There's no sound when opening/closing door.
The missing sounds have quite a drawback in MP as you gain no audible confirmation of e.g. an enemy entering your building. It's also less atmospheric.
Sounds can be implemented via scripts executed when the animation triggers since OFP.
See this addon by Mondkalb for an implementation of (mp-synchronized) door sounds:
http://www.armaholic.com/page.php?id=19917 [^]