yep, sounds very familiar :)
this one time there was this central African lady who pulled out all the stops both in volume and in length, she even decided to have an argument with the conductor :x
but most go silent... I usually let them polite-but-firmly know this is a silent compartment (pointing to the signs on the windows) and that they can continue their conversation in the vestibule (also pointing to the door), that almost always does the trick
I guess I have a very stern look :)