Come once more?

Why do people feel it acceptable to whisper so softly when they need to be heard. The sharing of time-sensitive information does not call for a whisper.
Also... people who assume that they can center my every moment around them. There is never a calling for that. How on earth does that make sense.
I recently had an argument with someone, and I really don't think that anybody was right. Really we were both wrong... but, in different ways.
He was wrong for assuming that i could drop everything. And wrong for assuming that my completion of one task means that my entire night was free.
I was wrong for snapping at him when he called all excited about dinner. And then again when he wanted me to come for dinner.
Now, I have made sure to make him sound like the better person in this, because he really is a pretty good guy... but seriously-- I need time to myself sometimes... even if I don't give him prior notice of the subject.