Do we have video casts too? If so, "audio feed" would seem weird for that.
Personally I listen to a bunch of podcasts (and blogs, too), and I've heard and always called them an "RSS feed" or just a "feed". Or "podcast" or of course vendor names (ok, really only iTunes).
Checking Google, I get:
12k "atom feed"
392k "audio feed"
430k "web feed"
575k "rss feed"
752k "podcast feed"
Take those with a grain of salt, of course, especially since Google often includes related terms, even when quoted now.