(What does this face say to you?)Each of us hears things differently. Where I might think you're angry with the tone of voice you use, another person might simply think you're under stress. Body language helps us figure it out, but even that's subject to interpretation. However, it's still far easier to garner meaning when we can listen to someone than when we just read their words.
How many internet arguments have begun over a misinterpretation? A while back, I sent out an email with a picture of a scantily clad woman in a bikini washing a car with her tits. And yes, I used the word tits in the email. A female friend of mine came back with a stark one line reply that simply read, "Mine are called breasts." I thought I'd offended her and apologized profusely for being a Neanderthal. It turns out she was quite surprised by the backtracking on my part since she thought she was adding a funny retort.
So how do we solve the problem? We've heard countless times that we should show rather than tell, so coming right out and saying "this guy is diabolical" is frowned on. We're supposed to show it through his actions, but how does one do that during dialogue? Sure, the dialogue itself could do it, but don't even the most evil creatures sometimes just engage in conversation? You may want something to evoke a feeling in the reader that the character speaking is god-like, but how do you do that through dialogue alone, especially if the person is making their first statement?
(I told you to blow the fucking whistle!)The way I sometimes communicate tone of voice is through the use of different fonts. Yes, it's trite, and it can also make me sound like a douche, but there are times it adds to the story. In Salvation Day, there is a scene where the main character confronts his first angel. The angel is yelling that there's no way the guy could possibly pull off his objective, which is to kill God. The angel simply saying "You will never succeed!" didn't seem to bring out the tone of power I wanted to convey, so I decided to use Gaudy Stout. The bold tone had just the right feel to give an "oh shit" factor.
Of course, this isn't a technique that you can use often, but done sparingly, I think it helps the reader get into the emotion of what's being said(despite a few "established" writers telling me they didn't approve). Giving characters distinct tones of voice in critical situations can bring tension to a story, and it can suck the reader in even further.
You have to be willing to experiment where it makes sense if you want to stand out and draw in readers. It doesn't work every time, but when it does, it makes the story that much more real.