The answer is signing or sign language. As this is the expression or language that they use to communicate towards other people as they were not able to communicate using their tongues as they don't have any hearing or their hearing input is impaired.
While authoritative parents may expect high standards for their children, they also provide their children the resources and support to improve. This parenting style requires reasonable demands and a high level of sensitivity. Following decades of research, child development experts agree that the ideal parenting style is authoritative parenting. As per the question, Josh's mother shows a authoritative parenting style.