Have you explained to her about your mother? One of the things she is seeing is that you raise your voice to be heard and so she is doing the same. All the advice about whispering or speaking quietly is good. I have heard a class of noisy 6 year olds transformed because 'Miss has a bad throat'. You could try giving her permission to shout at your mum, but no-one else, so she has an outlet for her voice. I also used to tell children that I had a hearing problem and I couldn't hear them properly if they shouted. Once she realises that you ignore the shout but respond to a quiet voice she will adapt her behaviour.
The Republic of Ireland and their tensions with migrants.