Children with profound or total hearing loss need auditory and visual cues to communicate, and they typically use sign language as their primary method of using and understanding speech. Learning sign language doesn't necessarily mean being unable to learn to talk. Using spoken language takes a lot of training, but it is not unusual that children with profound hearing loss learn both.
If you do decide to learn sign language, your child, you and the rest of your family need to be actively involved. Talk to your audiologist about what sign language method is best for your son or daughter, and talk with other parents, teachers and adults with hearing loss.
You may hear a lot of different opinions about sign language, so get as much information as possible before deciding what to do. Remember the goal of introducing sign language is to give your cild an effective means to communicate and express themselves.