Finally, thinking about you sitting there modulating the sounds and getting to a real soft part: there is an admonition in the Annex of SMTPE RP 141:2005
A.3 Too little noise in a theater or review room may be a problem as well as too much. With too much noise, detail is obscured and, ultimately, intelligibility suffers. With too little noise, intermittent intrusive noise may become audible and annoying; therefore, it is advisable to use reasonable background noise levels to mask intrusive noise sources
Well, let me emphasize that I usually adjust only once (and, as said, usually upwise), never back and forth between scenes or so.
'Modulating' is left solely to directors during premieres...
'Noise shaping'. Another interesting business model for the media block watermarking module companies. We need a feedback line from a very sensitive auditorium microphone to the media block. Or, towards the HVAC controller for legacy systems...
- Carsten