I know that all toddlers are a bit like this, but my DS is particularly bad (a/c his nursery, not just me!). He can hear - if I'm whispering or calling from the other room he hears me just fine as long as it's something he wants to hear.
He just doesn't listen at all. Not when I'm calling him to come back away from the busy road, not when I'm telling him not to climb on the table as he'll hurt himself (he did), not when I'm telling him to wait and let me go first on the icy fire escape (he pushed past and fell down a flight of stairs).
Even when I get down to his eye level and try to get eye contact to tell him something important, he looks over my shoulder and talks over the top of me. This is the main reason he doesn't listen - because he just never stops talking and of course he can't listen and talk at the same time. And as far as he's concerned nothing I could be saying could ever be as fascinating as his continual discourse on the subject of trains, diggers, teddy bears, poo... etc. etc. How can I get him to listen? Pleeeeeease? Any tips very gratefully received.