What caused broadcasts to have that “vintage” sound in the mid 20th century

Question

Not talking about the static, mainly the voices of people.

Examples:

https://youtu.be/yYAw79386WI?si=SKCkEeHFLn83ixCB (skip to 4:30)

And a final example of a modern recreation

In: Technology

Answer 1

Many people in the media spoke with the Transatlantic accent. The accent was embraced especially by members of the Northeastern upper class, as well as in schools for film, radio, and stage acting, with its overall use sharply declining after the Second World War. The Mid-Atlantic accent is not a native or regional accent; rather, according to voice and drama professor Dudley Knight, “its earliest advocates bragged that its chief quality was that no Americans actually spoke it unless educated to do so”.