When children are unable to hear it can be very concerning for families. It is easier for children to match their parents emotions and that's also how they communicate emotions by facial expressions and actions.
It can sometimes be discouraging for parents to not be able to communicate to their child and can cause family dysfunction or disagreements.
It is important for parents to take part in the IEP process to determine what both teachers and parents can do to help their child learn and better communicate with those around them. As a teacher it is important to let parents know that you are there for them and are willing to do whatever it takes to help their child be a better learner and student. You as a teacher need to make it clear that you understand the frustration and want to help the parents to give their child a better, easier learning experience and to also help them when it comes to communicating at home and school.