>>37303734Being able to influence people, especially by unconscious means, is what I think is too close to mind control, but I digress, in that case, mass speaking machines like an early megaphone is what seems to be closest to your idea, maybe this megaphone could be a telepathic megaphone or whatever, I dunno.
Soundposts could also be a representation of plays and of poetry that could be passed around, it doesn't necessarily have to be magical, but if you do want it to be magic, I don't see why specific instructions of a particular soundpost could also not be passed around in paper, the printing press should be relatively common around the world anyways. It's one of the few things I could see being universal in the planet across all generals.
The newtypes could do it with smaller machines I guess, or just outright without them.