This made for a week of hard-to-hear lecture.
I did talk to their instructor once, and he tried, but really, it was just too many firefighters talking simultaneously.
So the next day I got to class early and wrote the following on the board:
ATTENION: Medical students next door learning about the treatment of burns.
It may be in your best interest to make sure we can hear the lecture.
All of which was totally true. But that day the firefighters weren't in class.
Maybe it's for the best. :)