Nobleman Japanese

I just finished watching "The Hidden Fortress" (great film) and a minor plot point has the Princess pretending to be mute so that the peasants accompanying them don't pick up on her lineage based on her manner of speak.
My Japanese is still not at the level where I understand everything, let alone pick up on such subtleties, so I was wondering if anyone knew and had specific examples of how Japanese language spoken by noblemen in ancient Japan differed from "regular" Japanese (I'd speculate maybe an extra keigo? Specific particles and pronouns? What else?) and whether any of it carried over to modern Japanese, in one form or another.

In the 70's while stationed in Fukuoka , I learned my Japanese from young hippy like school dropouts at the bar where I worked. When I went to Tokyo for a week , almost every Japanese person I talked to commented how horrible my Japanese was and did an ignorant fisherman teach me , LOL. Latter when I returned to Maine and took a formal class on Japanese , my teacher said my Japanese was gutter Japanese and to forget all of it.

I'm no historian, so I have no idea how accurate my impression is, but I do love a good period drama or film. At least as dramatized, nobles speak clearly, and generally with tons of keigo, and very few if any dropped particles. They also adjust their keigo closely to the situation with close attention to whether to speak humbly or... well... not so humbly.

Conversely, commoners slur words, make vowel substitutions, drop particles, speak plain form to each other. When interacting with nobles they try, badly, to use humble language.

Additionally, the vocabulary choices are enormously different, especially pronouns and verbs. A commoner would never call someone 汝 or themselves 吾輩. Only servants and low-mid ranked nobles say 承りました... commoners simply don't use the word, they'll just throw honorific attachments onto 分かる (e.g. 分かっておりました) and the highest ranks don't need to show deference.

I would think the hardest part of passing as a different class than your actual one would be more one of manner of speech than vocabulary though. The difference in accent is nearly as stark as the difference between cockney and the royal court. At least for serious period pieces. Lighter anime and dramas the language gets much closer together and becomes just a few pronoun and verb choices. As for the real history, well, hard to say, but I tend to think the more serious dramas are likely closer to the truth.

Certainly not *accurate*, of course. Just like a medieval film in the west doesn't use truly accurate Middle English, for the sake of modern audiences, period works in Japan also make adjustments to be comprehensible to modern audiences while trying to retain the period 'feel' of the language.

All you have to do is recall (or look up on youtube) the Showa Emperor's radio speech announcing the end of the war. The language is very formal, and the intonation is different from how common people intone their speech. The language was so unusual, the broadcast required newscasters to explain it in normal speech. If you want to see a comparison of the text, you can see one here

As Chris-san suggested, they were actually speaking in modern Japanese (pseudo classical Japanese) in the film.