Did you know that before television, people got most of their in-home, broadcast entertainment from radio? These days, about the only thing we listen to on the radio is music and news (with a healthy helping of public radio shows that may offer somewhat more). But back in prehistoric times, you could listen to "shows" on the radio: soap operas, comedies, dramas, and whatever else you could imagine.
Here’s a link to a whole bunch of shows that were broadcast as recently as the late 1970s/early 1980s: Mind Webs was a "…series out of WHA Radio in Wisconsin" that "featured weekly readings of science fiction stories". It’s not radio drama, quite, but they are professional readings done with embellishments like background music, sound effects, and more, to enhance the listening experience.
In fact, the Internet Archive is a great place to go to find all sorts of content that’s interesting;
The Internet Archive is building a digital library of Internet sites and other cultural artifacts in digital form. Like a paper library, we provide free access to researchers, historians, scholars, and the general public.
They’ve got hundreds of thousands of different audio, video and text files you can download and enjoy. Some are released under "open source" or Creative Commons licenses that encourage sharing, others are in the public domain and thus free to all. You can watch old movies, listen to scratchy old recordings, or hear the latest in fiction, public affairs, or electronica.