I'm apologising in advance - this is a long post. I feel justified, however, because we've been where you are, Dara - twice/three times already. And I think we can now claim a fair amount of success.
Dara, you have the wrong mindset for this, that is why you are having so many problems here. Please be aware - I'm not meaning this as criticism, merely an observation. It's very hard to be otherwise, when you've not had access to anything sufficient to help your understanding of what is going on here. If anything, you're being told stuff that is making you MISunderstand even more (ie the language reports - I'll talk about that further on). You're also a trained teacher, and I suspect your training may be also misleading you. These kids are different, they need to be handled differently. Throw out the rule book, throw out everything you've been taught, and just stop, and watch him. Try to get inside his head. What is he doing now? Why do you think he is doing it? There is always a reason, one that makes sense to the child. What do you think he will do next? Why do you think he is doing it? How important is it to him?
For example, you said, "He hears us he is choosing not to listen or respond". Think about this, objectively. How do you know he hears? How do you know his lack of response is choice? How do you know his 'choice' is not valid? Remember, he is only 3, for him the world exists only to do his bidding (it's how most babies and toddlers think) and he hasn't yet learned the value of compliance.
And you've been trying to teach him this, by punishing him when his behaviour is unacceptable. But this is clearly not working. And with any discipline method, when it's not working, then you shouldn't do it. There is no point and in fact you can be making more confusion, more work for yourself, by persisting.
With Pervasive Developmental Disorder (PDD), "SuperNanny" techniques generally have to go out the window. These kids think differently, their values are different and you need to go to where the child is, met them there and work back. You can never force the child to go to you (figuratively) - you have to go to the child.
Read "Son Rise" if you can, at least the first few chapters. The child in that book was more profoundly withdrawn and autistic than your son may seem to be (I base this on the reports of your son's language ability) but the same techniques are probably needed.
There are a lot of things in Sammy, that I see in my own kids (apart from easy child). The noises, especially. He is NOT doing this to annoy you. I remember having this battle with difficult child 1 when he was 6. We have it on record - we were on holiday in Greece, I was videotaping as we drove through Greek countryside. This was a wonderful opportunity for the kids to experience a foreign country, I strongly believe in learning at every chance. But instead of paying attention, difficult child 1 sat in the back of the car making his "WWIII" noises, as we called them. No matter how I scolded, how often I said, "Be quiet or your noises will come out on this tape!" he would not stop it. I got very angry with him, day after day. And day after day, the noises persisted. The irony of it all - HIS noises did not come out on the video. My scolding did, and it spoils the tape! He also remembered a lot more of that trip than I realised.
The noises - we had to learn to live with it. difficult child 3 does the same thing (different noises, though). The noises do change as the child gets older. They learn what is not acceptable and eventually find vocal stims which are less obvious. difficult child 3's currently sounds like a quiet growl in the back of his throat, as if he is clearing his throat. difficult child 1's sounds like a male emu calling his chicks.
You cannot and should not try to punish what the child cannot help. If you stand over them, they will control it - as best they can. But it will break out, one way or another. There is so much in their lives, in their heads, that is out of their complete control, that whatever they CAN control, they try to. This is another source of conflict - he will want to control his environment as much as he can. He will be objecting to change, especially change without warning. Trying to get him to stop playing with his trucks and go get dressed - tantrum. trying to get him to stop watching a video over and over, and go have his bath - tantrum. And so it goes. Interacting with others - other kids cannot be controlled, and this causes problems. Other kids want to exert their own control, or bring about their own unpredictable changes - again, problems.
I stress - these are things in him you cannot change, not right now. Maybe later, when you've got him further down the track. Maybe by the time he is near his teens. That's when other kids stop being so egocentric and start thinking a bit more about consequences of their actions on other people (then they stop thinking about it all, for another few years!).
You say your biggest problem right now is the defiance. Yep, I can see that. Know it well. There are ways to handle this, but if you try, at any time, to meet the irresistible force with the immovable object, you will lose, because he is always going to be stronger than you. I'm not kidding.
What you have to do, is get around him in other ways. Think - what is your main objective? To teach him obedience? or to get him to do what you want? They are NOT the same thing.
What you need to do, to get him to do what you want, is to convince him that HE wants to do it, too. You need to give him time to make a change in what he is doing and you need to motivate him to make that change.
I will give you an example with difficult child 3 - from last night. We had come home from shopping and the first thing difficult child 3 did (as always) was go to his computer games. Now, difficult child 3 has chores (we've worked our way up to this, remember). I was able to say, "difficult child 3, it's getting dark soon. I need you to let the hens out and change the water in their water bowls. Please do this at the next logical break in your game."
I know if I had said, "Go change the hens' water NOW!" I would have got defiance and a shrieking rage from him. But by saying it the way I did, I got what I wanted, and he got what he wanted. And the hens got what THEY wanted, too.
Later on, when I needed the evening routine to move along, I said to him, "difficult child 3, you need to go have your shower. If you go now, your dinner will be ready for you when you come out. if you delay much longer, your dinner will get cold."
He needed a reason, he needed a NATURAL consequence and I got instant compliance.
