My colleague will often yell at his students. His room is next to mine, and we can hear his yelling through the wall. It's not like he raises his voice or speaks firmly; he screams at the top of his lungs. I've never screamed at my students, and I think that's one of the reasons I rarely have problems with them. He refuses, however, to accept my advice that screaming is a terrible option and that his students are just worse than mine. His students walk over him and ignore most of what he says. How can I convince him otherwise (if it's even my place to do so)?