I grew up in a home where everyone talked very loud and shouts as well. It is very hard to get rid of the habit.
I came from a home that was quieter, more subdued. My wife came from a relatively loud family. When ever I go there I get a mild headache, because I am not used to what I think is shouting. One of the things that I have noticed is that her family never lets another person finish a sentence (I am probably exaggerating).
I also am a school teacher teaching 10 to 14 year old kids. When I get home it is hard for me to hear a lot of shouting and talking because I hear it enough at work.
1st. I grew up in the same but due to my father worked in a slaughterhouse and is somewhat hard of hearing.
and 2nd I to am somewhat hard of hearing due to working and I have the ringing sound in my ears can't hear as well as I used to, even though I am soft spoken I sometime have to shout at people.
I feel to say pray about it first ,then maybe go about a nice way to ask each person why so. It maybe to them a normal thing and don't realize their doing it or it maybe a medical problem ?