I'm sure it's partially from the old equipment and the recording tapes aging, degrading quality and giving them a tinny and accelerated sound, but how much of this is driven by the culture of radio at the time, such as inflection, pacing/cadence, etc? When did this begin to change and how?
hi! there's always room for more input, particularly regarding early sound equipment, but regarding speech patterns, check out this section in the FAQ* for related threads:
*see the link on the sidebar or the wiki tab