I'm aware of the well-recognized Trans Atlantic accent used in films until approx. WWII, but I cannot find any information on why actresses in more recent, but not contemporary movies have such a standard, singsong tone. It's so pervasive that, to me, I can hear this type of voice and automatically know the movie is at least twenty years old. Was it simply how women used to speak, similar to the "vocal fry" trend from the past several years? What is this accent? Is it still Trans Atlantic?

Ive linked some scenes that exemplify the type of voice

The Hand that Rocks the Cradle (1992)

[The Shining (1980)] (https://youtu.be/LtI0uG6tjew)