tissue in a deaf person become atrophied and our conclusions is that there was a mistake. that science had misunderstood the function of this tissue. >> reporter: the research also showed early exposure to a visual language like american sign language did not undermine a baby's ability to learn spoken language. in fact, petitto says, it's just the opposite. >> early exposure to sign language is by far the most healthy thing we can do for the human brain because the brain, the research shows us that the brain doesn't care about modality. it doesn't care if you give it the hands or the tongue. >> reporter: no matter how it's expressed, communication is really what language is all about. a little boy and his family were fully prepared for a life spent communicating through sign language. but a clinical trial is offering a second chance for deaf