It is well-known (amongst certain cultural historians and phoneticists at least)
that the modern pronunciations of French, Danish and English (at least)
were the result of speech impediments or mannerisms at royal courts, and, in the case of English, also of the importation of Dutch- and then German-speaking rulers and their courtiers and soldiers.
In modern times the speech of female, white Americans has altered very noticeably. As women more and more assert their rights and grievances, their speech has become more nasal, more penetrating, faster, and (inevitably) less clear. It sounds like souped-up Barbie-speak, and may yet evolve into Chipmunk.
Hillary Clinton is a comparatively mild example, but I find that more than half a minute of her shrieky delivery makes me turn off the radio to avoid a headache.