Nothing is secret in Hell. The place basically takes the worst parts of you, exaggerates those qualities until they consume your whole existence, and then puts you up for display. If you live in circle six, everyone knows you’re a heretic. Circle 8.2? A flatterer. The center of Hell? Oh, you devil. It’s pretty straightforward.
In case you missed the giant road signs saying "Gluttons, 3 miles," you can figure out what kind of person someone is by his behavior. Because there’s no such thing as free will in Hell. If you’re wearing a flashy gold robe, you’re a hypocrite. Boiling in blood? A murderer. Swimming in tar? A barrator. You get the point.
Well, you kind of have to know Italian to get this kind of characterization. Sometimes a guy’s name will give away clues to his character. (The cool thing is that most of these "characters" were real-life people. We know. Historians have checked. So Dante isn’t making this up.) Ciacco. Remember him? In Italian, his name means "hog" and he's a glutton.
Bocca degli Abati in the ninth circle, first ring gets mad at Dante, refusing to name himself and telling Dante to get lost. "Bocca" in Italian means "mouth." You could interpret it as bad-mouthing.
Then you’ve got the demons. When you’re in a group called Malebranche or "Evil-Claws," you’re bound to be evil. Though maybe not all of them have claws, they do all have grappling hooks with which to stab the sinners.
Moving on to Pier della Vigna, "Pier" comes from the Latin word for "stone" and "vigna" in Italian means "vine." Well, as a suicide, Pier is immobilized like stone in the shape of a tree.
Brunetto comes from "bruno" meaning "brown" and the suffix "-etto" gives the word a bad or naughty connotation. Because Bruno is a sodomite, he’s punished by raining flames, which burn him and turn him brown.
Finally, you’ve got Dante himself. Bet you didn’t know that "Dante" is a shortened form of the name "Durante" which means "enduring." He went through Hell. We consider that pretty enduring.
Our ghostly guide harkens from the golden age of Rome, was their most celebrated poet of his day, and fills the role of mentor for aspiring-poet Dante. How do you think he speaks? Exactly. His speech is lofty in tone, highfalutin’ in style, what with all his "O unenlightened ones" and other exclamations. Virgil is deeply eloquent to the handful of people that can understand him. This idea of the "decorated word," the literal translation for "parole ornate" conveys all of these meanings, plus one other important aspect we haven’t mentioned yet.
Remember how Virgil always answers Dante’s questions by not answering them? He always starts his responses at some random tangent and works his way towards an answer. The point is, Virgil has tact. It’s with these types of long-winded and elaborate gestures that Virgil can butter people up, impress them with his words, and only then get to the meaty content of the conversation. This is why he always gets what he wants, whether it’s passage across some Underworld river, a confession from a sinner, a protector from a violent gang of half-breeds, or a free ride from a monster.
But sometimes Virgil's persuasion doesn’t work as well as he’s like it to. Like at the gates of Dis. Here, we get to the downsides of his linguistic style. With all his half-hour orations and heavy-handed metaphors, Virgil can get a little tiring to listen to if you’re in a hurry, and all his five syllable words can make him come off as a little cocky. If you’re a straight-talker, you might suspect Virgil of trying to sneak one past you or to subtly insult you. His fancy way of speaking might come off as pretentious or dishonest to you. So Virgil’s style can rub some people the wrong way.
Everyone seems to recognize Dante by his Tuscan (or Florentine) accent. Unfortunately, the English translation doesn’t convey a sense of what Dante’s accent sounds like, though the Italian is written in a Florentine dialect. Another reason that Dante sounds normal to us is that he’s dictating the story, and he doesn’t sound weird to himself.
But Dante does make a point here: one’s identity is formed partially by his language. Virgil speaks all highfalutin’ so we know he’s a poet. Francesca speaks in the manner of courtly love, so we know she’s a princess. Ulysses speaks Greek. Guess where he’s from? Ditto for Dante. Everyone can tell where he comes from just by hearing his voice. Though being a Florentine is not something Dante’s proud of, he simply cannot hide it.
Ah! Oh! Ooh! Oww! Grrrrrr! That’s how the sinners sound. At least when Dante isn’t pumping them for information. In fact, this is some gross underestimation of what Dante hears when first entering Hell. If you haven’t noticed, the sinners’ vocalizations don’t actually say anything; there are no words. But that’s the whole point. Because they’ve all either neglected or abused the "good of the intellect," they can’t really use language effectively anymore. They’ve forfeited that right. And so they’re relegated to bestial cries, howls, grunts, and such.