Jesus taught about those who could not hear him. Thomas answered and said to HIM, "My Lord and my God" because Jesus taught him, "He who has seen ME has seen the Father" and that he would know on this day that his Lord Jesus is in the Father his God.

In Jesus' eyes, the hearing impaired, and the deaf, are not people who can't physically hear audible sound, but those who cannot hear his voice. Blessed are those who hear Jesus.

Jesus is alive and well today. He is bodily risen in power and glory. His sheep hear his voice. But there are those who are not of the truth and they simply cannot hear him. They do not comprehend what he says in the Scriptures nor do they hear him by his Spirit which is in the hearts of those who love him.

Reference:
http://cad.ca/issues-positions/terminology/