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

Limited frequency bandwidth. Basically, a large part of the audible range is cut off, either so the audio can be transmitted more easily, or because of the imperfect analog storage medium that has degraded over time and lost a large part of that range.

ELI5: milk spoils after a while, or gets filtered to lose some of its nutrients.