Welcome to the crowd!
* If his attention span is really short, have many short reading sessions. See if you can get him to point.
* This was the most frustrating this for me when DS started therapy just before turning two: they said he couldn't understand complex sentences, so talk simply. That didn't help, so I was to only say four words or less to him at a time. After a month or so of this, he looked interested, but not understanding. Finally, the hard part: I could only say one word to him at a time. I felt like I was treating him like a dog (and so did strangers who glared at me): "Come!" "Sit!" "Drink!" "Shoe!"
But it worked!
* DS couldn't make his mouth into an "o." It was the weirdest thing, but I guess it's pretty common with this condition. We were to take him to Wendy's and have him eat the frosty with a straw. (Getting a straw with through the drive-through was interesting, too. "MOST kids use a spoon."

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* Have him blow bubbles, blow on a kazoo, blow feathers into the air, anything that helps him get air out.
* We bought a large cosmetic mirror and let him look at himself while he tried to make sounds. It really helped later on.
* I was always one to talk non-stop to my kids. These guys need you to ask questions non-stop. My little guy still can't ask why or where questions, so we model them. "Why did that leaf fall down?" "Oh, because the wind blew."
* Between the "one say one word at a time" and when he started talking fairly well, I missed a step. There was a time where I'm pretty sure he could have understood me, but I didn't know it.
* My guy can't rhyme at all. I was told to read Dr. Seuss and more Dr. Seuss and any book with rhythm.
* Music classes have been shown to help the brain make connections. If you have a kindermusik nearby, I'd give it a shot. If not, there are some CDs that are slow enough they have a chance to comprehend (not We Sing!!). I think Discovery Toys had one that was especially good.
* In addition to auditory processing disorder, research apraxia. There are tons of fantastic ideas for helping kids.
Good luck! DS4 is still testing almost a year behind, but we are so thrilled with how well he is doing. So we start him in school a year later. Who cares?