According to this column, Cecil Adams was on the radio:
http://www.straightdope.com/classics/a4_134.html
Does a recording survive of Mr. Adam’s voice? Anyone recall hearing this program? Did he show up at the radio station?
As Cecil is a fiction, probably not. I do vaguely remember a radio interview I heard about the straight dope, I think it was done by the illustrator, Slug Signorino (a made up name if ever there was one), or maybe it was Ed Zotti.
I would like to see an update on this Scientology column. I agree with everything that is said, but we have learned a lot more information about this cult and its craziness since this article.
Ed Zotti is a semi-frequent guest on Milt Rosenberg’s radio show in Chicago.
Here is an archived clip from March 24, 2006. It is a nearly 5 minute clip and Milt does nearly as much talking as Ed does (a regular occurance on the show.)
I don’t think you’ll get any closer to a recording of Cecil. 
Here’s another thread concerning Ed on the radio.
In Post #7 of that thread, Tuba mentions a podcast of the show.