Profession can absolutely affect volume. Even without any hearing damage, any job that regularly requires that you project can become a habit.
I’m a chemistry professor at a community college, fairly well educated, and I flatter myself to say reasonably intelligent, but I still slip into what my wife calls my “teaching voice” in some social settings or even occasionally at home.
It’s not 40K, but I thoroughly enjoyed Mordheim: City of the Damned, despite some bugs and rough AI in places.