Autism is considered a communication disability by many professionals. It is also characterized by a variety of other characteristics. Professionals who focus on communication specifically are focused on speech. It is thought that children with Autism would not have as many different behaviors if they were more skilled at using speech.
So how can parents help? One of the ways they can help is to do their best to make their child use what speech they have. If they only can make a sound when they want a specific item then they need to make that sound. If they can say some words they need to say those words at the right time.
Speech therapists have sometimes found that it is easier to teach children with Autism how to sign. One of the fears of parents have been if their child learns to sign they will not speak. Thankfully this does not seem to happen. Children who are going to speak seem to do it anyway.
Just the same as speaking though, if your child knows some signs for words they need to use them. If they say the word so much the better but if they do not insist on the sign.
This is more difficult than it seems because many times parents already know what their child wants. It is easier and faster to just give it to them. We have to resist that urge and remember the long term goals for our child.
Autism Medication: For Co-occurring Disorders