There have been many times in my life, and still are occasionally, when I have not been able to understand the words coming out of the mouth of the person in front of me. Conversely, they have not been able to understand me. Once again, the communication barrier has been a source of never-ending frustration for myself and those around me.
I was talking with a father today who asked me if there was a moment of elucidation - a moment where language suddenly made sense to me. I told him there was not. It was, and continues to be, a bunch of gradual steps as I learn this language. But after reflection, I realize that was not quite accurate. There was a moment in my life that I did have a shift in my brain and suddenly language made sense to me. It happened when I was about 8 or so...I was in 3rd grade, whatever age that was.
My 3rd grade teacher was the first one who was able to get me interested in reading - mostly because we would get a free single-serve pizza at PizzaHut if we read the most books. Pizza was my favorite food at that phase in my life (I still really, really like it - but there are too many good foods to call pizza my favorite now. However, I would never want to imagine a world without a good pizza, that would just be sad. Anyhow.). I was definitely motivated to get that pizza. I read and read and read. I have no idea how many books I read, but I won the pizza, I remember that.
The point is that it was shortly around that time that my shift took place. My theory is that I experienced something very much like what a NT person experiences when learning a second language. Those who really become fluent in a language all have described a moment when they suddenly found themselves speaking the language. They began to think and dream in that language. That is when it really became something more than just words they were speaking and hoping they were getting the intent of the words correct.
Listening to people speak, I could understand a word here and there, but the majority of the language was "foreign" to me. People would speak so quickly and my brain just couldn't process their words that fast. But reading was a different matter. I could read at my own speed and stay on one sentence until I understood it's meaning fully. This was the turning point for me.
So what if your child does not read? Speak slowly. Let each word be heard individually and pause to allow the meaning to hit before you move on to the next thought or sentence. Enunciate every consonant so that his brain can spell out the word in his head. This will help dramatically. There also seems to be some sort of auditory issue, although I have aced every hearing test I've ever taken. Again I have a theory about it, but it is just my theory.
It seems that my sensitivities to the non-verbal world are so loud that I sometimes feel like a person is speaking even when they aren't. Or I am literally hearing their heart while different words are coming out of their mouth. I have, whether by intent or by some other design, learned to shut off the auditory and pick up on the heart. So when someone is speaking to me, it is sometimes hard for me to shut off listening with the heart enough to be able to hear the auditory. Does that make sense? So sometimes the emotions coming out of a person are so strong that I cannot hear their words. I'm learning to be better at hearing words and not just emotions.
Back to the comprehension of the words. It was shortly after I read all of those books that things began to "click" for me. I can't say I understood everyone and everything, but I moved from being able to put together a few words that had meaning to comprehension of the meaning of those words. This shift is what really allowed my language skills to grow.
After that shift, the verbal visualizations were the most helpful thing to increase my comprehension of the language. When I heard a word that I did not understand, I had no idea how to figure out what it meant. But describing an emotional connection to a word helps me a lot. So if you want me to understand what beautiful means, paint me a verbal picture. I would watch for the next time a look of wonder and joy comes across your child's face as he is watching a sunset, or watching a butterfly, or looking at the way his foot leaves a print in the freshly fallen snow. Then, when we are in a situation that calls for that emotion, I would recall to him the feeling he had in that moment that the sky went ablaze with color. Suddenly the word "beautiful" has an emotional experience attached to it. Now I comprehend the meaning of the word because you used my language to describe it to me; namely, the language of the heart, of feelings.
I still have words I do not understand or misunderstand the meaning when people use them. I still hear the heart far more than I hear the mouth. But, for English being my second language, I think I do pretty well. :)
So, I've kind of just been meandering through my thoughts here. I hope the feeling of what I am trying to convey is clear. Speak more slowly. Read more often. Seeing the words spelled out in front of me increases my comprehension by about 45%, maybe even a little more. If he can read, write down things that are really important and that you want to be sure he will comprehend. Then if he does not understand a word, encourage him to ask about it. Don't be frustrated about his learning. It may seem tedious, but he is building one massive vocabulary in a foreign language. No matter what your language is, verbal communication is a foreign language for him. It is as easy for him to learn to communicate verbally as it is for you to learn to communicate with just your heart and no words.
Middle ground? You learn to open your heart as he is learning to use his tongue. Then the gap is bridged that much more and the two of you will find conversations going back and forth between the mouth and the heart, not even noticing that you are slipping between the languages as effortlessly as you slip between breathing and blinking.