My roommate stresses me out?

I know this sounds really ludicrous and weird but one of my roommate's is African, and his girlfriend stays over all the time who is also African, his room is next to mine and every night for about 20 minutes they shout at each other in their language and raise their voice to the extent that the whole house can hear it. But they're not arguing, it sounds like some sort of prayer or something, I don't know what it is because I can't understand it, but they speak really fast and loud and I don't understand what it is, it sounds like voodoo at first. I can't stand it, it interferes with my thinking, what should I do? If they're religious I can't exactly ask them to stop. What could it be? What can I do?