There is a beautiful hearing-impaired actress named Marlee Matlin who won an Oscar for the poignant movie Children of a Lesser God. In the movie she consistently communicated via sign language, though her leading man knew she could speak. In a riveting scene near the film's conclusion, she finally verbalized in his presence. Her words were intelligible but not articulate, slowly formed just well enough to be understood, but not clearly. The character could not speak well because she could not hear.
Apparently such was the case for the man in Mark's story. Before Jesus unlocked his tongue, first he had to open his ears. Only when he had heard a message did he have anything to say.
So it is for most of us. We cannot share with others what we have not found ourselves. We cannot teach what we have not heard. We cannot articulate a truth to others that we have not appropriated in our own lives.