score:9
When visiting another country and their museums, you should/must follow the local customs and regulations.
One should always be respectful of the others; If you feel someone is not respectful, then notify the museum staff; they will handle the situation themselves; do NOT put yourself in a position of confrontation.
IMO, some of the rules that should be applied to museums (*):
(*) Art museum should be considered more stringent in the application of the rules while science museum will probably be less (especially in noise level).