Beanie, I found this and it sounds exactly like your son.
The Boy Who Stopped Talking:
http://discovermagazine.com/2006/apr/vital-signs
From the article,
"About 25 percent of children with autism develop language normally but then lose the ability to speak sometime between 16 and 30 months of age. The condition, called regressive autism, is not known to many physicians, so they may worry about a rare degenerative disorder instead."
He makes lots of different noises and alot of the time it sounds like he is talking to himself when he babbles but he doesn't say any words anymore. Before he start walking he could say about 10 words and then when he started walking he just quit talking it was like he thought why do I have say it when I can just go get it myself.
It's good that you are having him thoroughly checked out, if only for peace of mind. I'm sure this is very worrisome for you! Does he make any verbal noises at all??
His hearing has been checked and the doctor said it was fine. We actually just had to go and get some blood work done today. We had an appointment with a neurologist a couple of weeks ago and they want him to have an MRI done to see if there is anything there. He is a very aware of what is going on around him, and I know that he understands what I am saying to him because for the most part he listens when I tell him something, but sometimes it seems like he is just ignoring me and he doesn't say anything.
Have you had his hearing checked? I think he needs a complete work-up by a child psychologist, and they can determine if he has any sensory disorders and how to treat them. Eleven months old is very young to be talking, make sure you encourage him to use his words. When you give him something, say what it is and try once or twice to get him to say it.