just letting it re-assign the 5.1 channels throughout. What can happen in some instances is that ambient noises or effects could get doubled into some speakers while the dialogue stays front center in lesser speakers...and you can get (surprise) something that sounds too noisy to hear dialogue. i.e. the surround/FX channels/sounds might have to be mixed 'softer' for IMAX because there's more speakers/channels to play them. So it could've come down to a rather quick temp mix that was fine for stereo and regular theater surround systems, but then didn't sound as good when 'translated' into IMAX systems....so they went back and did a quick remix optimized for IMAX sound systems.
