I haven’t had the chance to research this, but Obama used to be a regular guest and host on WOVN Radio in Chicago. I would love to find some of his archives.
WVON - The Talk of Chicago - provides an interactive forum for the African- American community to discuss current, social, economic, and political issues.
wvon.com/
Obama also used to do commentaries for NPR, back in the 1990s - I’d like to hear them, as well.