In addition to the "expressiveness" difficulties with communication, zombies and traditionally biotic folks have the hurdle of our slower rate of speech to contend with. Most...of...us...speak...very...slowly. Please note, however, that most of us hear just fine, so shouting at the top of your lungs isn't going to speed the conversation up any faster than it would with, say, someone who only speaks Norwegian. Conversely, volume is a problem for us as well; many zombies can make their voices raise above a whisper only with great effort.
I'm afraid that our inability to speak at a normal speed causes many of us to not speak at all, unfortunately. To be dead in public is almost the very definition of being self-conscious, where the dead person is well aware that all the eyes of the living are upon them. Add to that the idea of speaking in public when you can't quite get the words out fast enough and you have many kids that would rather say nothing at all.
This doesn't mean we don't have anything to say.
The fact that typical communication happens at a much faster rate, perhaps, then ever before in human history only compounds the matter. ZOMG! Lol, srsly. We understand that it is difficult to go from speed-of-thought texting and near-telepathic communications with living friends to the slow, drawn out dialogue you may have with a zombie, trust me. It wasn't all that long ago when we were doing the same things as you were.
I have a friend, a zombie, named Melissa who lost the ability to speak in a fire. For the record, the fire that injured her in this way was not what killed her; she was hurt in a fire that was meant to destroy her and a group of zombies she lived with. A fire that was mostly successful--only she and a boy escaped a blaze that left many others reterminated.
Melissa communicates now with a whiteboard and marker. She can't write very fast, or very neatly, and it sometimes takes her longer to write what she wants to say than it does even the slowest zombie to speak. Communicating with Melissa, then, is an act of patience even for a zombie. But, like most acts of patience, it is always well worth the effort. Despite all of the pain and heartache she has gone through (or maybe because of it), the things that she writes are inevitably profound. I've talked to her a few times since she began taking classes at the Hunter Foundation, and she has often provided me the necessary insight to solve an issue that I or one of our zombie friends is dealing with.
I guess what I'm saying is, just like in my post regarding expression, patience is the key. I've come to the realization that, between two people, the listener has the primary responsibility in communication. The best, most erudite speaker in the world is going to have a hard time getting through to someone who isn't paying any attention, whereas a good listener--one who is patient, open, and making an honest effort to understand--can often hear even the things that the shy, still voice