Our Pervasive Developmental Disorder (PDD) kids need to understand WHY they need to do something. They are naturally obedient, but within their own framework. You may try to teach them the rules, but the rules the Pervasive Developmental Disorder (PDD) kids will learn are the ones they extrapolate for themselves, based on actual observations. For example, in school we constantly said to difficult child 3, "Do not hit other children." We made him repeat it after us, we made him write it down. We wrote it for him and left it in his pocket, along with other rules. But what he OBSERVED was very different - he observed other kids hitting (often hitting him) but did not realise they were only doing this when there was no adult to see. I his mind, other kids could hit and not get into trouble. Only difficult child 3 would get into trouble. So in difficult child 3's mind, the rule was, "Other kids will hit difficult child 3. Then difficult child 3 will get into trouble and be put on detention, probably because that's the way things just have to happen, for difficult child 3."
An example of how they need to understand in their own way - difficult child 3, with difficult child 1 & easy child 2/difficult child 2, were involved in an important scene in the feature film, "The Black Balloon." Amazingly, difficult child 3 had been chosen to start off the scene (a school stage production of Noah's Ark) with one line. This meant he had to stand on the stage where he was told and deliver the line. He had been coached to say the line at the right speed and clearly. The rehearsals for the whole scene took three months, once a week.
On the day of filming - difficult child 3 stood on the stage and delivered his line. Then he got down again. "I did it right, it's only one line," he said. Now, even though they had hired someone as "difficult child 3 wrangler" (and also to wrangle the other Pervasive Developmental Disorder (PDD) kids in the cast) this person just wasn't handling him right. She tried to cajole. She pleaded. I finally said, "Let me talk to him." (thankfully, the director was busy and hadn't yet noticed we had a problem).
What I had to say to difficult child 3 - "Honey, you did that line just right. Yes, you know you got it right. And the other people who were doing their jobs - nobody stuffed up, there is nobody to be angry with. But there are good reasons why they need you to do it again. When you delivered the line, the lights were in the middle and high up and the microphones were on the left. They need to do it again, with the lights on the left and the microphones on the left still. Then they need to move the microphone. Then they will need to move the lights again. The cameraman needs to do it with his camera still. Then with the camera moving. Then with the camera still, but on the right. Then maybe the sound guy will need to record the line again because a plane flew overhead.
Honey, there are many reasons and the director is the boss of it all. He knows exactly what he wants and he won't make you do any more than he absolutely needs you to. They just need to do this over and over, lots of times, because each time they need to make a little change in everything else, so they've got as much as possible from as many different angles as possible. That way when they put it all together, they will have more than enough to choose from. OK?"
difficult child 3 was now fine. He waited for his cue, got back up on the stage as and when directed and performed like a pro. He was right on cue for each take, over the next couple of hours. No questions, no whining, because he now finally understood. Meanwhile he watched the cameras move, the lights change position, the sound guy in his booth and finally understood.
That is what you can have, when you give your child the chance to understand WHY.
When your child is only three, his ability to understand at that level is very limited. His frustration level is very high and most of the raging (if not all) will be his response to frustration and sometimes fear. The more things escalate to raging, the bigger the problems. At first we would find that after the first rage of the day, the rest of the day was a write-off. After a while, as difficult child 3 saw that we were trying to help him stay in control, he began to start his good day over, each time he calmed down.
The screaming, the tantrums - these are not acceptable. But they are understandable. We stopped punishing for the rudeness, for the noises, for any raging that was clearly the result of frustration. That doesn't mean we condoned it - far from it. But we ignored it, then continued to move on. Part of ignoring it means removing yourself from harm. If he's kicking you, move away. If he follows and this is a routine problem, either put yourself in your room, or set up a playpen or other barricade, and get on the other side of it so Sammy can't reach you to kick. If possible, find another way for him to vent physically - a swing, a hammock, a trampoline.
Sammy's language now tests as normal, but I bet it's not, not right at the fundamental day-to-day basis. I remember when difficult child 3 finally tested as having language in the normal range. I think he was 7 or 8. He's STILL not 'normal' in his interactions and in the way his mind manipulates language. In some areas he's superior. In other areas, he's very literal.
Language testing is a blunt tool. It can only tell you things in large. You're going to be living with the fine detail problems for years.
Sammy may take longer to process what he hears, for example. He will take even longer if he's concentrating on something else. If he's concentrating so hard that he has shut out all other sound, he won't hear you at all - not consciously. And yet he would hear a chocolate bar being unwrapped in the next room.
This is normal, for Pervasive Developmental Disorder (PDD) kids. Even for severe ADHD kids. It is not disobedience and shouldn't be punished. Instead, to get the attention of a Pervasive Developmental Disorder (PDD) kid, you should make sure you have eye contact. be gentle about it, because sometimes a touch on the shoulder can startle them into a rage. It will depend on what he is doing.
Watch him, Observe. Go back to your teacher training and treat him as your own case study. But you will handle him best, if you consider him to be an alien changeling who you need to understand in order to more effectively interact with.
Somewhere in there you have a beautiful, loving, bright child who will bring you delight. Inside he wants to fit in, he wants to please you, but sometimes it's all just too hard, there is just too much to try to do, a lot of which he just can't manage just yet.
He will get there, but he needs you to meet him where he is and slowly show him the way.
Marg