I have problems discerning certain tone of voice. I'm also not good at noticing my own tone of voice, or my volume. Everybody who knows me is forever telling me I have no concept of whispering, because when I "whisper" I just lower the tone of my voice apparently but stay at the same volume. To me it sounds like I'm whispering, I can barely hear myself.

I think it's pretty common for those of us on the spectrum to not be able to discern tone of voice, though it is called a spectrum for a reason. Not everybody has the exact same level of problems. For instance, I still understand sarcasm pretty well and in fact I'm a rather sarcastic person myself. But if somebody was to say something with a 'hidden' undertone, it would go right over my head.