How do children hear anger?
Even if they don't understand the words, infants react to the way their mother speaks and the emotions conveyed through speech. What exactly they react to and how has yet to be fully deciphered, but could have significant impact on a child's development. Researchers in acoustics and psychology teamed up to better define and study this impact. Ref. Source 4y.
Your experiences as a child has to be some of the best if you're going to turn out okay as an adult. If all you remember of your parents was them being angry then you might do the same with your own child or have some kind of psychological problems.