Perhaps the worst aspect of deafness is not the inability to hear. Deaf people say they can overcome that with hearing aids, cochlear implants and other technology, and can still communicate using sign language, gestures, writing notes, lip reading, and such simple things as acting out an idea or pointing to something.
For many, many deaf people the worst part of deafness is isolation. They are excluded from all that is going on around them because they do not share a common language with their society.
Here in Cambodia our deaf students do not know sign language when they come to us and their families almost never learn sign language. When our students are at home with their hearing parents and brothers and sisters, they are isolated. They may be in the same house, may eat together, but the deaf person has no communication.
Many young deaf people come to us at age 19-23 and they have never spoken to a human being in any language. All the things hearing children learn from hearing parents as they grow up, the deaf students have missed.
That is why it is so important for more hearing people to learn sign language. Then when they encounter deaf people at work or in a group or socially or just on the street, they can communicate and can include the deaf person in what is happening.
That is why the Deaf Development Programme teaches regular sign language classes.