One of the most subtle and difficult things to write is dialogue. All too often it sounds stilted and forced. Perhaps worse, all the characters sound the same.
I found a discussion on Reddit where the style of a character’s speech might be quantified.
At heart, the idea is to list a series of speech factors and assign each character a rating of 1,2, or 3 per factor.
For example, on the list given below, a rating of 2,1,3,3,2,1 would indicate a character who speaks in a terse, insecure, submissive, hijacking fashion. (Ratings of 2 are balanced, meaning no preference, with 1 and 3 being left and right options respectively.) And yeah, go figure what sort of character humbly and tersely hijacks conversations!
Obviously this system could be extended, with more stylistic pairs, and the ensuing Reddit discussion provides a few more examples. The numeric range might be extended with (say) 5 as a middle value, 1 through 4 as degrees of leftness, and 6 through 9 as degrees of rightness on the given pair, so it’s more of a scale, rather than a binary choice.
I’d add in some character-specific quirks, such as accent or jargon, which don’t fit neatly into a bipolar range.
And a character who is normally languid in delivery might become more excitable or terse in a crisis.
The discussion is well worth reading, and if nothing else provides a handy way of keeping track of how characters speak, especially if there are several in a scene.